[bcollier1823]

About a year ago I bought a '98 5.9L and it has ran like a champ. Last January I hit a mailbox. Anyways I finally got around to getting my front bumper and grille replaced, while I was at it I got my car aligned and my front left wheel bearing replaced as well.

Got my car back from the shop and it vibrated since I turned the engine on--really really bad. It feels as if the motor has no oil, but it does and the pressure is good as well, or a broken motor mount. But I did a visual inspection and all the mounts seem to be fine.

I turned it off going down a hill in neutral and it was smooth as glass, but as soon as I turned the beast back on just went to ****. Of course I called the shop all pissed off but they claim nothing they did would affect that, and that it didn't drive that great when I took it there--oh but it did.

Anyways does anybody have any ideas? Would be extremely appreciated!

[JRW7072009]

Have you checked for a vacuum line disconnected somewhere? That can cause a motor to run real rough, if not I can only think to try a tune up (if it has not had one recently) maybe fuel filter. My sister had a bad motor mount on her Saturn recently and it cause her car to run real rough in gear and park but ran pretty smooth in neutral... Hope this help

[baxy]

did they change the crank damper?

[bcollier1823]

Originally Posted by baxy

did they change the crank damper?

All they claim to touch:
Front bumper + Cover
Grille cover
Alignment
Entire front left wheel assembly for bearing

Originally Posted by JRW7072009

Have you checked for a vacuum line disconnected somewhere? That can cause a motor to run real rough, if not I can only think to try a tune up (if it has not had one recently) maybe fuel filter. My sister had a bad motor mount on her Saturn recently and it cause her car to run real rough in gear and park but ran pretty smooth in neutral... Hope this help

It was 'tuned' right before I bought it, and where does the vacuum line run, any idea?

[baxy]

well you need to elimiate one thing at a time
if it vibrates in park all the time start by taking the belt off and seeing if it still vibrates, just run it long enough to check so it wont overheat

[JRW7072009]

I am not super familiar with the ZJs (sorry) but just check all the rubber hoses you can see or touch and make sure there connected or go from one place to another, I cant think of anything that they would have done to make it run bad by the work they did... but you never know they could have dropped a tool and went after it and broke something or anything could have happened ya know. Sorry I cant be more help.

[bcollier1823]

Ran it without the belt on and didn't change anything. I've been driving it though a bit, fresh tank of gas with some injector cleaner. It has gotten considerably better but I don't think it has anything to do with fresh gas.

So it still rides rough but just on startup, and about 1100-1800 rpm. Idle and high rpm are smooth.

Any other ideas?

[bcollier1823]

Well I applied to brake and ran it in drive and reverse. In drive the left side of the engine goes up a few inches and in reverse the right side goes up a few inches.

Would this be the motor mounts?

[indianajeep]

On the driver side fender there is cylindrical valve that has a vacuum hose - check that. Make sure the hoses underneath the throttle body cover are all connected. Look for a loose spark plug wire. Whenever someone wrenches under the hood, it is easy to pull stuff off or knock loose without even realizing it. I had a 03 highlander that the techs used to knock the vacuum hose off every time they checked the air filter - Really annoying. They did not even realize they were doing it - but I would cause the check engine light would come on after a mile or so.

I don't think your motor mounts are bad.