negative fuel trims, not hitting full boost.

[nickw8855]

i have been dealing with the headache of a problem and so this is my first time posting here. a few months ago the 6 really started acting up. fuel trims started hanging out around -15 on both LTFT and STFT. boost would only get to 12psi WOT (tuned for 22). High pitched squeal coming from hpfp. Not hitting desired HPFP psi (demand is 1660 and only sending 1400psi. ) AFR's hangout around 14.5-14.7 at idle. here's some logs. I'm a dummy so any help would be appreciated. I've spent days on these forums trying to look through threads and have replaced so many darn sensors, I'm tired of throwing money at this thing. I should also add, recently HPFP rebuilt, new CS injector seals, new spark plugs @.026 gap, new pcv, new prv, cant find a boost leak. no check engine lights.

 

[Enki]

Did you rebuild the HPFP just before the issue started? How was the rebuild done/what was done to the pump?
Pressure starts low then jumps up for seemingly no reason at idle, but the other logs look like it pretty much hangs out around 1400. Meanwhile, STFTs are pulling fuel pretty hard.

Not sure if stuck open injector (I would think this would show up in the idle log as an oscillation) or a leak on the high pressure side somewhere, or if your pump was installed off-kilter or something (I've done this before).

Does the engine bay smell like fuel when it's running?

 

[nickw8855]

Did you rebuild the HPFP just before the issue started? How was the rebuild done/what was done to the pump?
Pressure starts low then jumps up for seemingly no reason at idle, but the other logs look like it pretty much hangs out around 1400. Meanwhile, STFTs are pulling fuel pretty hard.

Not sure if stuck open injector (I would think this would show up in the idle log as an oscillation) or a leak on the high pressure side somewhere, or if your pump was installed off-kilter or something (I've done this before).

Does the engine bay smell like fuel when it's running?

the rebuild was done with CS HPFP internals and O-rings, I rebuilt it after problems developed. the engine bay does not smell like fuel and aside from the high pitched noise on cold starts coming from the HPFP area it sounds like it always had for the 5 years I've had the car. at this point I think it may be a LPFP problem as KOEO the HPFP is only getting 39psi. either that or what are the odds the HPFP lobes or cam followers are damaged?
.

 

[Enki]

Cold start chirp is something that can be tuned out; its basically an overpressure situation and the sound you hear is the PRV venting.


Assuming the following is true:
1. No fuel smell in engine bay when hot
2. PRV has been replaced with a known good one that runs factory (1800 PSI) pressure
3. Fuel rail pressure sensor has been replaced (with OEM, not a "close" or "similar" part number as those may not read properly on these cars; this is a documented thing elsewhere on the forum)
4. No other changes had been made to the car prior to this issue cropping up

This may actually be an injector problem, unless the check valve in the bottom of the HPFP (where the high pressure line connects to) is kaput. I think I've heard of that exactly one time, and it's a pain in the ass to pull that sumbitch out, but may be worth a check. If this *IS* the issue, then a simple cleaning may get you back up and running. Might be able to test this with an air compressor fitting and gauge.

 

[nickw8855]

Cold start chirp is something that can be tuned out; its basically an overpressure situation and the sound you hear is the PRV venting.


Assuming the following is true:
1. No fuel smell in engine bay when hot
2. PRV has been replaced with a known good one that runs factory (1800 PSI) pressure
3. Fuel rail pressure sensor has been replaced (with OEM, not a "close" or "similar" part number as those may not read properly on these cars; this is a documented thing elsewhere on the forum)
4. No other changes had been made to the car prior to this issue cropping up

This may actually be an injector problem, unless the check valve in the bottom of the HPFP (where the high pressure line connects to) is kaput. I think I've heard of that exactly one time, and it's a pain in the ass to pull that sumbitch out, but may be worth a check. If this *IS* the issue, then a simple cleaning may get you back up and running. Might be able to test this with an air compressor fitting and gauge.

-Prv was ordered through edge auto
- fuel rail pressure sensor was replaced with h a Bosch 0261545038
-wpuld it be easier to completely replace the hpfp entirely?

 

[Enki]

-Prv was ordered through edge auto
- fuel rail pressure sensor was replaced with h a Bosch 0261545038
-wpuld it be easier to completely replace the hpfp entirely?

1. Good job
2. This is a 3000 PSI sensor; you should have read more of the thread you found it in. This is likely the culprit of your low pressure and high trimming reads.
3. No lol the only things that generally fail in these are the internals (for the most part). You can probably get a junkyard spill setup for under a hunno.

 

[nickw8855]

I see, okay, I'll verify that's the one and just order a new OEM one then

 

[Enki]

I see, okay, I'll verify that's the one and just order a new OEM one then

New OEM one comes with a fuel rail and will be super expensive. Just read all of that thread I'm assuming you found the part number you're currently using in.

 

[nickw8855]

New OEM one comes with a fuel rail and will be super expensive. Just read all of that thread I'm assuming you found the part number you're currently using in.

So I may be missing something. I read through the entire host multiple times and it's still saying to use the *53 which is currently in there. What am I missing? Should I just try to track down a used OEM sensor?