jeebus31

Howdy. I am in need of some diagnostic help.

P2188 and P2190 are coming up on my 997.1TT (rich at idle banks 1 and 2). Came up one week apart, but these codes have been intermittent for a while. I would go months between codes but they are more frequent now so it's time to really dig in. Checked both MAFs at idle and the voltage was right at 1.3V for both units, which I believe is normal. I cleared the codes 7 days ago, drove it about 20 miles on Sunday/a few light pulls, and then parked until Thursday. After driving it to and from work on Thursday the trims were:

STFT1 0%
STFT2 0.8%
LTFT1 6.3%
LTFT2 6.3%

I drove it around on Saturday afternoon after some minor suspension tweaks, got a full tank of gas but didn't do any real hard pulls, and the fuel trims were:

STFT1 0%
STFT2 -0.8%
LTFT1 8.6%
LTFT2 9.4%

I washed the car, then took it to dinner and back Saturday night and the trims were now:

STFT1 0.8%
STFT2 0%
LTFT1 10.2%
LTFT2 10.9%

Today, I took the car out for some photos and it did spend a fair amount of time idling, and I was starting it up multiple times and moving it short distances, etc. I did get in a number of good pulls and took the long way back home, though.

STFT1 -15.6%
STFT2 -13.3%
LTFT1 14.1%
LTFT2 14.1%

As I was staring at those numbers on my OBD2 reader as the car was idling in my garage, the CEL popped up for P2188 and P2190.

I don't believe I have an air leak but my smoke machine leaves a lot to be desired. I think the MAFs are functioning normally per the voltage reading at idle. I was wondering if it's possible for this to be a failing fuel pump? Is there a good way to test the FP? For what its worth, the car acts normally, I have no issues at start up, no hesitation and it pulls hard throughout the rev range. Thanks for any and all input!

964hans

Some info concerning 2188 and 2190 (see attachment)
Regards, Hans

jeebus31

Thank you, Hans. I appreciate the literature. I think I read part of that document over on a Renntech thread but it is helpful to have the PDF.

I am going to replace the fuel pressure regulator... the hose to the FPR is attached but it's a 30 dollar part from Bosch and I've read that it may be responsible for rich idle states. Perhaps a leaky injector?

Kevin

Post your mods

Connect a fuel gauge at the "tap" you should be seeing 3.8 bars or 55 psi at idle. Also measure your alternator/battery voltage

jeebus31

Fabspeed intake
FVD exhaust
FVD tune

So I replaced the MAFs - they were original and the PO was running a BMC filter at some point. The fuel trims have stayed normal for the past week and about ~100 miles of driving since I did the replacement. Maybe it was just old MAFs.

We did a smoke test today and there were no leaks. I am going to do a boost leak test once I get all the parts in. I finally got the right M10 adapter for the schrader valve so I'll be able to do a fuel pressure test now.

jaykkub

How are things running? I’m getting the same CELs as you’ve mentioned. Previously I was getting P0420 and P0430 (always together). I’m hoping to be rid of this issue once and for all...hopefully soon.

jeebus31

No issues so far. I have been checking the fuel trims after every drive and they are stable.

lliejk

I wonder if the MAF's just needed to be cleaned? If they are still around, AND if you have the time, it might be interesting to find out, especially since the values seemed right on.

Ed

jeebus31

Cleaned them twice in a span of a couple months and the errors codes kept popping up. Didn't want to drop $400 on new ones without being totally sure... but it seems to have done the trick (fingers crossed).

jaykkub

I recently cleaned my MAFs as well (in the last three weeks), but these four CELs still remain.