2005 Cadillac Deville Motor Shake

[Cwbysfn84]

Hello! First time posting anything like this anywhere. Been having trouble with my 2005 Cadillac Deville.

It’s always had a small shimmy ever since I got it but it’s gotten progressively worse while trying to diagnose.

Now the service engine soon light is flashing and the shake is getting worse. It’s almost how I imagine low fuel or air flow would act. The shaking of the motor seems to stop when I accelerate and at higher speeds is almost unnoticeable. Motor mount is fine, tan codes and it does say there’s a misfire detected but it doesn’t show a code for which one. Please, any suggestions? Thank you all for your time. 

[rockfangd]

If you have the 2 coil pack units, one for each bank I bet one or both is failing. I changed quite a few of those.

One was silver, one was black. But both were the same otherwise. You need a actual scanner to see which cylinder(s) are misfiring.

I typically see cracks, evidence of arcing. A big one is oil in the spark plug wells as well. Cam cover seals fail around spark plug holes and seep oil into spark plug well.

If both coil pack units are original it would not be a bad idea to replace both to prevent future failure. May only be available in one color though.

Welcome to CaddyInfo. You have come to a great forum

[Cwbysfn84]

18 hours ago, rockfangd said:

If you have the 2 coil pack units, one for each bank I bet one or both is failing. I changed quite a few of those.

One was silver, one was black. But both were the same otherwise. You need a actual scanner to see which cylinder(s) are misfiring.

I typically see cracks, evidence of arcing. A big one is oil in the spark plug wells as well. Cam cover seals fail around spark plug holes and seep oil into spark plug well.

If both coil pack units are original it would not be a bad idea to replace both to prevent future failure. May only be available in one color though.

Welcome to CaddyInfo. You have come to a great forum

Thank you!!!!! I checked and all my coil packs are individual. I don’t have the banks. Also, when I’m traveling on the freeway and going down a long hill without pressing on the accelerator the service engine soon flashing just stays steady. I will check each coil pack and look for damage. 

[rockfangd]

Ok so you have early generation Coil Over Plugs. I like these better, but are still prone to failure. The good thing is they are cheap and easy to replace. Once you find a way to pull specific codes you will know which cylinder(s) are missing. Flashing light means miss is currently occurring. Solid is a hard code from the soft codes. They will usually misfire the most under load, but can at idle as well. Have the spark plugs ever been replaced?

Also same issue with the cam cover seals leaking oil.