Rough idle and slow crank with no start when hot

DELANEY877

MEMBER
1994 FORD MUSTANG
3.8L
V6
2WD
MANUAL
220,000 MILES

Okay, so I got the car listed above, guy said he rebuilt the engine. When I got it passenger side head gasket was faulty I replaced head gaskets and all upper gasket. Also new oil pump, water pump, coil pack, plugs and wires, fuel filter. When cold car cranks and runs 1,000 rpm's runs okay. Anything lower runs rough when engine gets to operating temperature it wants to stall or if shut off. It will crank slowly like a dead battery and when jumped off not much different and will not start but spit and sputter. Please help

Wednesday, March 13th, 2019 AT 7:22 PM

1 Reply

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

This could be a problem with your vehicle's Ignition Control Module (ICM), This module gets a signal from the Crankshaft Position Sensor about where the engine is in its cycle and then produces a Profile Ignition Pick up (PIP), which is sent to the Power-train Control Module (PCM) AKA, "computer". The PCM then sends a Spark Output (SPOUT) back to the ICM which it uses to fire the appropriate spark plug via the spark plug wire. It also sends a signal back to the PCM which is used for the vehicle's tachometer.
When the ICM or its corresponding electrical connectors or wiring goes bad it will cause intermittent faults, rough running, stalling, and long crank, hard start situations. I have included in the diagrams below a Technical Service Bulletin (TSB) from Ford that might be of interest to you as well as the component location of the ICM. Please check the ICM and get back to us with what you find out.

Thanks,
Alex
2CarPros

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