Engine Poor DRIVEABILITY

ENGINE POOR DRIVEABILITY DESCRIPTION

7	ENGINE STALLS/QUITS ENGINE RUNS ROUGH MISSES BUCK/JERK HESITATION/STUMBLE ACCELERATION SURGES ROLLING IDLE
DESCRIPTION	Engine stops unexpectedly at beginning of acceleration or during acceleration. Engine stops unexpectedly while cruising. Engine speed fluctuates during acceleration or cruising. Engine misses during acceleration or cruising. Vehicle bucks/jerks during acceleration, cruising or deceleration. Momentary pause at beginning of acceleration or during acceleration. Momentary minor irregularity in engine output.

ENGINE STALLS/QUITS
ENGINE RUNS ROUGH
MISSES
BUCK/JERK
HESITATION/STUMBLE
ACCELERATION SURGES
ROLLING IDLE

DESCRIPTION

Engine stops unexpectedly at beginning of acceleration or during acceleration.
Engine stops unexpectedly while cruising.
Engine speed fluctuates during acceleration or cruising.
Engine misses during acceleration or cruising.
Vehicle bucks/jerks during acceleration, cruising or deceleration.
Momentary pause at beginning of acceleration or during acceleration.
Momentary minor irregularity in engine output.

ENGINE POOR DRIVEABILITY INSPECTION/ACTION CHART

STEP	INSPECTION		ACTION
1	PRELIMINARY CHECKS Perform the following preliminary checks: Vacuum lines (routing, integrity). Air filter (restricted). Intake air tubes (leaks, restrictions). Proper sealing of intake manifold and components attached to intake air (such as EGR valve or IAC valve). Ignition wiring. Fuel quality (concerns such as proper octane, contamination, winter/summer blend). Electrical connections. Be aware of the over rpm and speed limiting functions of the PCM. Are all checks OK?	Yes	Go to next step.
1		No	Service as required. Verify symptom no longer exists.
2	CHECK FOR STALL AT IDLE (PARK/NEUTRAL) Does engine now stall at idle in PARK/NEUTRAL?	Yes	Engine stalls now. Go to step 5.
2		No	Go to next step.
3	CHECK FOR ROUGH IDLE (PARK/NEUTRAL) Does engine idle rough in PARK/NEUTRAL?	Yes	Engine idles rough. Go to step 7.
3		No	Go to next step.
4	PERFORM PCM QUICK TEST See 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 .
4		No	Go to step 9.
5	ENGINE STALLS NOW: PERFORM PCM KOEO SELF-TEST. ALSO RETRIEVE ANY CONTINUOUS MEMORY DTCs Retrieve and record Continuous Memory DTCs. Perform KOEO Self-Test. See PCM QUICK TEST . Are any DTCs displayed?	Yes	Check for cause. See DIAGNOSTIC TROUBLE CODE NUMBERS .
5		No	Go to next step.
6	IDLE AIR CONTROL (IAC) CHECK Attempt to start engine at part throttle. Does engine start and run smoothly at part throttle?	Yes	Possible IAC concern. Go to step 2, IDLE AIR CONTROL (IAC) VALVE ASSEMBLY MALFUNCTION .
6		No	Go to step 10.
7	ROUGH IDLE: PERFORM PCM KOEO SELF-TEST. ALSO RETRIEVE ANY CONTINUOUS MEMORY DTCs Retrieve and record Continuous Memory DTCs. Perform KOEO Self-Test. See PCM QUICK TEST . Are any DTCs displayed?	Yes	Check for cause. DIAGNOSTIC TROUBLE CODE NUMBERS .
7		No	Go to next step.
8	IDLE AIR CONTROL (IAC) CHECK Start engine and let idle. While checking for rpm drop or engine stall, disconnect IAC valve. After testing turn key off and reconnect IAC valve. Did rpm drop or engine stall when the IAC valve was disconnected?	Yes	IAC passes. Go to next step.
8		No	Go to step 1, IDLE AIR CONTROL (IAC) VALVE ASSEMBLY MALFUNCTION .
