reset fuel trims; lasted about 60 miles or about an hour

[workingonit]

I have just tried and failed to reset the long-term fuel trims by the Foxwell "reset all adaptations" method, twice, over thirty minutes. I had run the engine up to operating temperature, and followed the steps indicated on the Foxwell, but no success.

I went inside for awhile, then started the X5 up again, then after operating temp was reached, I paid particular attention to the MAF readings, which were pretty steady at 5.8-6.0 g/s at idle (much better than the old MAF's 4.1-4.5 g/s). I raised the rpms to about 1800 for about 3-4 minutes, and saw the long-term fuel trims fall to 7.8% on both banks (from 10.2% on bank 1, and 10.8% on bank 2). I watched for another 10 minutes at varying rpms, but the LTFT's remained at 7.8%. I had never seen them fall on their own, before the new (cheap) MAF was installed.

I am sure that longer use by driving would make the LTFT's fall further, but growing impatient, I got out and unplugged the MAF until it stalled and set a DME code. Then, I plugged it back in, returned to the X5, cleared the new MAF code, and ran the engine another 30 minutes. Here's a photo of what I saw:


I'm happy now, but only more driving and time will tell if my lean code problems are truly gone. Switching to a new MAF seems to have worked.

[X5chemist]

Back from a short trip, wow. Lots of conversations.
Keep it going. Hopefully it works out.

[workingonit]

Originally Posted by X5chemist

Back from a short trip, wow. Lots of conversations.
Keep it going. Hopefully it works out.

I've only got maybe an hour runtime on the new, cheap MAF, but so far, so good.

While actually driving the X5 (about 22 miles this morning), the LTFT's % are starting to move around a bit (from -3.12 to +0.78) but soon go back to zero. Meanwhile, the STFT's have ranged from -7.12 to +3.12, but stay mostly the opposite (+/-) of the LTFT's (making their composite total nearly zero). The MAF values go from 4.1g/s (lowest I've seen, at 745 rpm) to 36++g/s momentaily on acceleration, with a very fast response time.

Time will tell what the end result will be, but I've never seen it display negative long-terms before. I sure hope my lean codes stay away, but also that they're not replaced with rich codes!

[andrewwynn]

I still have my original Siemens brand MAF that was working fine when I replaced it. (Big oversight I could have swapped when I gave the car to the insurance co. )

[workingonit]

Originally Posted by andrewwynn

I still have my original Siemens brand MAF that was working fine when I replaced it. (Big oversight I could have swapped when I gave the car to the insurance co. )

If the cheap new MAF continues to work advantageously to my benefit, it will remain in place on the engine, but if it doesn't solve the lean codes problem afterall, then the Siemens MAF goes back on (but I'll never be sure if it is good, bad, or iffy).

I wish you had kept yours, and you could've rented it out for testing purposes.

[andrewwynn]

My old one worked exactly the same as the new one. I was chasing some odd trim issues that were likely just worn out cat so I am suggesting as you said loaner for diagnosing but also say your knock off works perfectly for a month and craps out. Mine is just sitting on a shelf and doesn't fit in either of our new x5s so I would send to anybody that could use it.

[EODguy]

Originally Posted by andrewwynn

My old one worked exactly the same as the new one. I was chasing some odd trim issues that were likely just worn out cat so I am suggesting as you said loaner for diagnosing but also say your knock off works perfectly for a month and craps out. Mine is just sitting on a shelf and doesn't fit in either of our new x5s so I would send to anybody that could use it.

Sheeeeee-it I wish I was stateside!

Sent from my SM-A730F using Tapatalk

[workingonit]

Originally Posted by andrewwynn

My old one worked exactly the same as the new one. I was chasing some odd trim issues that were likely just worn out cat so I am suggesting as you said loaner for diagnosing but also say your knock off works perfectly for a month and craps out. Mine is just sitting on a shelf and doesn't fit in either of our new x5s so I would send to anybody that could use it.

So you meant that you would send it to me? as a loaner? or gift or purchase? Sure, to any of the above! If you say it's good, then your stellar reputation assures it to be so.

I think I'd trust a proven Siemens MAF over the cheap replacement, in the long run, but for right now, I'll keep testing with it. Until it (probably) craps out.

Please PM me what arrangement you'd like, so I might acquire your MAF, on your terms. Sounds perfect for a cross-check of different MAF characteristics, a comparison that I have looked for online for quite awhile, and not found.

[X5chemist]

Keep posting data. Once I get mine back, I'll compare information.

[andrewwynn]

Originally Posted by EODguy

Sheeeeee-it I wish I was stateside!

Sent from my SM-A730F using Tapatalk

Mine is from m54 wouldn't help you.

I think I do have one from an m62 which might actually be the same and it might take forever but can't I ship using afp?