Ever get this sorted out? I am having the same issue with my car. Lumpy idle, misfires on cylinder 4 but I have no CELs.

 

I think it is in my tune along with having tighter gapped plugs. Everyone always says it is that same cylinder when they have misfire issues so I don't know if the computer is mistaken or what the issue is.

 

stock tune here, stock plugs/gap and 997tt coils that were just replaced.

does your car still have this issue?

 

cylinder 4 is the common one for phantom misfire

 

I swapped the tune to an emissions cheater tune Todd sold to me and it misfires much less with that tune which is what makes me think it is related to tuning. So basically yes I still have the misfire.

For reference.

 

@Bernard IV

I know you have a built motor..are you running the stock FPR or a 5 bar? Don't recall.

I was going to test my fuel pressure today but I am in the process of flushing the coolant and changing a radiator so it will have to wait. There is a guy on youtube who had a similar issue with cylinder 3 & 6 and it wound up being the FPR

 

I might try to change that then. I know the 997 Turbo FPR has a larger return flow hole or whatever so it is a little upgrade. I am running the 3.8 FPR with 60lb injectors. The original motor I blew up also had the same misfire.

Edit: I just ordered one from Protomotive so I'll see if it fixes anything.

 

Pls keep updated! I am going to try and test it this week when I get it back together.

 

Will do. It's kind of a pain to get in there but I have a few things I need to get cleaned up with the engine anyways.

 

I just changed my exhaust and I can hear a slight miss at idle too. Very minor, almost wouldn't notice it. I'm guessing it's plugs, mine are very old. Gonna change them and coils.

 

Do you have the durametric tool or an obd2 scanner with enhanced features for data logging?

Could you identify what cylinder is misfiring? I can hear the misfires on mine and it counts on the durametric in real time.

 

yes, but I'm just listening at this point. My plugs are old and overdue. Car runs fine otherwise. I wouldn't worry.

 

I went out to the garage 3 times today trying to get motivated to swap out the FPR. I really hate taking out that air pump, kills me.

 

I hear you. If you're ever out near NYC in the next 6 months, dinner/drinks on me if it motivates you anymore! I've been meaning to check my fuel pressure and start working on my coilover install but my other cars need stuff done.

 

I installed the Protomotive 3.8 FPR. I am still getting a slight misfire using the 2013 tune. The FPR may have reduced the frequency but I will need to test it more to confirm. I do believe it is in my tune or something to do with having tighter gapped plugs. Occasionally it used to have quite a fit of misfires at idle but that was pretty rare so I'll see if that still happens. Not fun to change but at least this FPR has more return flow so it is a slight upgrade.