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Engine Controls - Trouble Shooting - No Codes - 4.8l, 5.3l & 6.0l Cadillac Escalade GMT800

Testing & Diagnostics ~8407 words

MODEL IDENTIFICATION

Vehicle model is identified by the fifth character of Vehicle Identification Number (VIN). The VIN is stamped on metal pad on top of left end of instrument panel, near windshield. See MODEL IDENTIFICATION table.

Series (1)Model
"C"2WD Avalanche, Escalade, Sierra, Silverado, Suburban, Tahoe, Yukon & Yukon XL
"G"RWD Chevy Express & Savana
"H"AWD Chevy Express & Savana
"K"AWD/4WD Avalanche, Escalade, Escalade ESV, Escalade EXT, Sierra, Silverado, Suburban, Tahoe, Yukon & Yukon XL
"N"Hummer H2
"S"Envoy XL & TrailBlazer EXT (2WD)
"T"Envoy XL & TrailBlazer EXT (AWD/4WD)
(1) Vehicle series is fifth character of VIN.
(1)Vehicle series is fifth character of VIN.

MODEL IDENTIFICATION

INTRODUCTION

Note. Unless indicated otherwise, Sierra and Silverado includes Cab & Chassis Sierra and Cab & Chassis Silverado. Savana includes Savana Special and Savana Camper Special.

Before diagnosing symptoms or intermittent faults, follow proper workflow. See DIAGNOSTIC STARTING POINT - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or DIAGNOSTIC STARTING POINT - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, proceed to NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article. If no DTCs are present and a driveability condition exists, diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

Note. Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or computer control unit. Check with manufacturer for latest chip or computer application.

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing.

Note. For specific testing procedures, see SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article. For specifications, see ON-VEHICLE ADJUSTMENTS - TRUCKS - EXCEPT TRACKER or appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

PRELIMINARY INSPECTION

  1. Verify on-board diagnostics are working by performing «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-158498-S01208107442003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  2. Ensure PCM and MIL functions properly.
  3. Ensure no DTCs (except intermittent) are stored.
  4. Perform fuel system pressure test. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  5. Visually inspect all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. See SYMPTOMS .

SYMPTOMS

Note. Before proceeding with any symptom diagnosis, perform PRELIMINARY INSPECTION .

Note. If PCM displays data but engine fails to start, see NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.

SYMPTOM DIAGNOSIS

Symptom checks should not be used unless symptom occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE articles were performed before diagnosing a symptom. Symptoms available for diagnosis include

  1. «DETONATION/SPARK KNOCK»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  2. «ENGINE BACKFIRES»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  3. «ENGINE CUTS OUT, MISSES»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  4. «ENGINE DIESELING/RUN-ON»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  5. «HARD START»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  6. «HESITATION, SAG OR STUMBLE»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  7. «LACK OF POWER OR SLUGGISH»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  8. «POOR FUEL ECONOMY»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  9. «POOR FUEL FILL QUALITY»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  10. «ROUGH, UNSTABLE OR INCORRECT IDLE & STALLING»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)
  11. «VEHICLE SURGES OR CHUGGLES»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l)

Symptom Definition

A mild to severe ping, usually worse during acceleration. Engine makes sharp metallic knocks which change with degree of acceleration.

Possible Causes & Corrections

Check the following items

  1. Search for bulletins.
  2. Verify that the PCM grounds are clean, tight, and in the proper locations.
  3. If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicles minimum octane requirements. Road test the vehicle and re-evaluate the vehicles performance.
  4. Check fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  5. Inspect for a restricted fuel filter.
  6. Inspect for a contaminated fuel condition.
  7. Inspect for conditions that can cause engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination, or vacuum hoses that are split, kinked, or improperly connected.
  8. Verify that spark plugs are of proper heat range.
  9. Low engine coolant.
  10. Restricted air flow to radiator or restricted coolant flow through the radiator.
  11. Inoperative cooling fan
  12. Excessive oil in combustion chamber, may be caused by leaking valve seals.
  13. Low cylinder compression. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  14. Combustion chambers for excessive carbon build-up. Clean combustion chamber by using top engine cleaner.
  15. Inspect for incorrect basic engine parts. Such as, camshaft, cylinder heads, pistons, etc.
  16. Inspect the Park/Neutral Position (PNP) switch operation.
  17. Inspect transmission Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. A TCC applying too soon can cause the engine to spark knock.

