1997 Saturn SL1 Engine shakes the car


#1

The car shakes slightly when the car is idling. I can see the reflection of the headlights shaking up and down when in drive but at a stop. It doesn’t seem to be as bad while it’s in park. While the car is moving, the shaking isn’t noticeable. But is when the car isn’t moving. A friend guessed that it might need a tune up. I had the tuneup done and it’s still doing it. Another friend said it seems like it might be a broken motor mount.

What is your opinion?


#2

This one takes a “hands on” analysis, its difficult to answer over the internet. The first thing that needs to be determined is if the shaking is due to an engine “mis”, that is a misfire. If the engine isn’t misfiring, then it could be an engine mount. A defective engine mount usually causes other problems as well, like pulling to one side when accelerating.

If the engine is running rough due to one cylinder not contributing its fair share of power, then there could be a number of reasons. Do you have a check engine light? If so, go to AutoZone or other car parts store that pulls coded for free and get the codes read. Is the idle high? over 950 rpm? If it is and you don’t have a check engine light, then let it idle for two minutes and you will get one. If this is the case, you should get a code P0507 and the cause is a bad intake manifold gasket, a common problem with the SL1 engine. BTW, the code will tell you its the IAC, but its not.

If the idle is normal, around 750, and the engine is rough and you have no check engine light, then listen to the exhaust. If you hear a regular “pop” sound at the muffler, then you probably have a burnt exhaust valve. Then you will have to decide whether you want to spend the big bux to fix it or just live with it. It won’t cost you more if you wait, other than maybe 1 or 2 mpg.

I have this problem with my 02 Saturn at 160k miles. I’ve been through the intake gasket problem, but this one I’ll just live with for a while.


#3

The last Saturn I saw with this problem had the plug wires put on wrong. I took one look of a picture of the engine and solved the problem. Hey! These wires don’t look like the picture in your manual!


#4

1)if the shaking is due to an engine “mis”
Would that be corrected by a tune-up?

2)defective engine mount usually causes other problems as well, like pulling to one side when accelerating
It doesn’t pull when I accelerate.

3)If the idle is normal, around 750, and the engine is rough and you have no check engine light, then listen to the exhaust. If you hear a regular “pop” sound at the muffler
The idle was real high until the tune-up. Now it seems just right.
There is no check engine light on - I’ll have to check and make sure it isn’t disabled or burnt out. I’ll post back after I check it.
I don’t hear any kind of popping sound coming from the muffler. Sounds real good.

I checked a Haynes book for the car and it seems there are only two engine mount locations. A mechanic told me there are more. The one on top seems ok but I don’t know if it’s something that can be checked visually. The one on the bottom I don’t think I can check without jacking up the car.

Thanks so much for the info and thanks in advance for any further assistance.


#5

You can check the check engine light by turning the ignition to the on or run position but not starting it. If the light comes on, its ok. Now I’m concerned that your mechanic may have adjusted the throttle stop screw and that will bypass the computer. One check for the intake manifold gasket is to spray some wd40 or carburetor (or fuel injector) cleaner around the intake manifold gasket, especially around the #1 cylinder, more specifically around the forward lower corner of the #1 cylinder. If the idle suddenly smooths out or changes in any way, the gasket is leaking.


#6

One more thing, a defective fuel injector could also cause a rough idle. A tune up is usually only spark plugs these days. A mis can be due to other things.


#7

If the sparkplug wires are on wrong, its going to shake a little more than “slightly”.