P1126 and low rpm hesitation - all troubleshooting listed- Help greatly appreciated! - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Gilles · 02-25-2021, 02:41 PM

just curious, could a Dry fuel injector Seal could cause a vacuum leak..?
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porschefan76 · 02-25-2021, 03:48 PM

Quote:

Originally Posted by Gilles

just curious, could a Dry fuel injector Seal could cause a vacuum leak..?
.

Hi Gilles. Having just replaced all of my fuel injectors, on the fuel rail side, I think you'd have a fuel leak (pressurized fuel rail). On the intake manifold side, I suppose you would have an vacuum leak, yes.

If you have to replace your injectors or o-rings, I used a small amount of the recommended white lithium grease on all of the o-rings and it really made everything go back together nicely and prevents the o-rings from twisting upon insertion. Thanks!

Gilles · 02-25-2021, 05:13 PM

Thanks for the tip!

porschefan76 · 02-26-2021, 06:16 AM

Quote:

Originally Posted by Gilles

Thanks for the tip!

No problem! Good luck! Bank 1 injectors are worlds easier to replace than Bank 2 due to tight working quarters with respect to the fuel return line nut.

porschefan76 · 02-26-2021, 08:38 AM

Quick update - all information I am able to find states 17 to 23 inches of HG (8.35 psi to 11.3 psi) for proper intake vacuum. This contradicts the Porsche information I had (5.8psi to 8.7 psi) but I imagine being within a +/- 1 psi might be acceptable.

Only posting this because if I have proper intake vacuum, it seems less likely I have a vacuum leak, so I'm hoping those numbers jump out. If not, I think this leaves me with the EVAP system (electric valve stuck open? but no CEL or code?) and then it's on to mechanical problems with the engine (timing, valve seat issues, compression).

Thanks for your time!

porschefan76 · 03-10-2021, 02:18 PM

Hello all, time for another frustrating update.

So, I replaced the spark plug tubes. This made no change (well, no more oil on the valve covers) but after two test drives, no P1126, fuel economy seems to have returned but the car just feels "slow" overall and the induction noise is muted. It just doesn't sound or feel 100%. Additionally, I found two threads that mentioned the contacts within the electronic throttle control on the throttle body can be misaligned and for someone, this was causing their 986 to run rich at idle. I opened it up, cleaned up the electrical contacts, but overall it looked healthy and clean. Simultaneously, I also purchased a new electronic change-over valve for the resonator flap. I got a little encouraged when I found the rubber vacuum boot attached to the old change-over valve was stiff and looked tired. I replaced it with new rubber vacuum hose. All of this resulted in no change to engine operation and after about 120 miles of test drives, P1126 returned and this time with a P0107. I had this code briefly a few months back, but I didn't have my battery tender at the time and the car had been sitting, so I assumed it was related to low voltage, reset the code and continued troubleshooting. This is the first time it has returned.

According to the Bentley manual, P0107 isn't listed for DME 7.2 but Durametric reported it with the same verbiage as listed that in the Bentley manual for DME 5.2.2.

I've read a couple of posts on P0107 and the MAP sensor is internal to the DME, so it seems the advice goes one of three ways:
a. Reset code and see
b. A bad MAF might be the culprit
c. Replace the DME

Anyone have any experience with P0107 and P1126? My MAF data makes it appear the MAF is functioning properly. Is it possible it's an intermittent failure with the MAF? Any help or ideas will be much appreciated! Thanks.