I bought a 2002 Jetta turbo a few months back, and one of the coil over plug packs went south (P303). My mechanic checked out the crank sensor among other things, and said one of the new iridium plugs was fouled. So he replaced all four at $10 a piece. I also bought four new coil overs, replaced the originals, and the car ran fine for a month. Yesterday one cylinder was misfiring, so I swapped them around and the car ran fine again. ODB displayed a P301. So without replacing any coil overs, the car ran fine for 24 hours and now we're back to a misfire.I don't have an ODB and I've been going to Advance to get the codes. I suspect it's another coil over.
What in the world is causing this intermittant misfiring?
I would back up to basics. Start with a compression test. Look for vacuum leaks around the intake.
July, 7, 2012 AT 4:40 AM
Also check with the dealer for updated versions of the coil. They had a recall on some of the coil overs. Recalls are good and do not expire regardless of miles and usually free because of safety issues.