Fuel ignites within intake manifold or in exhaust system, making a loud popping noise.

Check the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Inspect for incorrect fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  4. Inspect for a restricted fuel filter.
  5. Inspect fuel injectors. See «FUEL SYSTEMS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline) in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  6. Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
  7. Inspect air intake system and crankcase for air leaks.
  8. Inspect for an inaccurate speedometer.
  9. Use a scan tool in order to monitor the Knock Sensor (KS) system for excessive spark retard activity. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  10. Inspect for proper ignition voltage output using Spark Tester (J-26792).
  11. Remove spark plugs and inspect for wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  12. An improper spark plug gap will cause a driveability problem.
  13. Determine the cause of the fouling before replacing spark plugs.
  14. Visually and physically inspect secondary ignition for ignition wires arcing to ground or ignition coils arcing to ground.
  15. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.
  16. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  17. Inspect for loose ignition coil grounds. See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  18. Inspect engine for low coolant level.
  19. Inspect engine thermostat for proper operation and for correct heat range.
  20. Inspect engine mechanical for compression, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs, excessive oil in combustion chamber or leaking valve seals. See «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  21. For incorrect basic engine parts. Inspect camshaft, cylinder heads, pistons, etc.
  22. Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the underhood Vehicle Emission Control Information label.
  23. Inspect intake manifold and exhaust manifold passages for casting flash.
  24. Inspect the transmission Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. The scan tool should indicate an RPM drop when TCC is commanded ON.
  25. Inspect exhaust system for possible restrictions. Inspect exhaust system for damaged or collapsed pipes. Inspect the mufflers for heat distress or possible internal failure. Inspect for possible plugged catalytic converters.
  26. Electromagnetic Interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring engine RPM. A sudden increase in RPM with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near ignition control circuits.
  27. Inspect Park/Neutral Position (PNP) switch operation.
  28. Inspect for faulty motor mounts.
  29. Inspect intake and exhaust manifold passages for casting flash.

Cuts out, misses is defined as a steady pulsation or jerking following engine speed, usually more pronounced as engine load increases. Exhaust may have a steady spitting sound at idle or low speed. Perform VISUAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.

Check the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Remove air filter element and inspect for dirt and for restrictions.
  4. Inspect fuel injectors. See «FUEL SYSTEMS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline) in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  5. Inspect for incorrect fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  6. Inspect for a restricted fuel filter.
  7. Inspect for a contaminated fuel condition.
  8. Inspect for conditions that may cause engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate MAF sensor, blockage MAF sensor inlet screen, vacuum hoses that are split, kinked, or improperly connected, air intake duct that is collapsed or restricted, or air filter that is dirty or restricted.
  9. Inspect for conditions that may cause engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination or vacuum hoses that are split, kinked, or improperly connected.
  10. Monitor Knock Sensor (KS) system for excessive spark retard activity. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  11. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.
  12. Test for proper ignition voltage output with a Spark Tester (J-26792).
  13. Remove spark plugs and inspect for correct heat range, wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  14. An improper spark plug gap will cause a driveability problem.
  15. Determine cause of the fouling before replacing spark plugs.
  16. Visually and physically inspect the secondary ignition for ignition wires arcing to ground, ignition wires for proper engagement to spark plug or ignition coils for cracks or carbon tracking.
  17. Using scan tool, monitor the Misfire Current Counters while driving vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  18. Inspect engine mechanical for compression, sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excessive oil in combustion chamber, caused by leaking valve seals. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  19. For incorrect basic engine parts. Inspect camshaft, cylinder heads, pistons, etc.
  20. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in a no-start, a start and stall, or an erratic performance.
  21. Inspect exhaust system for possible restrictions. Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. Inspect for possible plugged catalytic converters.
  22. Electromagnetic Interference (EMI) on the reference circuit can cause an engine misfire condition. A sudden increase in indicated RPM with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control circuits if a condition exists.
  23. Inspect intake and exhaust manifold passages for casting flash.

