Lack/Loss Of Power

DETECTION CONDITION AND POSSIBLE CAUSE

9	LACK/LOSS OF POWER
DESCRIPTION	Performance poor under load (i. e., power down when climbing hills)

LACK/LOSS OF POWER INSPECTION

STEP	INSPECTION		ACTION
1	PRELIMINARY CHECKS NOTE: Verify symptom is reported under normal driving conditions without excessive engine/vehicle load conditions. Perform the following preliminary checks: Vacuum lines (check for damage and proper routing). Intake air system (Check for damaged tubes and dirty air filter). Vehicle wiring (disconnected, corroded/damaged). Throttle linkage. Radiator (obstructed). Transmission (fluid check). Be aware of the over RPM/speed limiting functions of the PCM. Are all checks OK?	Yes	Go to step 2.
1		No	Service as required. Verify symptom no longer exists.
2	PERFORM PCM QUICK TEST Are any DTCs displayed during Continuous Memory, Key ON, Engine OFF (KOEO) or Key ON, Engine Running (KOER) Self Tests?	Yes	Check for cause, See DIAGNOSTIC TROUBLE CODE NUMBERS .
2		No	Go to step 9.
3	CHECK PIDS Connect NGS Tester. Check following PIDS. DPFEGR, ECT, IAC, LONGFT1, LONGFT2, VPWR. See PIN VOLTAGE/PID VALUE CHARTS article. Are PIDS within specification?	Yes	Go to step 4.
3		No	Service as required.
4	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 5.
4		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.
5	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 6.
5		No	Check fuel supply line for restriction.
6	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 7. If not OK, clean or replace spark plugs.
6		No	Check following: High-tension leads. CKP sensor. TEST 8: CRANKSHAFT POSITION (CKP) SENSOR . CMP sensor CAMSHAFT POSITION (CMP) SENSOR MALFUNCTION .
7	CHECK EXHAUST SYSTEM Is there a restriction in the exhaust system?	Yes	Service as required.
7		No	Go to step 8.
8	CHECK BASE ENGINE Check for base engine concerns (such as improper compression, worn camshaft/valve train, gasket leaks). See ENGINE COMPONENT TESTS . Is a fault indicated?	Yes	Service as required.
8		No	Go to step 9.
9	CHECK AUTOMATIC TRANSMISSION (A/T) If vehicle has manual transmission, go to step 10. See DIAGNOSIS - 4R44E or DIAGNOSIS - 5R55E for automatic transmission concerns. Is automatic transmission OK?	Yes	Go to step 10.
9		No	Service as required.
10	CHECK FOR BRAKE SYSTEM CONCERNS See DISC & DRUM for brake concerns (such as drag or binding). Is a fault indicated?	Yes	Service as required.
10		No	Go to step 11.
11	CHECK FOR LACK OF A/C CUTOFF UNDER WOT CONDITIONS (APPLICATIONS WITH WOT A/C CUT-OFF RELAY) See A/C DOES NOT CUT-OFF UNDER WIDE OPEN THROTTLE CONDITIONS . Does the A/C cut off under WOT conditions?	Yes	Go to step 12.
11		No	See A/C DOES NOT CUT-OFF UNDER WIDE OPEN THROTTLE CONDITIONS .
12	ADDITIONAL CHECKS Additional checks: Customer driving habits (such as excessive loads or over RPM/speed limiting functions enabled). Ignition base timing (if not previously checked). Clutch (IWT). Charging system. Are all checks OK?	Yes	Go to step 13.
12		No	Service as required. Verify symptom no longer exists.
13	Verify test results. If OK, See DIAGNOSTIC INDEX to service any additional symptoms