Xoutpost.com - 2003 X5 stalled while driving at low speed

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Long Term fuel trims at -8% ??

That's not right...that tells me it is running RICH.. The minus sign says that based on O2 readings the DME is removing fuel from the air/fuel ratio.

Ideally, the Long term trim should be about +2-3% after warm-up.

I would check fuel pressure at the rail...should be close to 50psi...We had a bad batch of Hengst fuel filter/regulators that resulted in 60 psi and a rich condition.

If your fuel pressure is good..Get your injectors tested or replaced.

It's amazing how much difference a scan tool that reads all the codes can make! I used to lead with the scan tool question but now take it for granted I guess especially with people that have been on the forum for a while. I have worn injectors and my M54 gets to -10 fuel trim where it turns on the CEL but no stalling issues. It would be nice to get an answer from the OP about the Siemens injectors though??

Quote:

Originally Posted by Effduration (Post 1248208)

Not good news for my situation, having just bought a Hengst FPR/filter, last month. Hope it's not bad out of the box.

While my health is keeping me from changing out the filter right now, in preparation for a fuel system refresh, from tank to injectors, I got mine from Amazon (and a Vevor cordless ratchet) using a gift card, hoping that it would help fix my fuel delivery problem.

After installing a new fuel pump, my M54 went from running lean to running rich (like the OP's X), and stumbles on hard turns, and when I last checked fuel pressure at the rail, it suddenly dropped to zero, leading me to suspect a partially plugged up filter (original, probably filled with debris after using Jectron and Cataclean in combination), or a FPR gone bad. Hence, getting a Hengst!

I should have bought a Mahle, but I try to get good but cheaper OEM quality parts if possible.

Sent from my moto g power 5G - 2024 using Tapatalk

@workingonit
Fuel pressure suddenly dropped to zero isn't the filter. Did you post that in your thread ?

sorry to hijack the thread, but

Quote:

Originally Posted by 80stech (Post 1248212)

@workingonit
Fuel pressure suddenly dropped to zero isn't the filter. Did you post that in your thread ?

Yep, I did, in post #108 of my thread (as posted on 11-15-2025) https://xoutpost.com/bmw-sav-forums/...inspected.html

Quote:

Originally Posted by workingonit

Meanwhile, about fuel pressure testing:
The tester gauge was left on the windshield for 22 hours before I tried starting the X today. It read 36psi.
Attachment 85148

I bled the pressure, then started the engine, and it took about a minute for the needle to rise to 44psi, never reaching 50. I pushed the bleeder button again, got very little fuel from the bypass hose, and looked at the gauge again (after jumping back into the seat). It read ZERO. So, I tried again, with the same results, ZERO psi.

Then, I removed the gauge and extension hose from the gauge, and went through another round of key flip/clear codes/finally restarting, before I attached the fuel gauge to the fuel rail, sans extension. Still no pressure. WTF?

Today's conclusions: I'm jinxed, hexed, cursed, damned, whatever, after trading my Chevelle (that brought a Poltergeist into my garage, as witnessed by four others). I believed, at first, that the Poltergeist left with the Chevelle, but maybe not. I thought we had a truce, at least, but....

More seriously (I hope):

1) maybe it's time for another diamond key rebuild; I have a key shell (with the blade already laser-cut), so maybe a new battery and guts transferral is in order,
2) I guess I need another fuel pressure tester kit...I'll try a name brand this time, etc

I got another fuel pressure tester (Performance Tool W80595), but haven't tried it yet. Or tried ANYTHING in two months. My arm is finally feeling better, and the Dr. hasn't recommended surgery, so I'm planning to get back at it around Feb1.

Quote:

Originally Posted by 80stech (Post 1248202)

Does that personal friend of yours know anything about the M54 Siemens injectors having ceramic seats that can be damaged by ultrasonic cleaning ?

Btw, yes, he does. He has very expensive equipment which works at higher Hz, which does not cause issues.

I noticed yesterday that also while off throttle and slowing down, my little fuel economy gauge is jumping. Usually off throttle and coasting it just goes to the far left, like showing 40+,.but now I see it pulsing toward the wright side even though I'm off the throttle..so something - some sensor is telling the DME to pulse fuel I think. But meanwhile the car is not jolting forward.

I'm wondering if I'll get any fresh DME codes after the next time it stalls. I was also advised that I shouldn't be driving around with this bc it could potentially cause other issues. Ugh.
.

You might want to rig up a fuel pressure gauge attached to the schrader valve with a hose long enough to view while driving...strap it to the wipers on a dry day...

Did you clean up the DME connections ?
Grounds, engine and 2 on the coil harness?
Not a good sign when your INDI can't read the codes.

This morning I was thinking about the ignition switch, not the key switch, but the other on the left side of the steering wheel. I did have one stored error voltage supply terminal 15. But also thinking logically, this wouldn't only happen low speed off throttle and cause my rpm/fuel economy jump. Logically that would be more similar to a vac or air leak, or something. Too cold to do anything but read and Google!!!

Meanwhile, got a replacement air intake resonator for my 06, which was deformed and not mating properly with the MAF and gasket. That car needs full front control arm rebuild, but I have mechanic do that stuff since I don't have proper lift.