Engine continues to run (but very rough) after ignition is turned off. If engine runs smoothly, check ignition switch.

Check for the following

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Inspect fuel injectors for leakage or diagnose fuel system. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.

Engine cranks okay, but does not start immediately. Engine eventually starts and may run okay or soon stall.

Check the following items

  1. Verify that PCM grounds are clean, tight, and in the proper locations.
  2. Search for bulletins.
  3. Monitor Engine Coolant Temperature (ECT) sensor with scan tool. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article. Compare engine coolant temperature with the ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, check for high resistance in the coolant sensor circuit.
  4. Inspect the Mass Airflow (MAF) sensor installation. A MAF sensor that is incorrectly installed may cause a hard start. The embossed arrows on the MAF sensor indicate the direction of the intake air flow. The arrows must point toward the engine. Install MAF sensor in the proper direction.
  5. Inspect Camshaft Position (CMP) sensor for proper mounting and/or a bad connection. An extended crank occurs if PCM does not receive a CMP signal.
  6. Check fuel pump relay operation. See «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  7. A faulty in-tank fuel pump check valve allows fuel in the lines to drain back to the tank after the engine stops. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  8. Verify that both fuel injector fuses are not open. An open fuel injector fuse causes four injectors and four ignition coils not to operate. Inspect the injector circuits and the ignition coil circuits for an intermittent short to ground. Replace the fuse.
  9. Check fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  10. Inspect for a restricted fuel filter.
  11. Inspect for a contaminated fuel condition.
  12. Verify that both fuel injector fuses are not open. An open fuel injector fuse causes four ignition coils and four fuel injectors not to operate. Inspect the ignition coil circuits and the fuel injector circuits for an intermittent short to ground.
  13. Inspect for proper ignition voltage output with a Spark Tester (J-26792).
  14. Remove spark plugs and inspect for correct heat range, wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  15. Determine cause of the conditions before replacing spark plugs.
  16. Inspect for bare or shorted ignition wires.
  17. Inspect for loose ignition coil grounds. See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  18. Excessive oil in combustion chamber or leaking valve seals.
  19. Low cylinder compression. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  20. Combustion chambers for excessive carbon build-up. Clean chambers using top engine cleaner.
  21. Incorrect basic engine parts. Inspect cylinder heads, camshafts, pistons, etc.
  22. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with CKP sensor. This could result in a no-start, a start and stall, or an erratic performance.

Momentary lack of response when accelerator is pushed down. May occur at any vehicle speed. Usually occurs after a stop. If severe enough, may cause engine to stall.

Check for the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Inspect Manifold Absolute Pressure (MAP) sensor operation. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  4. Check fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K" & "N" SERIES - FLEX FUEL & GASOLINE article.
  5. Inspect for a restricted fuel filter.
  6. Inspect for a contaminated fuel condition.
  7. Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 ignition coils and 4 fuel injectors not to operate. Inspect ignition coil circuits and fuel injector circuits for an intermittent short to ground.
  8. Inspect cause for engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate MAF sensor, blockage on MAF sensor inlet screen, vacuum hoses that are split, kinked, or improperly connected, air intake duct that is collapsed or restricted, or an air filter that is dirty or restricted.
  9. Inspect cause for engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination, or vacuum hoses that are split, kinked, or improperly connected.
  10. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.
  11. Test for proper ignition voltage output with Spark Tester (J-26792).
  12. Remove spark plugs and check for correct heat range, wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  13. An improper spark plug gap will cause a driveability problem. Gap spark plugs using a wire gauge gap tool.
  14. Determine cause of the fouling before replacing spark plugs.
  15. Using scan tool, monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  16. Inspect for loose ignition coil grounds.
  17. Inspect engine thermostat for proper operation and for proper heat range.
  18. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in a no-start, a start and stall, or an erratic performance.
  19. Inspect generator output voltage. Repair charging system if generator output voltage is less than 9 volts or more than 16 volts.

