MAF is clean. E gas reset done. RKAT all normal. Smoke test revealed no vac leak. Plugs are new. Fuel filter and air filter are new. No codes stored. CEL is clear. Scanner used to monitor engine performance during test drive revealed all readings are normal and as expected. All parameters, settings, and indications are within spec. No problems found. Rough idle and vibration remain. I wish there were an idle screw so I could adjust the idle RPM from 750 to 800 because a slight increase in RPM smoothes it out. Ideas exhausted. To live with it or to Carmax? That is the question.

 

Sorry if I missed this somewhere, I'm pretty much out of ideas here without physically seeing the car, but cut open the engine oil filter and inspect for debris. I have noticed on a few cars where I installed the LN Engineering IMS Solution that the "normal" roughness vanished after the install. It could be a problem with the IMS bearing.

 

What is the IMS bearing? I just changed the oil. Can the cut-open wait until the next oil change and is the bearing replacement a must do to avoid a catastrophe? And how big a $ deal is it? Sorry, I'm a golfer and not a mechanic. Everything you guys tell me is like gold to me. If it means anything, the guy that changed the oil commented that the old oil was like new and it was 15k old.

 

That's good the oil looked like new. No worries. One of the weaknesses identified in recent years by Porsche has been the intermediate shaft bearing (IMS bearing), which supports the intermediate shaft on the flywheel end of the motor. In theory, the area where Porsche designed the bearing to sit is supposed to be dry. However, after years of use within the engine, it would appear that oil and contaminants from the engine seep past the bearing seal, wash out the original lubricant, and become trapped inside. The result is that the bearing now operates in a less-than-ideal environment and begins to wear prematurely. When the bearing wears out, the timing chains on the engine may disengage, and the engine will quickly self-destruct. When the bearing does begin to deteriorate, foreign object debris from the bearing circulates throughout the engine, causing damage to other areas in the engine. All of this information, including replacements that should be done can be found at our IMS tech article here. Let me know if you have anymore questions.

 

Great information and thank you. I will have the oil changed at 5k and have the filter examined. If no metal is found, I should be able to assume that all is ok. If debris is present, I will have the bearing changed. I suppose changing oil at 5k on an 11 year old car that has 71k on it is better practice than every 5k. If debris ever shows up we go after this bearing.

 

My pleasure. I'd also check and see if/when it was replaced. Recommended interval for the bearing to be changed is 30,000-45,000 miles. (Typically anytime you do a clutch replacement). If it hasn't been done, I'd recommend doing it. This video here is also very insightful about the IMS bearing.

 

I don't think the car was maintained at all by the previous owner. I've already spent $20k on it bringing it back to good life and am not sure it's worth thousands more to do the bearing. But, I will consider it. I appreciate your help very much.

 

My pleasure. Good luck with everything and let me know if you need any further assistance.

 

would it be engine mount?

 

The Coils could be another source. They tend to degrade gradually and you may not be getting the optimal spark as a result. They may be degraded but not to the point of throwing a code. Also have you checked the transmission mount? I dont know where you are having it serviced but I had a reputable independent do my Clutch/IMS/RMS for $2500.