Knocking / Pinging

DETECTION CONDITION AND POSSIBLE CAUSE

10	KNOCKING /PINGING
DESCRIPTION	Sound produced when air/fuel mixture is ignited by something other than spark plug

KNOCKING / PINGING INSPECTION

STEP	INSPECTION		ACTION
1	PRELIMINARY CHECKS Perform the following preliminary checks: Vacuum lines. Fuel (concerns such as fuel quality and proper grade). Engine overheating. Intake air system. Are all checks OK?	Yes	Go to step 2.
1		No	Service as required. Verify symptom no longer exists.
2	CHECK IF ENGINE IS OVERHEATING NOTE: With the engine running and temperature stabilized, the ECT PID should be greater than.30 volt (temperature less than 116°C/240°F). Does the engine appear to be overheating?	Yes	Engine is overheating. See ENGINE COOLING SYMPTOM CHART .
2		No	Go to step 3.
3	PERFORM PCM QUICK TEST Are any DTCs displayed during Continuous Memory Self Tests, Key ON, Engine OFF (KOEO) or Key ON, Engine Running (KOER)?	Yes	Check for cause. See DIAGNOSTIC TROUBLE CODE NUMBERS .
3		No	Go to step 9.
4	CHECK BASE ENGINE Check for base engine concerns (such as improper compression, worn camshaft/valve train, gasket leaks), See ENGINE SYMPTOM CHART . Is a fault indicated?	Yes	Service as required.
4		No	Go to step 5.
5	CHECK FUEL DELIVERY SYSTEM Perform fuel pressure INSPECTION. See TEST 11: FUEL LINE PRESSURE / FUEL PRESSURE HOLD INSPECTION . Fuel line pressure: 386-496 kPa (56-72 psi), 3.0L flexible fuel 380-517 kPa (55-75 psi) Is fuel pressure correct?	Yes	Go to step 6.
5		No	If pressure is greater than 496 kPa (72 psi), 3.0L flexible fuel 517 kPa (75 psi): Replace fuel pump. See FUEL PUMP in REMOVAL, OVERHAUL, AND INSTALLATION article in Engine Performance . If pressure is less than 386 kPa (56 psi), 3.0L flexible fuel 380 kPa (55 psi): Check fuel supply line for restriction.
6	CHECK FUEL DELIVERY SYSTEM Check fuel pump fuel flow. See TEST 5: FUEL DELIVERY SYSTEM . Did fuel system flow the required amount of fuel?	Yes	Check injector for leakage, See TEST 12: FUEL INJECTOR INSPECTION . If injector leaks, service as necessary. See FUEL RAILS & INJECTORS in REMOVAL, OVERHAUL, AND INSTALLATION article in Engine Performance . If injector OK, go to step 7.
6		No	Check fuel supply line for restriction.
7	CHECK SECONDARY IGNITION SYSTEM Is strong blue spark visible at each disconnected high-tension lead while cranking engine?	Yes	Check spark plugs: If OK, go to step 8. If not OK, clean or replace spark plugs.
7		No	Check following: High-tension leads. CKP sensor. See TEST 8: CRANKSHAFT POSITION (CKP) SENSOR . CMP sensor, CAMSHAFT POSITION (CMP) SENSOR MALFUNCTION .
8	CHECK PCV SYSTEM Remove PCV valve and shake it. Does PCV valve rattle?	Yes	Install PCV valve. Go to step 9.
8		No	Replace PCV valve,
9	CHECK PCV SYSTEM Start engine and bring to normal operating temperature. Disconnect crankcase ventilation hose from throttle body. Place a stiff piece of paper over the hose. Wait one minute. Does vacuum hold paper in place?	Yes	Go to step 10.
9		No	Disconnect evaporative hose. Place a stiff piece of paper over the hose. Wait one minute. Does vacuum hold paper in place? If yes, See EVAPORATIVE EMISSION (EVAP) MONITOR AND SYSTEM MALFUNCTION step 9. If no, check for vacuum leaks, obstructions in the PCV system, oil cap, PCV valve, rocker cover bolt torque/gasket leak. Service as required.
10	ADDITIONAL CHECKS Additional checks: Ignition base timing (if not previously checked). Intake air system. Engine oil quality. Are all checks OK?	Yes	Go to step 11.
10		No	Service as required. Verify symptom no longer exists.
11	Verify test results. If OK, See DIAGNOSTIC INDEX to service any additional symptoms