I have a K & N air flow system on my 2003 911. Every few years my MAF goes out because of the oil from the filter. Last month I replaced the MAF and the car was running fine, all of a sudden it started to run rough off the bottem. It seems to get worst as the is warming up. When I unplug the MAF the car runs good again. My engine light is not on, usually when the MAF goes bad it goes on. Is there anything else that can cause this issue that works with the MAF? All help is welcomed.

 

I hate to tell you this, but the solution is to pull the k&n system off. Those systems are notorious for ruining maf sensors, and you will constantly have a CEL light. They were big sellers due to their hp gains in the mid range, but hit bottom once everyone started have maf issues.

 

Thanks for your suggestion but I would like to try to find out the cause of the current problem. I know that the K & N causes the MAF to fail every few years but now it seems to be something else.