wgebb

Hey guys,

Been having issues with my '96 4.0 Manual Trans for 3 months now and it's really starting to get me down because I can't figure out what's the issue.

Symptoms:
Initially, when up to operating temp, ignition was lost and engine would die softly like I turned the key off. After replacing Crank Sensor, at operating temp it would still lurch sometimes like it lost power for just a second then it would start firing again. Now today after about 30 minutes of idling it did the same thing, started to lose power then caught itself, throttled way up but went back to idling shortly. About 10 minutes later it started to die and the vehicle choked and shook for a few seconds so I turned the key off.

Things I have done:
1. Replaced Crank Sensor with OEM part.
2. Cleaned engine grounds (3 of them)
3. Checked fuel pressure at the rail. Good.
4. Replaced ignition coil.
5. Replaced dizzy cap and pickup sensor.
6. Cleaned throttle body.
7. Unplugged and sprayed all the electrical connectors I could find.
8. Replaced PCM with junkyard part, no change in behavior so I flashed the memory on it but that did nothing either. I have since put original PCM back on.
9. Replaced fuel filter.
10. New Downstream O2 sensor. Voltage ranges are good on both banks when vehicle is running.

Vacuum pressure at idle hovers around 22 in/Hg, and behaves properly when throttle snaps shut after high RPM. OBDII + Torque app reads no fault codes. Fuel pump makes an electrical whine/buzzing sound when on, which I have never noticed before but it was not on my mind either. I have not tested fuel pump directly but with 48psi at the rail I thought it safe to rule that out.

Any input is greatly appreciated. Been snooping around this forum for a couple months new looking at people with similar symptoms but to no avail in terms of a solution. A buddy of mine thinks it could be injector drip, so I think my next move is to remove the rail and have a look at those.