misfire diagnosis help needed
 

01 2.7 manual. Car started stumbling jerking. Car would idle for a few seconds but then die if not revved up
Managed to get home and hooked up VCDS. No codes stored, so I watched for misfires and saw a few. Shoveled some snow and hooked up VCDS again and this time got misfire codes on cyl 1,2,3. Aha!! So I picked up a control module at closest dealer($237 aarrgh) and installed on black connectors for Bank 1, and all was good on initial test run.

Second test run: Check engine light came on, and when I got home, same misfire and bucking as before. Ran VDCS and had codes for misfires and fuel trim, rich running, etc. Cleared codes and watched for misfires in monitoring blocks. Saw random misfires on both Bank 1&2 cylinders but no subsequent codes stored.

Did not see any obvious vacuum leaks(hoses broken off, etc.)

Any suggestions for next steps? Thanks

Boost leak? Misfires coupled with running rich... Check the TB hose.

Update. I checked the hoses and all appear good. I found just now that the problem does not show up until the engine was warmed up. After reading the recent all road thread about similar symptoms and a MAF problem, I wiggled the MAF connector and moving the MAF caused the engine to stutter. I then tried unplugging the MAF and the engine smoothed right out.

So looks like time for a new Hitachi MAF.

Thats odd that it would only cause issues on one bank no ?

You could try that "MAF" cleaner spray specifically sold for this purpose.. check Autozone etc.; Not that it worked for me, but some say that it did! Wouldn't hurt..

I think I might have had 2 problems. Bad bank 1 ignition output module that triggered the across the board Bank 1 codes. After that was fixed, the random misfires were on both banks, maybe a few more on bank 1. New MAF is in now the car and everything is fine. Put the new sensor on in the dealer's parking lot, so I wouldn't drive back home with the sensor unplugged. Felt like a real swamp yankee doing work on my car in the lot!

Bought the MAF sensor from Carson "the parts guy," who has moved to NJ and is working at DCH in Millburn NJ. Finally a dealer that stocks C5 parts. Logging on to millburnaudiparts.com gets a great discount, which Carson gave me on the MAF.

We had a good discussion about snow tires. He has the Generals and I bought the Firestones with studs. He loves his Generals and my Firestones are a bit squishy, but still good in snow and the studs are great on ice.