Originally Posted by CJ_Boxster (Post 420360)

if the pop sounded like a gun shot behind you, your issue is a check valve located on top of the engine, mounted underneath the intake plenum on the drivers side of the engine, it has a plastic hard pipe that leads to the front of the engine bay and runs down to the under carriage along side other similar style plastic hoses... if your lucky You can test it but having the engine running, and engine cover off, locate the valve and give it a hard smack with the handle end of a screw driver, sometimes itll unstick and cel will go away but the cel will come back usually once the ecu tries to trigger that valve into another position, causing it to get stuck once again.

had the same thing happen to me (1 gun shot sound) and 986 was really under powered and I kept going back to maf and aos replacements till i did some research and made the proper fix.

Im talking about part 14 in the image below.
http://farm5.staticflickr.com/4110/5...eb24643f_z.jpg