X5 stalled/set codes while being inspected!

[workingonit]

I'm hoping to get the emissions monitors set and get the X tested before Sat Nov. 1, but there's a 7 day grace period afterwards, so I have some time to get the odd behavior sorted out.

I'm only concerned about the two times it semi-stalled and the STFTs swinging between +/- 28.5 under hard acceleration. Also, it once had a delayed shift (hung in gear) going uphill under hard acceleration. Never had any problem with the transmission before.

I'm hoping that resetting the adaptations will work miracles.

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[andrewwynn]

Under heavy acceleration uphill it's pretty normal to stay in the current gear up to redline depending how heavy your right foot.

If your dash gauge doesn't match fuel level, use test 21


–awr–

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[workingonit]

Originally Posted by workingonit

...
Problems? the X5 almost stalled twice (once backing out of my driveway, second time leaving the gas station onto a secondary highway)...it never previously did that. Plus, now, the accelerator is extremely responsive, with no hesitation (which it had before), so much so, that I thought it was in Sport Mode (making downshifts) or someone installed Nitrous on the M54, it was so much. And, there was another difference....

I've been chasing lean fuel trims for 4 years now, unsuccessfully, but they've been brought mostly under control sfter X5chemist donated a "proven to work" Siemens MAF to me (thanks again!). I monitor them constantly on my dashboard-mounted Android tablet running Torque Pro. The STFTs bounce from about +4 to -10, to adjust the LTFTs that stay in a +3 to +8 range (plusses indicating a lean condition). To my astonishment, I'm getting rich condition numbers, now.

While the LTFTs have started to waffle between -4 and +4, the STFTs are all over the place, and have gone as far as -28.5 aty times, under acceleration. WTF

Even at idle, inthe driveway upon returning home, it still looks odd (rich) to me.

Another day...

I reset adaptations, as advised, then took it out on a 22 mile drive cycle (but mostly stuck in a stop-and-go freeway back-up situation). No progress towards a successful inspection, but seemingly headed in the other direction.

It drove fine for a mile, until I reached the hilly curved section near my home, whereupon it took off like a scalded dog, and set two faults and the SES light. i drove it another mile to a parking lot, where I read the codes P0172 and P0175, both RICH codes, on my Torque Pro app (doesn't give BMW-specific codes). I cleared the codes, and SES light, and carried on wit my drive.

Again, the X5 showed increased power & firmer shifts (probably partly due to reset adaptations), and the LTFTs steadily went from -4.69 on both banks, to -8.59 on both banks (where it stayed for the remaining 20 miles, and still is there at idle, in my driveway). The STFTs were a little better, I think, than last time, never reaching past -12.5 (as opposed to -28.5, previously) and often were going positive, as far as 8.5, once in awhile). Progress ?

I could live with rich fuel trims, as long as the SES light stays off, just long enough to pass this year's inspection...its' last (I had the oppossite problem with lead fuel trims for the last four years), but there were two glitches in driveablity, as I returned home.

At the same spot that it had accelerated too much, and then hung in gear returning home the other day (uphill left 90-degree curve), it seemed about to stall or go into limp mode for about 10 seconds following the curve, but it regained power just in time to do the same thing, on a flat 90-degree curve (right) that followed. Full power came back quicker, as I approached two full turns and my driveway in a left-left-right pattern over 600 yards.

I sure DON"T want stalling nor limp mode around my area, because of the narrow country roads with no turn-offs, and limited visibility (and tailgaters driving way over the posted speed limits).

Another thing, my O2 sensor monitor won't complete now, but it has always completed within 15 minutes or 15 miles of driving, previously. I'm hoping for some progress tomorrow (if I decide to chance driving a posslbly stalling X5).

OR should I just buy a fuel filter with regulator...it's the one item that could control over-fueling where there was under-fueling, before.

Here are today's Torque Pro displays vs yesterday's:
yesterday, emission monitors nearing completion
today, o2 monitor not completing
yesterday, 1st sign of rich conditions
today, rich LTFTs stuck at -8.59, worse?

[andrewwynn]

Have you measured fuel psi yet? If it's over 50 FPR is shot and will cause rich mix and negative trims.

