Engine Controls - Basic Diagnostic Procedures: Other Mazda 6 GG

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. Ensure oil level and condition are okay. Ensure battery is fully charged. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

Exhaust system can be checked with a vacuum or pressure gauge. Remove Heated Oxygen Sensor (HO2S) or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is more than 2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

ENGINE DOES NOT CRANK

1. Check for enabled anti-theft system.
2. Check for hydrolocked engine (liquid in cylinder).
3. Check starting and charging system for correct operation.
4. Check Transmission Range (TR) switch adjustment and operation.
5. Check for locked up flywheel or flexplate.

Repair as necessary.

ENGINE CRANKS BUT WILL NOT START

1. Check fuel tank contents and fuel gauge accuracy. Check for dirt, water or contamination in fuel.
2. Check fuel lines and fittings for leaks. If no leaks are found, check fuel delivery system for proper pressure and volumes. Reset Inertia Fuel Shutoff (IFS) switch (if necessary). Refer to «INERTIA FUEL SHUTOFF SWITCH»(ref-151890-S39865481512003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article.
3. Check for damaged or contaminated fuel injector wiring harness and connector. Ensure fuel injectors pulse when engine is cranked.
4. Check ignition system for strong spark at spark plugs. If spark is not present or if spark is weak, proceed to appropriate SELF-DIAGNOSTICS article.
5. Check engine compression.
6. Check valve timing.
7. Check for overheating engine.
8. Check for intake air system leak.
9. Check operation of Idle Air Control (IAC) valve.
10. Check for damaged or faulty crankshaft pulley and Crankshaft Position (CKP) sensor.

Repair as necessary.

FUEL PRESSURE RELEASE

Note. On Miata, fuel pump relay housing is easily broken when relay is removed. Test relay in place and remove relay only for replacement.

Except B2300, B3000, B4000 & Tribute 3.0L

Remove fuel filler cap, to release fuel tank pressure. Disconnect fuel pump relay 6-pin harness connector, on Miata. On all other models, remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. (Scheme 8)and (Scheme 9). Start engine (if possible) and allow to die. Crank engine several times. Turn ignition off. Reconnect fuel pump relay 6-pin harness connector, on Miata. On all other models, reinstall fuel pump relay.

FUEL PUMP RELAY LOCATIONS

Scheme 8

Scheme 9

FUEL PRESSURE (EXCEPT B2300, B3000, B4000 & TRIBUTE)

After Repair Procedure

Fuel Leakage Inspection

1. Turn ignition on to operate fuel pump.
2. Pressurize fuel system this way for at least 5 minutes to be sure of no leakage.
3. If there is fuel leakage, inspect fuel hoses, hose clamps, and fuel pipe sealing surface and replace if necessary.
4. After repair, reassemble fuel system and repeat steps 1 - 3 .

FUEL PRESSURE (B2300, B3000, B4000 & TRIBUTE)

