Motor cutting out while driving

[keith haw]

I hope I can explain this. While driving around it seems like the motor cuts out. Almost like you switch it off and back on real quick.
It also does it sometimes when you let off the gas and then step on it again. Sometimes it even does it when you take off from a stop. This just started. It has a fairly new TPS and MAP. Any ideas?
Thanks
Keith

Guess I should add it's a 87 4.0/AW4

[yuppiexj]

Check the ground on your Crank Position Sensor.

[Eagle]

Another vote for the CPS

[keith haw]

Man ya'll are quick.. OK where might I find it?
Keith

[91xjtim]

I believe its on the back of the block. I believe it read the flywheel. It has two bolts holding it in. And itll have wires coming off of it:)

[willysnut]

Yes It's on the back of the block on the drivers side(mounts thru a cutout in the bellhousing). The wiring is the two wire connector on the top side (close to temp sensor at the rear of the head) of the intake manifold. I had the same problem and replaced it (two bolts). Also have had a camshft position sensor go mammaries up, it's under your rotor in the distrib check that. You'll have to replace the distrib to fix that $65 at Auto Zon.

[keith haw]

Thanks WillysNut. Now I know what I'm looking for.

Keith

[Ron Hyslop]

My daughter's boy friends brother bought a used 87xj with what sounds like an identiacal problem. It turns out the distributor was installed one tooth in the wrong direction. We re-indexed the distributor and it ran perfectly ever after. There was a factory bullitan issed on the subject.

[Bill-93XJ]

I had IDENTICAL symptoms just after the AAMCO boys removed/replaced my tranny. I think they stressed-broke the wires in the harness to the CPS. A new sensor totally cured the problem. If you are looking forward, the unit is in the 10 o'clock position on the bellhousing held by two 10mm bolts. Using an eighteen inch extension and a swivel, I was able to easily remove it with a 3/8 drive socket wrench. Good Luck !!!

[keith haw]

Well here's what's been done so far.
1. Replaced wires/cap and rotor. Helped some but still cuts out.
2. Replaced CPS. No noticeable difference.
3. Cleaned and adjusted TPS, Also cleaned throd body. Helped but still cutting out.
It doesn't do it off idle anymore and it's more like hesitation than cutting out. It can be going at any set speed and start doing it.

Anymore ideas?

Thanks
Keith

[Greg Smith]

Happened to me due to a bad cps connector. In addition to leading to an occasional no start requiring me to unplug and reconnect the cps wire harness connector it also caused the symptom you describe -- the engine rpm would drop so much on decleration and almost cause the engine to cut out. Check out my cps connector rebuild advice on the thread. Greg

http://www.naxja.org/forum/showthread.php?s=&threadid=8781

[Neil]

Check for vacuume leaks, and/or your MAP. If you have a bad vacuume signal to the MAP the MAP will send a bad signal to the CPU. Pay close attention to the hard plastic lines as they get brittle and crack. If thats not it start cleaning connectors. It could even be the evil C-101.

[pec50]

Hesitation might be something rather simple. Have you tried to run some fuel injector cleaner? Changed your fuel filter recently?

[bgcntry72]

On mine it was a short in the coil wire.

[keith haw]

Thanks for all the replies.. That gives me some more to check when I get back Monday.. Just to clearify it's more like it boggs down then picks back up..

thanks again
Keith

[dusterboy71]

My "88 did the same thing. A can of FI cleaner and a can of heat solved my problem. Also, accelerating stagger could be bad TPS adj. Good luck.

[keith haw]

Well I replaced the O2, coil and cam sensor. Also found the CPS plug flaky. Not sure what the fix was. Seems to run good now but time will tell. Thanks for all the help.
Keith