PleasureCraft Engine Group 5.0L, Diagnostic Manual, Page: 308 / 337

7 - 12 Symptoms 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
Hesitation, Sag, Stumble Symptom
Step Action Value Yes No
Defi nition: Momentary lack of response as the accelerator is pushed down. Can occur at all vehicle speeds.
Usually most severe when fi rst trying to make the vehicle move, as from a stop. May cause engine to stall
if severe enough.
1
Was the “On-Board Diagnostic (OBD) System Check” Go to OBD
performed? — Go to Step 2 System Check
2
Was visual/physical check performed? Go to Visual/
— Go to Step 3 Physical check
1. Check for correct base ignition timing.
•
Refer to “Ignition Timing Set Procedure” in the
3
Distributor Ignition section.
2. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 4
1. Check for contaminated fuel.
4
2. Check fuel fi lters and water separator.
3. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 5
1. Check for proper fuel pressure while the condition exists.
5
•
Refer to Table A-4.
2. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 6
1. Check fuel injectors.
•
Refer to Injector Coil Test and Injector Balance
6
Test at the end of this section.
2. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 7
1. Check for proper operation of Ignition Control (IC)
7
circuit and the Knock Sensor (KS) circuit(s).
2. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 8
1. Check integrity of the primary and secondary wiring.
2. Check routing of the wiring.
8
3. Check condition of IC module, pick-up coil, distributor
cap, rotor and spark plug wires.
4. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 9
1. Remove spark plugs and check for wet plugs, cracks,
wear, improper gap, burned electrodes or heavy
deposits.
•
Refer to Table A-6.
9
Notice: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary. Go to OBD
Was a problem found? — System Check Go to Step 10