Engine delivers less power than expected. Little or no increase in speed when accelerator is applied.

Check the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Remove air filter element and inspect for dirt or for restrictions.
  4. Inspect both injector fuses for being open. An open injector fuse causes 4 ignition coils and 4 injectors not to operate. Replace fuse. Inspect the ignition coil circuits and injector circuits for an intermittent short to ground.
  5. Inspect for incorrect fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  6. Inspect for a restricted fuel filter, contaminated fuel, or improper fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  7. Inspect for a contaminated fuel condition.
  8. Inspect cause for engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate MAF sensor, blockage on MAF sensor inlet screen, vacuum hoses that are split, kinked or improperly connected, air intake duct that is collapsed or restricted, or air filter that is dirty or restricted.
  9. Inspect cause for engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination, or vacuum hoses that are split, kinked or improperly connected.
  10. Use a scan tool in order to monitor the Knock Sensor (KS) system for excessive spark retard activity. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  11. Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 ignition coils and 4 fuel injectors not to operate. Inspect ignition coil circuit and injector circuits for an intermittent short to ground.
  12. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied.
  13. Inspect for proper ignition voltage output with Spark Tester (J-26792).
  14. Remove spark plugs and inspect for correct heat range, wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  15. An improper spark plug gap will cause a driveability problem. Gap spark plugs using a wire gauge gap tool.
  16. Determine the cause of fouling before replacing spark plugs.
  17. Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. If a misfiring cylinder can be located with a misfire, use DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  18. Inspect for loose ignition coil grounds.
  19. Verify that the engine coolant temperature is not greater than 266°F (130°C). This condition causes the PCM to operate in Engine Coolant Over Temperature - Fuel Disabled Mode. While in Engine Coolant Over Temperature - Fuel Disabled Mode, the PCM will disable the fuel injectors to 4 cylinders at a time to keep engine temperatures from reaching damaging levels. The driver may perceive the Engine Coolant Over Temperature - Fuel Disabled Mode as a lack of power, miss or rough idle. If vehicle operates in this condition, diagnose engine overheating.
  20. Inspect for excessive oil in the combustion chambers. May be caused by leaking valve seals.
  21. Test for low cylinder compression. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  22. Inspect for incorrect basic engine parts. Inspect camshaft, cylinder heads, pistons, etc.
  23. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in a no-start, a start and stall, or erratic performance.
  24. Inspect exhaust system for possible restrictions. Inspect exhaust system for damaged or collapsed pipes. Inspect the mufflers for heat distress or internal failure. Inspect for plugged catalytic converters.
  25. Inspect transmission Torque Converter Clutch (TCC) for proper operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

Fuel economy, as measured by an actual road test, is noticeably lower than expected. Current fuel economy is noticeably lower than previous fuel economy.

