Question on Motor Mounts and Hesitation

[Da Coop]

My CHECK ENGINE SOON light went on Tuesday. Wednesday I took to shop. They also got code 301 and 325 errors. My car has been doing this interesting bucking thing for the past week, and sometimes when you are driving it will seem to hesitate, as if the engine isn't getting gas for a second, then it will pick up where it left off.

Very strange.

I got a tune up which helped with the power and the code light went out, but it still does the hesitation/buck thing. Not all the time, but I did notice it today.

It also is making this rubbery scraping sound under the hood/front end somewhere. No one at the dealership can replicate the problem so as far as they are concerned it doesn't exist. I am wondering if perhaps there is a motor mount broken or if I need to have suspension bushings replaced.

Anyone have thoughts on what issues might be here? How would I check to see if I need motor mount work or if the bushings should be replaced or if there is something MORE serious going on with the suspension?

P.S. this car was an east coast vehicle and it was discovered to have rust underneath. I got it rust treated but am now wondering if these problems may be related to the corrosion.

[Venger10]

Hesitation is usually related to the TPS(throttle position sensor)It may be out of adjustment or bad , it won't always show up on a diagnostic

[lordrashmi]

I got the same codes you did so I think I can help you out.

P0325 (Knock Sensor)
P0301 (Cyl 1 Misfire)

301 is the important code because when you get an engine misfire code, you also can get a "ghost reading" of 325. And when your engine is misfiring, the car runs like total crap. In my case, the problem was a faulty coilpack. I had tried to diagnose it myself, but I was looking at the wrong cylinder (Damn the information from the internet). Cylinder #1 is the rear, passenger side cylinder. If you have a multimeter you can take the coil off and check its connections to see if it is faulty (If you want I will scan the page from the manual I have when you get home). Or you could just replace it. I believe the part is about $70-$100 bucks. I just picked my car up yesterday and parts + labor was $170.

Hope this helps. Let me know if you want that manual.