Recently did a gas engine swap on an '08 Gen 2. Initially had horrible misfires after swap. Cleaned throttle body and put fresh gas in it and no problems for the last month. Until one of the top seals on one of the recently replaced injectors failed and caused a small fuel leak. Today I fixed the leak and now have multiple misfires again as well as a trouble code for the mass air flow sensor and lean bank one too.. I have another '08 that I was able to swap out a MAF from and concluded that is NOT the problem. Any help is very much appreciated.
Could be unmetered air (air leaking in somewhere downstream of the airflow sensor). A smoke test might help find the leak. What are the codes you have exactly?
Got codes PO300, PO301,P0302, PO303, P0171. Problem was resolved by removing #4 injector and cleaning where the bottom seal meets the cylinder head. Thank you.
Got codes PO300, PO301, P0302, PO303, P0171. I just replaced all the ignition coils and spark plugs also before this happened.
One thing I noticed on the bottom of the airbox where it meets the throttle body, on the clamp that seals it up there is a notch in the clamp and a small piece on the rubber airbox connection that fits into that notch. If you don't have that lined up correctly it won't seal and you may get a MAF trouble code and a misfire from it due to the sensor sucking to much air and essentially a vacuum leak.
If it happened right after the fuel injector repair, there may still be air in the fuel injector rail, causing a lean initial misfiring fit. This happened to me as well just a few days ago, and it took some thinking to figure this out. That would make the most sense. I depressurized the fuel system first by pulling two fuses related to the engine and fuel system before starting the work. So I'm thinking, that could well be your problem. Priming the fuel pump by turning the car on accessory mode a few times can repressurize it. Also check and make sure the fuel injectors are properly seated, that the fuel rail bolts are properly and evenly tightened, not too tight or too loose. Make sure O-rings are not rolled or pinched. Lubricate the O-rings first before insertion. It can be lubricated with things like a small amount of clean engine oil or gasoline. It's definitely a good idea to diagnose the real culprit (s) of your car problems before trying replacing parts randomly just to see if it solves the problem. It will save you money and hassle. Or, if you still can't figure out what's going on, then, I'd suggest taking it to a mechanic. I'd suggest you do some research on these matters.
