Dfi Tests W/o Codes Cadillac Eldorado IX

TROUBLE SHOOTING

Note. Information on this system is also covered in the FUEL SYSTEMS section. Additional diagnostic information that relates strictly to the fuel portion of this system can be found in the DIGITAL FUEL INJECTION article in the FUEL SYSTEMS section.

The Digital Fuel Injection (DFI) system combines engine control, fuel metering and emission monitoring into a computer- controlled system. The Electronic Control Module (ECM) is the "brain" of the DFI system. The ECM is a digital electronic computer which receives and processes engine data, computes and interprets engine information, and sends instructions to various components. It provides fuel efficient operation with reduced exhaust emissions.

HOW TO USE THIS ARTICLE

This portion of the article is used only AFTER you have checked that

1. The On-Car Diagnostics are working.
2. No trouble codes are stored, or only intermittent ones.
3. Ensure that fuel control system is operating properly.
4. Ensure that "Field Service Mode Check" of "DFI System Check" found no problems. Refer to the DFI ECM TESTS/CODES (all models) and/or DFI BCM TESTS/CODES (DeVille & FWD Fleetwood) article in this section.
5. Ensure that a careful visual check found no obvious problems.

Verify the customer's complaint and locate the correct symptom below. Check the items indicated under that symptom. These procedures will normally lead you to a component system on the vehicle, such as EGR, EST, TCC, etc. These are covered in the Component System charts.

INTERMITTENT "SERVICE NOW/SOON" LIGHT

"SERVICE NOW/SOON" light comes on at all times, but does not stay on. A stored code may or may not exist.

Possible Cause & Correction

1. Check for poor mating of one connector to another. Terminals may not be fully seated. Check for improperly formed or damaged terminals. Check wire to terminal connections.
2. Check for poor connection from ignition coil to ground, or arcing at spark plug wires or plugs.
3. Check wires for "SERVICE NOW/SOON" lights to ECM for short to ground.
4. Check for loose or improperly connected body ground and engine grounds.
5. Check for loss of trouble code memory. To check this: Disconnect TPS and idle engine until "SERVICE SOON" light comes on. Code "22/E22" should be stored and retained in memory when ignition is turned off. If not, ECM is faulty.
6. Check for electrical system interference caused by a defective relay or an ECM driven solenoid or switch. They can cause a sharp electrical surge. This type of problem will normally occur when faulty component is operated.
7. Check for improper installation of electrical accessories such as auxiliary lights, or 2-way radio.
8. Make sure that EST wires are kept away from spark plug wires, distributor wires, distributor housing, ignition coil, and generator. Make sure that ground wire from ECM to distributor is connected to a good ground.

HARD START

Engine cranks okay, but does not start for a long time. Engine eventually starts and runs okay. If engine starts, but immediately dies, see "NO START OR STALL AFTER START" chart.

1. Check fuel system, including fuel lines, injectors, fuel pump, and fuel pump relay. Also check for water contamination.
2. If hard start occurs in warm climate or after a "hot soak", check for winter grade fuel or high alcohol content fuel. May be vapor lock.
3. Check ignition timing, HEI voltage output, spark plug wire resistance, and EST operation. Check ignition system for worn or loose gear; worn or bent shaft; cap and rotor for moisture, cracks, dust, carbon tracking, etc.; pickup coil and ignition coil for proper connections.
4. Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes, heavy carbon deposits, and type and heat range.
5. Check for accuracy and high resistance of CTS and MAT sensors and circuits. Check terminals for corrosion and damage. Repair harnesses, or replace sensors as required.
6. Check MAP sensor for restrictions in hose going to throttle body. Check for vacuum trapped in MAP sensor. Clean out, repair or replace MAP hose, and replace sensor as required.

STALLS AFTER STARTING

Engine starts okay, but dies after brief idle, dies as soon as any load is placed on engine (such as turning on A/C or engaging transmission), or on initial driveaway.

1. Make sure that hot air tube is connected to air cleaner.
2. Check for proper operation of thermostatic air cleaner.
3. Check for proper EFE operation.
4. Check PCV valve for proper operation by placing finger over inlet hole in valve. Valve should snap back. If not, replace valve.
5. Check EGR system for proper operation.
6. Check for correct fuel pressure of 9-12 psi in all speed ranges.
7. If stall occurs when A/C is turned on, check for A/C clutch signal to ECM terminal 21 (BCM terminal 21 on FWD DeVille and Fleetwood). Voltage at terminal should be battery voltage when A/C is on and compressor clutch is engaged.
8. Check for an overcharged A/C system, and/or high A/C head pressure that could be caused by inoperative engine cooling fan(s).
9. Check ignition timing, EST operation, pickup coil, and weak spark from faulty ignition coil.
10. Check for plugged, or restricted fuel lines.

HESITATION, SAG, STUMBLE

This is defined as a momentary lack of response as the accelerator is pushed down. It can occur at all vehicle speeds. Usually it is most severe when first trying to make car move, as from a stop sign. Condition may be severe enough to cause vehicle to stall.

1. Check for proper operation of thermostatic air cleaner.
2. Check for proper EFE operation.
3. Check for correct fuel pressure of 9-12 psi in all speed ranges. Also check for contaminated fuel.
4. Check vacuum hose to MAP sensor for leaks or restrictions, and restrictions at MAP port on throttle body: Tee vacuum gauge into MAP hose at sensor. Gauge reading and parameter value (.0.2/ P.0.2) should be about the same and respond quickly to changes in engine load.
5. Check for fouled, cracked, or defective spark plugs or spark plug wires.
6. Check for correct PROM number (parameter .1.3/P.1.3).
7. Check TPS for binding or sticking.
8. Check ignition timing.
9. Check for proper operation of EGR system.
10. Check fuel injectors: With injector connectors disconnected, check for fuel leakage from injectors while cranking. Reconnect injector connectors. Also check injector spray patterns.
11. Check for open in HEI ground circuit.
12. Check for proper operation of canister purge system.
13. Check for carboned, or sticking valves.
14. Check for restricted exhaust and catalytic converter.

ADJUSTMENTS

Note. For adjustment procedures, refer to the V8 TUNE-UP article in the TUNE-UP section.