Engine "skips"

[rogela]

I have a 94 E-150 with 5.8L engine. The van is a wheelchair van. While driving the engine "skips" as if a spark plug didn't fire. Sometimes, while idling in DRIVE it stalls but restarts immediately.

A major tune up was done in September 2005 at a Ford dealer. It had a fault code of P0121 and the throttle body and sensor were replaced.

I researched the current problem and the "faulty" TFI module problem seemed to describe what was happening.

I took it to a Ford dealer and so far they have replaced the TFI module, the distributor and the spark plugs and claim they have checked the wiring for shorts and other visible signs of wear.

The ABS light on the dashboard is also on all the time but I don't know if that applies to the current problem except that it might point to a short somewhere and something related to the EEC is also loose and only causes the "skip" where it is jostled while driving. The Ford delaer says that it also "skips" while idling in the shop.

Currently they are "shotgunning" for potential areas before replacing the PCM.

Any help would be appreciated.

TIA - Jim

[subford]

I take it they did not own an Analog voltmeter to check the voltage before they changed all of that out.
If they did they could have checked to see if the voltage for TPS was between .95 and 4.95 Volts and moving smoothly across the scale to see if it was bad or not. Did they use a breakout box?
I would say spark plug wire or an injector is bad, I do not see a PCM as being the problem.
Did they do a compression check?
A vacuum leak could also do this.

[rogela]

New spark plug wires last September. The injectors and the fuel filter were cleaned recently.

Vacuum leak? I thought that's what the PIP/TFI/PCM did away with? Never-the-less I'll ask the mechanic in the morning.

Thanks - Jim

[subford]

Originally Posted by rogela

New spark plug wires last September. The injectors and the fuel filter were cleaned recently.

Vacuum leak? I thought that's what the PIP/TFI/PCM did away with? Never-the-less I'll ask the mechanic in the morning.

Thanks - Jim

The PIP/TFI/PCM have nothing to do with vacuum.

PIP - Profile Ignition Pickup
TFI - Thick Film Ignition system
PCM - Powertrain Control Module

[Franklin2]

I am sure they have put a code reader/scanner on it? I would start looking for something unusual like water in the fuel or something like that.

[rogela]

After replacing the TFI module (caused stall while idling in Drive) and the distributor and a whole lot of checking wiring, injectors with an ocilliscope, etc. they called in a Ford engineer. The consensous was the PCM. The PCM was replaced and it runs great!

Thanks for all your help.