Check the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Inspect the owner's driving habits. Is the A/C ON or the defroster mode ON full time? Are the tires at the correct pressure? Are the wheels and tires the correct size? Are there excessively heavy loads being carried? Is the acceleration rate too much, too often? Remove air filter element and inspect for dirt or for restrictions. Replace as necessary.
  4. Inspect the type, quality and alcohol content of fuel. Oxygenated fuels have lower energy and may deliver reduced fuel economy.
  5. Inspect fuel injectors. See «FUEL SYSTEMS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline) in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  6. Inspect for incorrect fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  7. Inspect for a restricted fuel filter. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  8. Inspect for a contaminated fuel condition.
  9. Ensure that each fuel injector harness is connected to the correct injector and cylinder. Relocate the injector harnesses as necessary.
  10. Inspect for foreign material accumulation in the throttle bore, coking on the throttle valve, or on the throttle shaft.
  11. Inspect cause for engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate MAF sensor, blockage on MAF sensor inlet screen, vacuum hoses that are split, kinked or improperly connected, air intake duct that is collapsed or restricted, or air filter that is dirty or restricted.
  12. Inspect air intake system and crankcase for air leaks.
  13. Inspect crankcase ventilation valve for proper operation. See «POSITIVE CRANKCASE VENTILATION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  14. Inspect for an inaccurate speedometer.
  15. Use scan tool in order to monitor the Knock Sensor (KS) system for excessive spark retard activity. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  16. Inspect for proper ignition voltage output with Spark Tester (J-26792).
  17. Remove spark plugs and inspect for wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  18. An improper spark plug gap will cause a driveability problem.
  19. Determine the cause of fouling before replacing spark plugs.
  20. Visually and physically inspect the secondary ignition for ignition wires arcing to ground or ignition wires for proper routing.
  21. Soaking the secondary ignition system with water from a spray bottle may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.
  22. Inspect for loose ignition coil grounds. See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  23. Inspect for low engine coolant level.
  24. Inspect engine thermostat for proper operation and for correct heat range.
  25. Inspect engine mechanical for compression, sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excessive oil in combustion chamber, caused by leaking valve seals. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  26. Inspect for incorrect basic engine parts. Inspect camshaft, cylinder heads, pistons, etc.
  27. Visually and physically check the vacuum hoses for splits, kinks, and proper connections and routing as shown on the underhood Vehicle Emission Control Information label.
  28. Inspect transmission Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. The scan tool should indicate a RPM drop, when the system commands the TCC ON.
  29. Inspect exhaust system for a possible restriction. Inspect exhaust system for damaged or collapsed pipes. Inspect the mufflers for heat distress or possible internal failure. Inspect for possible plugged catalytic converters.
  30. Electromagnetic Interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control circuits, if a condition exists.
  31. Inspect the Park/Neutral Position (PNP) switch circuit.
  32. Inspect intake and exhaust manifold passages for casting flash.
  33. Inspect brake system for dragging or improper operation.

Difficult to fill.

Check the following items

  1. Check valve is stuck closed.
  2. Fill limiter vent valve is stuck closed.
  3. Evaporative Emission (EVAP) canister is restricted.
  4. EVAP canister vent solenoid is stuck closed.
  5. Restricted EVAP pipes.
  6. High Reid Vapor Pressure (RVP).
  7. High fuel temperature.
  8. The fuel filler hose/pipe is pinched, kinked or blocked.
  9. The fuel feed hose or crossover hose is pinched, kinked or blocked.
  10. The ignition switch is on.

Overfill.

Check the following items

  1. Pressure relief valve in fill limiter vent valve is stuck open.
  2. Pressure relief valve in fill limiter vent is valve leaking.
  3. Fill limiter vent valve is stuck open.
  4. Fill limiter vent valve is leaking.

Premature shut-off of the fuel dispensing nozzle.

Check the following items

  1. Check valve is stuck closed.
  2. Fill limiter vent valve is stuck closed.
  3. EVAP canister is restricted.
  4. EVAP canister vent solenoid is stuck closed.
  5. EVAP canister is restricted.
  6. EVAP canister vent solenoid is stuck closed.
  7. Restricted EVAP pipes.
  8. High Reid Vapor Pressure (RVP).
  9. High fuel temperature.
  10. The fuel filler hose/pipe is pinched, kinked or blocked.
  11. The fuel feed hose or crossover hose is pinched, kinked or blocked.
  12. The ignition switch is on.

Fuel spit back.

Check the following items

  1. Check valve is stuck open.
  2. Check valve is stuck closed.
  3. Check valve is leaking.
  4. High Reid Vapor Pressure (RVP).
  5. High fuel temperature.

Liquid fuel in the EVAP canister.

Check the following items

  1. Fill limiter vent valve is stuck open.
  2. Fill limiter vent valve is leaking.

Liquid fuel leak.

Check the following items

  1. Pressure relief valve in fill limiter vent valve is stuck open.
  2. Pressure relief valve in fill limiter vent valve is leaking.
  3. Fuel filler hose is loose or torn.
  4. Fuel feed hose or crossover hose is loose or torn.
  5. Fill limiter vent valve is stuck open.

Fuel odor.

Check the following items

  1. Pressure relief valve in fill limiter vent valve is stuck open.
  2. Pressure relief valve in fill limiter vent valve is leaking.
  3. EVAP canister is saturated.

Engine runs unevenly at idle. If bad enough, vehicle will shake. Idle RPM may vary. Engine idles at incorrect RPM.

