[shushikiary]

So I recently install a second inline fuel pump from SteveAZ, it seems to be working great and I had no issues for about 3 days until I drove up to about 9000 feet ASL in aspen colorado. There I was in town but they dont have E85 near by so I took a 5 gallon gas can with me. The can had E85 in it from a little over a month ago and measured in at 70% ethanol.

After I added the E85 from the can I starting getting a stumbling issue where at partial throttle I would lose all power for a fraction of a second and then it would come right back. Once I got back down from high altitude the problem seemed to go away for a little while and then came back. I filled up with about 1/2 a tank of E35 (what I normally run) when I got back down to denver, however I havent gone through an entire tank of gas yet sense I put that E85 from the can in.

Anyways, frustrated I pulled all the spark plugs and found cylinder 6's plug was bent, the overhang was literally bent to the side... Not sure what was going on there, but I bent it back into place and gaped it properly (note these are NGK's). Nothing wrong with any of the other cylinders.

I also pulled the LPFP just to take a look and did find one of the power lines not completely plugged in so I pushed it all the way in and then zip tied both power lines for the new in series pump in place so they couldnt move.

I then drove the car again, and found that it was still stumbling.... so I decided to take some data logs with my COBB. I have the VRSF stepped 5", VRSF DP's, BMS DCI, running E30 map.

Here is the data log that appears to show what is going on:

http://www.datazap.me/u/shushikiary/...log=0&data=1-7


It appears to me that the AFR is going really high for both banks when the car "stumbles" Given the length of time that the AFR goes high it seems like I either lost all fuel or the fuel would simply not burn. The HPFP pressure is great, so is the LPFP pressure, so unless I couldnt flow fuel for some reason yet somehow still maintained proper pressure (which doenst make sense, the pressure should drop if I wasnt getting enough fuel I would think) the only conclusion I can draw is that some of the gas from the E85 gas can was bad.

I should note that when I used the E85 can a month ago it was in buena vista and it had rained just before I used it, I only used 1 gallon out of it, so there was about 1/4 of the jug of open head space with possibly high humidity air in the can for a month, so I'm seriously wondering if perhaps the E85 picked up some moisture out of the air and that is what is causing the problem.

The car does throw codes sometimes when it happens, but its almost always been "fuel pump plausibility" the silly P2AAF code, I did get one code that was "cylinder 6 miss fire with cut-off" P2B3A.

So I just want to see if anyone else has any idea's as to what might be going on.

[SteveAZ]

2aaf is normal for running when running E85, upgraded fuel pumps, or making a lot of power. It's your DME recognizing that the fuel system is pulling more current than what it normally would with a stock pump and regular fuel. It's a shadow code and doesn't cause any issues.

More concerning to me isn't your AFRs going high, but them bottoming out when you let off the gas. As you can see here. That'll definitely make your car stumble and sputter.



This can be caused by your trims bottoming out and the DME is no longer able to pull fuel to achieve the target AFR's.

You'd need to log both STFT's and LTFT's to see that.

I'd run that fuel out and if your still having issues log your trims. Your adaptions may need reset.

Your fuel pumps look fine...but that is at low rpms. The LPFP is around 81. For some cars that's normal and for others that's an indication of the DME running it at 100% duty cycle because the trims are OOC.

[shushikiary]

Thanks!

I reset the adaptations when I was in aspen thinking that might be the problem, but I'll check my fuel trims to see if they are maxing out.

I should fully run through that tank of gas by thursday or friday. Here's hoping it was just some bad gas.

[SteveAZ]

If you reset adaptions with the Cobb...that is completely worthless.

If needed, it should be done with a BT cable or through INPA.

[shushikiary]

Oh, yea I did it through Cobb... Sadly I was hoping that would be good enough.


Well if it continues I'll have to buy a cable and get INPA installed on a lap top.

I searched on how to do that in INPA and found post #2 here: http://www.e90post.com/forums/showthread.php?t=928085

Which adaptations should I reset should I need to end up doing that?

This post may have answered the question as well but I'd like to make sure: http://www.e90post.com/forums/showthread.php?t=984889

[shushikiary]

Figures I'd make this thread and then the car would run beautifully, so far the stumbling is gone (I just ran through a full tank of what would have been the previous gas).

Fixing the 6th cyl spark plug also made an interesting vibration I had if you floored it in 6th great between 2-3K rpm go away, and the car used to feel like it took off with a jump after 3.5k RPM when flooring it but now that vibration is gone and the car has a very smooth power band across the board.

I also kept an eye on my STFT and LTFT's while driving around, my STFT's spiked at -31% and my LTFT got down to about -22%, on the upper side LTFT's spiked around 26% when under WOT, however the STFT pegged at 34.2% in 4th or greater gear above 3k RPM, though the AFR was still around 12.1 around 3k RPM, and still got into the high 11's at red line 3rd gear with STFT's pegged. I guess that's good news there, but I think I should reset the adaptations given what I'm seeing.

So I've ordered a cable and will reset the adaptations per the 2nd link I posed in the post above once it arrives.

Update: It stumbled again today, looked at the COBB while it was doing it and sure enough the STFT was pegged at -33.8 while it was stumbling, strangely the LTFT was at 10.9 at that time, and the LPFP was at about 83 PSI. I think you're right on par, the new pump is giving me more fuel then it is expecting and thus the adaptives need to be reset.
Here is another data log showing the vent, sure enough the AFR on the stumble goes to 11 or so... seems like the LTFT need some adjustment in this conition, so I'll reset as soon as the cable comes in: http://www.datazap.me/u/shushikiary/...6-7-8-11-12-13