9	CHECK PIDS Reconnect WDS or equivalent tester. Check following PIDS. DPFEGR, ECT, IAC, LONGFT1, LONGFT2, VPWR. See POWERTRAIN CONTROL MODULE (PCM) INSPECTION . Are PIDS within specification?	Yes	Go to next step.
9		No	Service as required.
10	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 next step. If not OK, clean or replace spark plugs. See IGNITION COIL-ON-PLUG AND SPARK PLUG -- 2.3L , or IGNITION COIL-ON-PLUG AND SPARK PLUG -- 3.0L (4V) .
10		No	Check following: High-tension leads. CKP sensor. See CRANKSHAFT POSITION (CKP) SENSOR MALFUNCTION . CMP sensor. See CAMSHAFT POSITION SENSOR (CMP) MALFUNCTION .
11	CHECK FUEL DELIVERY SYSTEM Perform fuel pressure inspection. See TEST 9: FUEL LINE/FUEL PRESSURE HOLD INSPECTION . Fuel line pressure: 240 - 380 kPa (35 - 55 psi) Is fuel pressure correct?	Yes	Go to next step.
11		No	If pressure is greater than 380 kPa (55 psi): Replace fuel pump. See FUEL PUMP MODULE . If pressure is less than 240 kPa (35 psi): Check fuel supply line for restriction.
12	CHECK FUEL DELIVERY SYSTEM Check fuel pump fuel flow. See TEST 4: FUEL DELIVERY SYSTEM . Did fuel system flow the required amount of fuel?	Yes	Check injector for leakage. See TEST 10: FUEL INJECTOR INSPECTION . If injector leaks. See FUEL INJECTORS . If injector OK, go to next step.
12		No	Check fuel supply line for restriction.
13	CHECK EXHAUST SYSTEM See EXHAUST SYSTEM CONCERNS . Is there a restriction in the exhaust system?	Yes	Service as required.
13		No	Go to next step.
14	CHECK PCV SYSTEM Remove PCV valve and shake it. Does PCV valve rattle?	Yes	Install PCV valve. Go to next step.
14		No	Replace PCV valve. See POSITIVE CRANKCASE VENTILATION (PCV) VALVE -- 2.3L .
15	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 next step.
15		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) 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.
16	CHECK TRANSAXLE (A/T ONLY) If vehicle has manual transaxle, go to next step. If vehicle has automatic transaxle, go to TROUBLESHOOTING for Diagnostic Strategy. Is automatic transaxle OK?	Yes	Go to next step.
16		No	Service as required.
17	CHECK EVAP SYSTEM Check EVAP system. If symptom is "engine stalls," See CANISTER VENT (CV) SOLENOID MALFUNCTION step 8. For other symptoms, see EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION step 1. Is a fault indicated?	Yes	Service as required.
17		No	Go to next step.
18	CHECK BASE ENGINE Check engine compression. Is engine compression correct?	Yes	Go to next step.
18		No	Service as required.
19	CHECK INTAKE AIR SYSTEM Check intake air system (for the following symptoms only: Stalls/quits at idle, runs rough at idle, rolling idle or symptoms associated with a sticking throttle body) See LOW IDLE/STALLS DURING DECELERATION . Is a fault indicated?	Yes	Service as required.
19		No	Go to next step.
20	ADDITIONAL CHECKS Additional checks: Driveline. Transaxle/clutch (M/T). Charging system. A/C system (for surge with A/C on). Cruise control system (for surge with cruise control on). A/C compressor diode (for rolling idle and/or stumble when A/C cycles on). Are the checks OK?	Yes	Go to next step.
20		No	Service as required.
21	Verify test results. If OK, DIAGNOSTIC INDEX to service any additional symptoms.