Check the following items

  1. Search for bulletins.
  2. Verify that PCM grounds are clean, tight and in the proper locations.
  3. Remove and inspect the air filter element for dirt or for restrictions.
  4. Inspect fuel injectors. See «FUEL INJECTOR COIL TEST»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__fuel-injector-coil-test) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  5. Check fuel pressure. See «FUEL SYSTEM PRESSURE TEST»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  6. Inspect for a restricted fuel filter.
  7. Inspect for a contaminated fuel condition.
  8. Ensure that each fuel injector harness is connected to the correct injector/cylinder. Relocate fuel injector harnesses as necessary.
  9. Inspect cause for engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate MAF sensor, blockage on MAF sensor inlet screen, vacuum hoses that are split, kinked or improperly connected, air intake duct that is collapsed or restricted or air filter that is dirty or restricted.
  10. Inspect cause for engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination, or vacuum hoses that are split, kinked or improperly connected.
  11. Inspect crankcase ventilation valve for proper operation. See «EMISSION SYSTEMS & SUB-SYSTEMS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__emission-systems-sub-systems) in SYSTEM & COMPONENT TESTING - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  12. Use a scan tool in order to monitor the Knock Sensor (KS) system for excessive spark retard activity. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  13. Inspect for proper ignition voltage output with Spark Tester (J-26792).
  14. Remove spark plugs and check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.
  15. An improper spark plug gap will cause a driveability problem. Gap spark plugs using a wire gauge gap tool.
  16. Determine the cause of fouling before replacing spark plugs.
  17. Visually and physically inspect secondary ignition for ignition wires arcing to ground or ignition wires for proper routing.
  18. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.
  19. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  20. Inspect for loose ignition coil grounds. See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-system-component-testing-48l-53l-60l-flex-fuel-gasoline__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  21. Inspect engine mechanical for compression, sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excessive oil in combustion chamber, caused by leaking valve seals. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  22. Inspect for incorrect basic engine parts. Inspect camshaft, cylinder heads, pistons, etc.
  23. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in a no-start, a start and stall or an erratic performance.
  24. Inspect the exhaust system for possible restrictions. Inspect for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. Inspect for possible plugged catalytic converters.
  25. Electromagnetic Interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. If a problem exists, inspect routing of secondary ignition wires or high voltage components near the ignition control circuits.
  26. Inspect Park/Neutral Position (PNP) switch circuit.
  27. Inspect for faulty motor mounts.
  28. Inspect intake and exhaust manifold passages for casting flash.

Engine power varies under steady throttle or cruise. Feels like vehicle speeds up and slows down even though accelerator pedal position remains constant.

