Rough running engine. (After fresh rebuild)

91BLOWNSC

Registered User
It seems as though my engine does just not idle right. I just had a fresh rebuild about 1500 miles ago. I put solid motor mounts on (don't know if this may be part of the reason), but i just feel it in the car, and I can hear the engine miss, and see the track move. Is this normal for a 3.8L? It seems to be the worst after I have gotten on it some. Also, when i push the brake in and put the shifter in "D" it likes to almost stall. Like it can't hold an idle very good. And the last symptom is when I rev it up in nuetral or park, it takes a long while for the engine rpm and tach to fall back down (well longer than normal). Any ideas?
 
Re: Re: Rough running engine. (After fresh rebuild)

racecougar said:
What does that mean?

-Rod
Whoops my bad, I mean my tach move. Everytime the engine misses, the tach jumps. Does it quite a lot so I guess it misses a ton.
 
Hmmmm

Could be a few things, Have you had the engine attempt to selfcheck for a dead cylinder? The crazy tach could indicate that your having problems with DIS or other ignition parts. The best course of action is test for vaccuum leaks; then from there check compression(or leak down test is best) and plugs. Are you getting a check engine light? Fuel pressure stable? By checking the compression and vaccuum leaks you can determine if the engine is running mechanically fine. If so then have the DIS checked out, also keep an eye on the cam sensor or crank trigger. I believe the crank trigger has to be spaced just right when installed.(along with the cams sensor of course) Does anyone know what will happen if the crank trigger is not spaced right? or comes loose?
 
hmm...

How do I self-check the engine for a dead cylinder. Or did you alreayd explain that? Not sure if I udnerstand how/what that is. I was going to check the fuel pressure, but I am sure it requires a special tool. Is there anyone that can check a DIS module for me? My local autoparts store? I have my friends dis off a 91 SHO, but its a different part #. Will that work on my bird just to see if that fixes anything?
 
I'd be thinking a couple different problems.

#1 - vacuum leak somewhere would account for the slow reduction to idle rpm.

#2 - miss could simply be a bad plug or plug wire. Don't discount looking for that first.

DIS can't be tested off the car anywhere that I know of. Eliminate those first two possibilties though.
 
To check the plugs,plug wires.Just pull one spark plug wire off the coil at a time.
If the motor slows down it is good.
If there is no changes you have a spark plug wire not on ,or bad wire,or bad spark plug.

It's a good idea to put clamps or plactic ties on every vacumm line you can get to.
 
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