Fuel Delivery System

1. Check System Integrity Visually inspect complete fuel delivery system, including fuel lines, connections, relays, damage to fuel tank, fuel pump, fuel pressure regulator, fuel pulse damper and fuel injector areas for leaks, looseness, cracks, kinks, pinching, or abrasion caused by a collision or mishandling. Visually inspect electrical harnesses and connectors for loose pins, corrosion, abrasion, or other damage from collision or mishandling. Verify vehicle has followed maintenance schedule. Verify fuel pump shutoff switch is set. Verify battery is fully charged (12.5 volts or more). Verify electrical/fuse integrity. Verify fuel level is sufficient. If concern is not present, go to next step. If any concern is found, repair as necessary. After repair, rerun Quick Test. See QUICK TEST under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
2. Check For Voltage At Fuel Pump Harness Connector Connect scan tool to DLC-2. Verify fuel pump shutoff switch state. Follow fuel pump shutoff switch reset procedure. Refer to «INERTIA FUEL SHUTOFF SWITCH»(ref-151890-S39865481512003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article. Disconnect fuel pump assembly 4-pin harness connector at fuel pump. Turn ignition on, engine off. Connect a DVOM between fuel pump power circuit (Pink/Black wire) and fuel pump ground circuit (Black wire) at fuel pump assembly 4-pin harness connector. see scheme 7or see scheme 8. Enter OUTPUT TEST MODE to turn on fuel pump circuit and monitor voltage reading. If voltage reading is more than 12.5 volts, exit OUTPUT TEST MODE. Reconnect fuel pump 4-pin harness connector. Restore vehicle to original condition. Go to next step. If voltage reading is not more than 12.5 volts, check for opens and shorts in fuel pump power and ground circuits. Repair as necessary. After repair, restore vehicle to original condition.
3. Check Fuel Filter For Proper Maintenance Locate and inspect vehicle maintenance schedule and fuel filter. Check for last service date. If fuel filter was serviced in last 1000 miles, go to next step. If fuel filter was not serviced in last 1000 miles, replace fuel filter. After repair, go to next step. WARNING: Before servicing or replacing any components in fuel system, reduce possibility of injury or fire by following directions in fuel system warning at beginning of this test.
4. Check Fuel Pressure Install fuel pressure tester. Release fuel pressure. Connect scan tool to DLC-2. Turn ignition on, engine off. Access OUTPUT TEST MODE and run fuel pump to obtain maximum fuel pressure. For fuel pressure specifications, see «FUEL SYSTEM»(ref-151873-S08065964082003010800000) in SERVICE & ADJUSTMENT SPECIFICATIONS article. NOTE: Fuel pump will only operate for approximately 8 seconds when Output Test Mode is selected and activated. If fuel pressure reading is as specified, go to next step. If fuel pressure reading is not as specified: If fuel pressure reading is more than specified, replace fuel pump. After repair, restore vehicle to original condition. Recheck fuel pressure. If fuel pressure reading is less than specified, go to step 7.
5. Check Fuel Injector Flow And Leakage Check fuel injectors for leakage and flow rate using an injector tester: Flow Rate Specification 2.3L engine - 9.5 kg/hr (21 lb/hr). 3.0L engine - 5.5 kg/hr (12 lb/hr). 4.0L engine - 8.7 kg/hr (19 lb/hr). If flow rate and leakage rate for injectors tested is as specified, verify no other leak exists and replace fuel pump. If flow rate and leakage rate for injectors tested is not as specified, replace faulty fuel injector(s). After repair, restore vehicle to original condition. Recheck fuel pressure.
6. Check Pulse Damper/Fuel Pressure Regulator Diaphragm Install fuel pressure tester. Start engine and run engine for 10 seconds. Turn ignition on, engine off. Wait 10 seconds. Start engine and run engine for 10 seconds. Turn ignition off. Remove vacuum hose from pulse damper port (fuel pressure regulator port, on Tribute) and inspect for fuel in vacuum hose. If vacuum hose and pulse damper port (fuel pressure regulator port, on Tribute) are free of fuel, go to next step. If fuel is found in vacuum hose, pulse damper port or fuel pressure regulator port, replace pulse damper or fuel pressure regulator. WARNING: Before servicing or replacing any components in fuel system, reduce possibility of injury or fire by following direction in fuel system caution, handling and warning at beginning of this test.
7. Check Fuel Supply Line For Restriction Release fuel pressure. Disconnect fuel supply line at fuel rail. Disconnect fuel supply line at fuel pump. Check for restriction in fuel supply line (blockage, kinked or pinched). Using regulated air pressure of 3-5 psi (21-34 kPa), blow air through fuel supply line. If air flows freely, replace fuel pump. If air does not flow freely, repair restriction as necessary. Restore vehicle back to original condition and recheck fuel system.

IGNITION CHECKS

Note. Perform following tests in sequence shown, unless test procedures indicate otherwise. For the following test, the term Electronic Ignition (EI) may be used to describe the ignition system.

Spark Check

Remove spark plug. Connect spark plug to high-tension lead and hold about 1/4 inch from ground. Crank engine and verify a strong Blue spark is discharged. If spark is not present, measure spark plug wire resistance on suspect wire. Resistance should be less than 16,000 ohms per 3.28 feet. Replace spark plug wire and spark plug as necessary.

Camshaft Position Sensor

See CAMSHAFT POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article.

Crankshaft Position Sensor

See CRANKSHAFT POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article.

See CAMSHAFT POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article.

See CRANKSHAFT POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article.

Ignition Coil Resistance (B2300, B3000, B4000 & Tribute)

For ignition coil resistance testing procedure, see INTEGRATED IGNITION COIL DTCS P0351-P0356 under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

1. Perform self diagnostic QUICK TEST to check for ignition-related fault codes, and repair as necessary. See QUICK TEST in appropriate SELF-DIAGNOSTICS article. If no fault codes are retrieved, check ignition system wiring harness connectors for corrosion and tight fit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. Clean or repair connectors as necessary.
2. If wiring and connectors are okay, use Spark Tester (303-D037 or D8IP-6666-A) to check for spark at each spark plug wire while cranking engine. If Blueish-White spark is present at each cylinder, ignition system is okay. If Blueish-White spark is not present at each cylinder, inspect spark plugs at missing cylinders. Measure resistance of spark plugs. Replace spark plug if resistance reading is less than 2000 or more than 20,000 ohms.

IDLE SPEED & IGNITION TIMING

Connect scan tool to DLC-2. Ensure idle speed and base ignition timing are set to specification. See IDLE SPEED SPECIFICATIONS and IGNITION TIMING SPECIFICATIONS tables. If adjustment is necessary, see ON-VEHICLE ADJUSTMENTS article.

IDLE SPEED SPECIFICATIONS

IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM)

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate SELF-DIAGNOSTICS article. If no hard codes are found in self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.