Check for the following items

  1. Search for bulletins.
  2. Inspect PCM grounds for being clean, tight and in the proper locations.
  3. Verify the driver understands the operation of the transmission Torque Converter Clutch (TCC) and A/C compressor operation as explained in the owner's manual. Inform customer how the TCC and A/C clutch operates.
  4. Inspect HO2S. The HO2S should respond quickly to different throttle positions. If they do not, inspect HO2S for silicone or other contaminates from fuel or use of improper RTV sealant. The sensors may have a White, powdery coating and result in a high but false signal voltage rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem.
  5. Inspect the Mass Airflow (MAF) sensor connections. Repair or replace damaged terminals.
  6. Test for incorrect fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.
  7. Inspect for a restricted fuel filter. See «FUEL SYSTEM DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-48l-53l-60l-flex-fuel-gasoline-engines) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES article.
  8. Inspect for a contaminated fuel condition.
  9. Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
  10. Inspect cause for engine to run rich: Water intrusion in HO2S connector, engine oil contaminated by fuel, EVAP canister purge condition, incorrect fuel pressure, leaking fuel pressure regulator, leaking fuel injectors, inaccurate Mass Airflow (MAF) sensor, blockage on MAF sensor inlet screen, vacuum hoses that are split, kinked or improperly connected, air intake duct that is collapsed or restricted or air filter that is dirty or restricted.
  11. Inspect cause for engine to run lean: Water intrusion in HO2S connector, exhaust leak between HO2S and engine, vacuum leaks, incorrect fuel pressure, restricted fuel injectors, inaccurate MAF sensor, fuel contamination or vacuum hoses that are split, kinked or improperly connected.
  12. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring
  13. Test for proper ignition voltage output with Spark Tester (J-26792).
  14. Remove spark plugs and inspect for correct heat range, wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
  15. An improper spark plug gap will cause a driveability problem. Gap spark plugs using a wire gauge gap tool.
  16. Determine the cause of fouling before replacing spark plugs.
  17. Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 diagnostic procedures for diagnosis. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-flex-fuel-gasoline__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158498-S20484766492003100100000) in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.
  18. Inspect for loose ignition coil grounds.
  19. Verify that the engine coolant temperature is not above 266°F (130°C). This condition causes PCM to operate in Engine Coolant Over Temperature - Fuel Disabled Mode. While in Engine Coolant Over Temperature - Fuel Disabled Mode, the PCM turns fuel OFF to 4 cylinders at a time to keep engine temperatures from reaching damaging levels. The driver may perceive this condition as a lack of power, miss or rough idle.
  20. Inspect for excessive crankshaft end play that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in a no-start, a start and stall, or erratic performance.
  21. Visually and physically inspect vacuum hoses for splits, kinks, and proper connections and routing as shown on the underhood Vehicle Emission Control Information label.
  22. Inspect the transmission Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. A TCC applying too soon can cause the engine to spark knock.

RESTRICTED EXHAUST

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and diagnosis should begin there. To diagnose exhaust system, refer to EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.8L, 5.3L & 6.0L "C", "G", "H", "K", "N", "S" & "T" SERIES - FLEX FUEL & GASOLINE article.

INTERMITTENTS

Note. Intermittent is a DTC or symptom, with a condition that cannot be duplicated.

PRELIMINARY

Perform the Diagnostic System Check - Engine Controls before starting. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article.

HARNESS OR CONNECTOR INTERMITTENTS

Many intermittent open or shorted circuits come and go with harness or connector movement caused by the following type conditions

  1. Vibration.
  2. Engine torque.
  3. Bumps or rough pavement.

Test for intermittents by performing the applicable procedure from the following list

  1. Move related connectors and wiring while monitoring the appropriate scan tool data.
  2. Move related connectors and wiring with the component commanded on and off, with scan tool. Observe the component operation.
  3. With the engine running, move related connectors and wiring while monitoring engine operation.

Verify whether the harness or connector movement affects any of the following systems

  1. Data displayed.
  2. Component or system operation.
  3. Engine operation.

Repair components as necessary.

ELECTRICAL CONNECTIONS OR WIRING

  1. Intermittents are usually caused by one or more of the following conditions: Poor electrical connections. Terminal tension. Wiring problems.
  2. Carefully inspect the suspected circuit for the following conditions: Poor mating of the connector halves. Terminals backed out or not fully seated in the connector body. Improperly formed or damaged terminals. Test for poor terminal tension. Poor terminal-to-wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body. Corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation, with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits. Wires that are broken inside the insulation. Pinched, cut or rubbed-through wiring in harness. Wiring that is in contact with hot exhaust components.
  3. Repair the condition as necessary.

CONTROL MODULE POWER & GROUNDS, & COMPONENT POWER & GROUNDS

Poor power or ground connections can cause widely varying symptoms.

  1. Test all control module power circuits. Many vehicles have multiple circuits supplying power to the control module. Other components in the system may have separate power circuits that may also need to be tested. Inspect connections at the module or component connectors, fuses, and any intermediate connections between the power source and the module or component. A test light or a Digital Volt-Ohmmeter (DVOM) may indicate that voltage is present, but neither tests the ability of a circuit to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component. See POWER DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  2. Test all control module ground and system ground circuits. The control module may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Inspect grounds for clean and tight connections at the grounding point. Inspect the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component. See GROUND DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

