P1126 and low rpm hesitation - all troubleshooting listed- Help greatly appreciated!

[porschefan76]

Originally Posted by blue62

My understanding of unplugging the MAF sensor is that the DME reverts to a default fuel map in open loop mode so there is no closed loop type fuel correction.
Also this default fuel map is on the rich side so if you have a vacuum leak and you unplug the MAF the car tends to run very well. Not to say your issue is not MAF related could very well be. Will be interesting to hear the outcome after you install the new MAF. I hope you ordered a Bosch MAF these cars don't seem to do well on after market MAF sensors.
Also if your running a K&N filter that is the oil type they destroy MAF sensors

Hey blue62! Yes, I agree, although I'm not sure it's running rich, as the RKAT is 0.0 and the FRA .99 and STFT look like they're operating properly going +/- 5% throughout the test drive. I'm really hoping it's the MAF as the negative RKAT values (rich at idle) just don't make sense and I have taken each vacuum hose off of the reservoir and tested with my hand pump and they've passed. I've still yet to fully test the EVAP system (vacuum etc) but the Evap Valve under the bank 2 air intake appears to be functioning properly. Beyond that though, no testing has been completed on fuel canister/hoses etc. I'll post as soon as I get the new MAF in and a test drive/data.

EDIT: Forgot to mention, yes, it's the Bosch replacement MAF and the K&N filter is in a landfill somewhere these days. Replaced with OEM air filter.

[porschefan76]

Ok, I think I'm going to call this the end for now. I installed the new MAF sensor and took a test drive. Wow, what a difference, driving much better than without the MAF. I did not reset the codes (P0102 and P0112, both for MAF) as I was thinking they'll reset themselves after a couple of drive cycles like other codes. Is this true for the MAF codes or should I just reset them?

I took some data samples as well. Bank 1 RKAT is -0.17 & FRA is 1.00. Bank 2 RKAT is -0.20 and FRA is also 1.00. O2 sensors all looked like they were doing their thing! Very excited, but I only did roughly 20 mile test drive tonight because:



Out of the frying pan and into the fire HAHA It doesn't look like it's been leaking for long, and it is a very small leak. I got my borescope out and I think it's a crack in the tank at the usual spot underneath:



Sorry about the poor focus but it's essentially a point-and-shoot 1080p borescope. Tank, cap & sending unit are ordered and should be arriving mid-week, so I guess that's the next project for now. Once that's replaced, I'll put some miles on the car with the new MAF and verify I do not get the codes back. I'll post back after a few hundred miles. Thanks all for all of the help!