The MAF can send incorrect value to cause a similar problem also but I thought i saw you tried a couple different ones.


–awr–

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[workingonit]

Originally Posted by andrewwynn

Have you measured fuel psi yet? If it's over 50 FPR is shot and will cause rich mix and negative trims.

The MAF can send incorrect value to cause a similar problem also but I thought i saw you tried a couple different ones.


–awr–

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No, I haven't yet found the adapter I bought to fit the Schrader on the fuel rail. If I don't find it tomorrow, i'll order another.

Years ago, on 5-11-2022, when I measured pressure, it was

barely at minimum, IIRC. But, i didn't have misfires, hard starts, or long crank times, and only had the mysterious lean fuel trims (that everyone assured me was a vacuum leak...never found one).

Now, with a new fuel pump, and suddenly running super-rich, it doesn't look like a vacuum leak anymore.

What sort of fuel pressure would cause those fuel trims I'm now getting? and the surges of power, and/or the stumble/stall/limp mode following those 90 degree curves?

After using cheap $20 MAFs to combat erroneous fuel trim numbers (trying anything to do a workaround, since I never found the root cause of the lean trims), X5chemist showed pity for me and offered a proven-good, OEM Siemens-VDO MAF for me to use, at least until i could find the true cause of my lean fuel trims.

the Siemens-VDO MAF was giving me fuel trims that were much more normal, and I was quite happy with those numbers, and had thought that perhaps it wasn't a MAF problem, or even a vacuum problem, but maybe an injector problem (but why in both banks, with injectors only <5k miles old?), and I was using more and stronger fuel system and cat cleaning additives to try and fix the flow; I should've reasoned that the fuel system further upstream was the culprit.

[80stech]

The only way the fuel pressure regulator can provide more fuel is if the diaphragm is shot and then you will fuel going up the vent line to the intake boot, easy enough to check. The other only way would be that somehow the vent line is plugged and pressure is building up in the regulator, or you have that vent hooked to pressure somehow. If I had to throw out a guess I would say MAF. How do you have <5k on the injectors ??

[workingonit]

I'll check the intake boot tomorrow for fuel (coming up the vacuum line?), and use a pump to suck air or fuel up the line going from the F-connector to the FPR. We'll see what comes out.

The Bremi injectors were installed new by my neighbor during the 3.5 year period when he was refurbishing the X to swap for my Chevelle. I figure he might've put up to 3k miles on it, and I've just now passed 2k miles (in the 4.5 years I've owned the X)

[80stech]

Wrong or bad injectors would explain some things.
It might be pretty obvious when you pull that vent line off and gas comes out. To get an idea of how the regulator works put a vacuum pump (or a bit of pressure) on the line to the regulator while you are monitoring the fuel pressure and see how it changes.

[workingonit]

1) Was the new fuel pump pressure so much greater than the old pump, that it might've blown the diaphragm in the FPR (allowing/forcing excess fuel forward), or is it just a coincidental thing to installing a new pump?

Though I don't believe in GOOD coincidences, my life history is full of BAD ones, usually coming in threes. For instance:

• a) fuel pump replacement coming at the time I needed to get inspection, and now I'll be working on it for awhile to come
• b) had to bury one of our dogs on the same day, getting poison ivy at the same time...missing the young guy, and hating the poison ivy (I thought it was too late in the season to get it), and
• c) my new (4 months old) phone hasn't been charging for two days, but I finally fixed it, just now...is that three, or more?

2) After looking at multiple videos about changing a fuel filter/FPR on an E53, is there a way to squeeze under the shield/modify it, so that a crippled old man can do it while laying on plywood in his driveway? i would've already done the job three years ago, but it looked to be a bear, and I waited (perhaps too long). Not only is my fuel system paying the price of the delay, so is my body.

3) I understand how excess fuel could cause surging and rich fuel trims, but where does stumbling/stalling/going into a partial limp mode figure in? and only after a sharp turn or a sharp curve? I can't figure that one out.

[andrewwynn]

Ever fix your siphon jet and was fuel near 2/4-3/8 tank?


–awr–

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