TEMPERATURE SENSITIVITY

  1. An intermittent condition may occur when a component or connection reaches normal operating temperature. The condition may occur only when the component or connection is cold, or only when the connection is hot.
  2. The following data may help to diagnose this type of intermittent condition: Freeze Frame/Failure Records. Scan tool snapshot. Vehicle data recorder.
  3. If the intermittent is related to heat, review the following data: High ambient temperatures. Underhood or engine generated heat. Circuit generated heat due to a poor connection, or high electrical load. Higher than normal load conditions, such as towing.
  4. If the intermittent is related to cold, review the following data: Low ambient temperatures. In extremely low temperatures, ice may form in a connection or component. Test for water intrusion. The condition only occurs on a cold start. The condition is not present after the vehicle warms up.
  5. Information from the customer may help to determine if the trouble follows a pattern that is temperature related.

ELECTROMAGNETIC INTERFERENCE & ELECTRICAL NOISE

Some electrical components or circuits are sensitive to Electromagnetic Interference (EMI) or other types of electrical noise. Perform the following procedures

  1. Inspect for a misrouted harness that is too close to a high voltage or high current device. This condition may induce electrical noise on a circuit that could interfere with normal circuit operation. Inspect for wires that are too close to the following devices: Secondary ignition components. Motors. The generator.
  2. Determine whether the electrical system interference is caused by a malfunctioning relay, PCM driven solenoid or switch. These components may cause a sharp electrical surge. Normally, the problem will occur when the malfunctioning component is operating.
  3. Determine whether non-factory or aftermarket add-on accessories are installed in the vehicle. These accessories may lead to an emission related OBD-II failure. Determine if any of the following non-factory or aftermarket add-on accessories is causing the intermittent: Lights. 2-way radios. Amplifiers. Electric motors. Remote starters. Alarm systems. Cellular phones.
  4. Test for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode.
  5. Test for proper performance of the generator. See ON-VEHICLE TESTING in appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
  6. If a DTC is determined to be intermittent and tests do not reveal a problem, see «VEHICLE DATA RECORDER»(/cadillac/escalade/gmt800-2001-2006/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-48l-53l-60l__vehicle-data-recorder) .

INCORRECT PCM PROGRAMMING

  1. There are only a few situations when reprogramming a PCM is appropriate, such as the following: A new service PCM is installed. A PCM from another vehicle is installed. Revised software or calibration files have been released for this vehicle.
  2. Verify that the PCM contains the correct software or calibration. If incorrect programming is found, reprogram the PCM with the most current software or calibration. See POWERTRAIN CONTROL MODULE under PROGRAMMING in appropriate SELF-DIAGNOSTICS article.

DUPLICATING FAILURE CONDITIONS

  1. If none of the previous tests are successful, attempt to duplicate or capture the failure conditions.
  2. Freeze Frame/Failure Records data, where applicable, contains the conditions that were present when the DTC set. Perform the following procedure: Review and record Freeze Frame/Failure Records data. Clear DTCs using scan tool. Turn ignition off and wait 15 seconds. Operate vehicle under the same conditions that were noted in Freeze Frame/Failure Records data, as closely as possible. The vehicle must also be operating within the Conditions for Running DTC. Monitor DTC Status for the DTC being tested. The scan tool will indicate Ran, when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool will also indicate whether the DTC passed or failed.
  3. An alternate method is to drive vehicle with DVOM connected to a suspected circuit. An abnormal reading on the DVOM when problem occurs, may help you locate the problem.

SCAN TOOL SNAPSHOT

The scan tool can be set up to take a snapshot of the parameters available via serial data. The snapshot function records live data over a period of time. The recorded data can be played back and analyzed. The scan tool can also graph parameters singly or in combinations of parameters for comparison. The snapshot can be triggered manually at the time the symptom is noticed, or set up in advance to trigger when a DTC sets. An abnormal value captured in the recorded data may point to a system or component that needs to be investigated further. Refer to scan tool user instructions for more information on the Snapshot function.

VEHICLE DATA RECORDER

The Vehicle Data Recorder (J-42598) is connected to the Data Link Connector (DLC) and sent with customer. The vehicle data recorder captures data for later retrieval and analysis by the technician. Refer to vehicle data recorder user instructions for more information.

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