[Etlafond]

Hi guys.

I'm having what feels (to me) like throttle closure / stutters during a pull.

I had a similar issue a while ago where it would throw lean codes, but that was fixed after changing my o2 sensor, during pulls my hpfp would be way below target, this is no longer the case.

Here are two logs, in log 1, the car stuttered quite hard and the car backfired, at around 5800rpm.

Log 1: https://www.bootmod3.net/log?id=6317...0b43f4c1a864df
Log 2: https://www.bootmod3.net/log?id=6317...729b77b7fcddda

after those two pulls I got a code

104302 Absolute pressure sensor, intake manifold plausibility caster pressure too low.

Would you guys have an idea what could be my issue?

(map sensor has been cleaned and also tested another one to rule this out, same behaviour)

Thanks in advance!

[thejeremyman9]

Did you shift or did the car? According to the log the car shifted from 3-4 right at 5800 rpm and then again from 4-5 shortly after, all the while you were WOT, the throttle was open 100%, and you were still at full boost. The throttle didnt close until you let off the pedal.

Also, your HPFP is still crashing, dropping up to 1800 psi below target, which is the main "issue" that pops out. Your LTFTs seem abnormally high, but you didnt list mods, so not clear if you have an intake. Your STFTs are flat for a bit of the pull but eventually pull up to 16% fuel out briefly.

Timing looks a little strange the way it goes up and down but all cylinders are even. The "stutter" you feel is probably from a combination of the timing drops and the HPFP dip.

https://f30.bimmerpost.com/forums/sh....php?t=1732327

EDIT: above is referred to log 1, didnt look in detail at log 2, but HPFP appears to also crash.

[lens]

Originally Posted by Etlafond

Hi guys.

I'm having what feels (to me) like throttle closure / stutters during a pull.

I had a similar issue a while ago where it would throw lean codes, but that was fixed after changing my o2 sensor, during pulls my hpfp would be way below target, this is no longer the case.

Here are two logs, in log 1, the car stuttered quite hard and the car backfired, at around 5800rpm.

Log 1: https://www.bootmod3.net/log?id=6317...0b43f4c1a864df
Log 2: https://www.bootmod3.net/log?id=6317...729b77b7fcddda

after those two pulls I got a code

104302 Absolute pressure sensor, intake manifold plausibility caster pressure too low.

Would you guys have an idea what could be my issue?

(map sensor has been cleaned and also tested another one to rule this out, same behaviour)

Thanks in advance!

What thejeremyman9 essentially said.

Your AFR's go super rich up top, and the HPFP can't handle the load, which is why it crashed.

I'm leaning toward a failing HPFP.

[Etlafond]

Apologies for the lack of info, here are my mods.

Catless DP
FMIC
cts turbo charge pipe
3.5 bar tmap sensor
BM3 stage 2 91oct (non agg)


So a few months back, I was getting a similar behaviour (stuttering) through the rev range with HPFP crash in the logs, EVERY time i was doing a WOT pull (part throttle - 75% ish throttle pulls hard without stuttering), I would get a code "engine mixture too lean" you could see, just like now, in the logs, the car going rich and then hpfp crashing and throwing the mixture too lean code.

while trying to troubleshoot, I changed my O2 sensor (ptf were saying the "slow" reaction of the oxygen sensor was why my car was acting this way.

Once I changed the o2, I did some pulls, no more stuttering, logs looked clean (no more hpfp crash)

a few months later, haven't drove the car much due to wfh, when I went to do a WOT pull the stuttering was back, I've seen done many pulls and I NEVER get the engine mixture too lean code.. strange since the behaviour (to me) seems the same, but I do not get the same code I used to get (I was getting the engine mixture too lean for almost a year before changing the o2)

The only code that pops up once in a while is "104302 Absolute pressure sensor, intake manifold plausibility caster pressure too low."


when I was initially troubleshooting this with PTF, they had me log pulls with the MAF unplugged, while the car would feel a tad bit more "smooth" I would still get HPFP crash.

So today I decided to try it again, here are two quick pulls (they're not full on pulls due to way roads are around where I live, but still we can see a gear till almost redline.

In the two pulls , there are no HPFP crash, and the car felt solid and pulled hard.

https://www.bootmod3.net/log?id=631b...90c69a0b811b41
https://www.bootmod3.net/log?id=631b...90c69d7d3538f3


I'm getting confused, if really it's just the hpfp failing, I'd have no issues replacing it, I have a feeling the HPFP is not the issue (I may be wrong) cause in some logs you can see it crashing, and in other it holds it's target till redline

Let me know if you see anything weird in the logs or are they looking good? I'll keep running mafless for some time and see if I get stuttering while WOT.

Thanks in advance!

Etienne

[thejeremyman9]

It's very unlikely the HPFP is failing. That's virtually unheard of; its a mechanical pump so it either works or it doesnt. When you unplug the MAF it in a way "turns off" your LTFTs. In the original log your LTFTs were +22% which was adding a bunch of fuel, potentially why you HPFP was crashing. If you are stock intake, you could have a MAF issue (can try cleaning), or a boost/vaccum leak, or something affecting trims. If you plug MAF back in and LTFTs go positive again and HPFP crashes, you will know that's the problem.

In the new logs, both LTFTs and STFTs are near 1 so you dont have the fueling issue.