Posting for friend, mechanical issues
 

Hello all, my car is a 2013 Subaru BRZ/Scion FRS with 166K miles. Car has not been running well, it sometimes feels like its about to stall out in idle and drops to 500RPM and engine shakes. When I give the car some gas the RPM jumps up and down. I replaced intake manifold gasket, gaskets for fuel injectors all replaced, fuel pump & fuel filter, mass air flow sensor, PCV valve, spark plugs & ignition coils replaced... I don't want to keep replacing parts and guessing at this point. Only code that pops up is for a p0172 for running rich. When I go for a test drive to test it sluggish at acceleration. Any suggestions would be helpful. Thanks everyone!

Only doing it with AC on? Auto or MT?

I don't think mentioned if the AC was on. But it seems to happen if the vehicle is just idling. I'll ask him about manual or auto. I believe is just his O2 sensor being dirty it it could also be his MAF.

This and the torque app are good to have. You can read codes as well as see what the sensors are outputting.

https://www.amazon.com/gp/product/B0...ref_=pd_gw_unk

For sure can be an O2 sensor. There was an idle instability tech bulletin that required a reflash. Being it has been so long and so many miles until the issue I doubt that the TB is it. Reading your first post it says he replaced the MAF.

Your friend's mechanical keyboard broken??

Maybe his “friend” has a burning sensation when he urinates also?

Any power mods?

Recent tune change?

Yes, I would think the first thing he should have looked at was the O2 sensor, as when this doesn't work properly or at all, it can cause quite a few symptoms including the one you he describes.

I would assume, I literally just copied and paste his IM message haha.

Is mostly some rashes on the tip.

My first question to him was that, if he messed around with his tunes because he mentioned having OFT with uncatted headers. Other than that he has an inlet tube and Invidia N1. I read all that and the first thing that popped in my mind was the MAF or O2.

Exactly, he ordered a new O2, so I might go to his house and see what else we can look at. But like I said, is definitely his O2, that's a lot of miles so It would only make sense.

Well the O2 is usually a good check, but more times than not (at least from my personal experience), a fairly beat catalytic converter is the real culprit - in which case the O2 picks up readings that aren't standard and you get the code. So see first if the O2 fixes it and then go from there.

EDIT: Just noticed you mentioned he has un-catted headers.

I believe he's running catless headers. But we'll see.