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

[workingonit]

X5chemist- thanks for your info, though I don't quite understand how to read them.

My prior understanding of ST & LT fuel trims is that when your engine is operating properly, the MAF is reporting the correctly measured airflow, and the O2 sensors are adjusting the trims to correct any imbalance, then the LT trims should become "normalized" (approaching zero added or subtracted), and the ST trims should be compensating for second-to-second changes. I haven't seen -/- on my scantools for ST/LT trims, ever (but when my old OEM MAF was setting codes, I did see +/+ everytime).
Foxwell freeze frame while using old Siemens MAF, prior to switch to cheap MAF

On my Foxwell (also on Torque Pro & Bimmertool Pro apps) I've never observed double negative -/- fuel trims on the X5, and as I said previously, my two Chevy trucks never vary from a zero LTFT. Does your scantool always report in that fashion? Do you have Torque Pro? and if so, what does it report? It would seem to me that consitently withdrawing fuel would indicate a rich condition in your engine. Did your old original MAF generate similar fuel trims to the present cheap MAF?

[X5chemist]

Wow, the load value is high for only going 36 MPH. What gear was it in? It had to be a low gear. I can use my Foxwell and an Actron scanner to compare values. Keep in mind, mine has a modified DME. As to what kind of software updates or mods it may have I don't know. The DME was replaced to disable an EWS battery drain. The BMW DME suppliers may have done some software tweaks. I do have my OEM MAF sensor. I plan to install new brakes all the way around on Thur. I can swap the MAF sensor for readings after scanning with my other tools. Looks like your FT are balanced between front and rear. So the issue of off FT is common.
How high is vacuum when you take off the oil cap at idle? I think mine is a little high. I plan to replace the CCV soon. I think it's contributing to oil loss though small. 1 Qt per 1500 miles or so. Which seems normal for a high mileage BMW engine.


Code P0365: points to the intake cam sensor. It may need cleaning or replacement. I plan to replace both intake and exhaust cam sensors during a CCV/coolant system update. Remove the intake sensor. I suspect the o-ring is failing. If it is, oil going past it is causing reading errors.

CCV test: https://www.youtube.com/watch?v=vODpt5b2DsM

Does anyone know if BMW fuel trims are positive or negative? GM on most vehicles are negative.

Good read on fuel trims: https://trade.mechanic.com.au/news/u...rm-fuel-trims1

[workingonit]

Originally Posted by X5chemist

Wow, the load value is high for only going 36 MPH. What gear was it in? It had to be a low gear....
How high is vacuum when you take off the oil cap at idle? I think mine is a little high. I plan to replace the CCV soon. I think it's contributing to oil loss though small. 1 Qt per 1500 miles or so. Which seems normal for a high mileage BMW engine.


Code P0365: points to the intake cam sensor. It may need cleaning or replacement.

Does anyone know if BMW fuel trims are positive or negative? GM on most vehicles are negative.

The freeze frame was taken in response to the P0365 code, at 36 mph (I was either accelerating really fast, or decelerating using the manual shifter settings...don't remember). I have a second instance of the same code, where the engine load was much lower, at a higher speed:
second time the P0365 showed up, engine load much lower

I've replaced the exhaust camshaft sensor (with a VEMO CPS, made by VIEROL.AG - GERMANY), and that code went away.

When I remove the cap, the vacuum seems a bit high, but not ridiculously so. I was getting an oil leak from the cap, so I replace both the cap and seal.

About never seeing both ST and LT fuel trims in the negative, I was wrong. I have a photo of where I had negatives only, soon after I installed the cheap MAF sensor:
soon after the sensor was changed

[X5chemist]

LTFT seem okay. STFT however look off. It's hard to say without more data. Especially how that article states trims should be at three different RPMs. Plus they do change over the RPM range. The DME is pulling fuel out of it. I would be curious to see fuel injector pulse width using my Power Probe IV.

[workingonit]

You can make pulse width checks, but that's out of my current skillset. And, even if it wasn't, I'm not touching anything until after I pass the emissions inspection in a week or so (prior to November). I sure don't want to jinx anything...my lean codes started a week or so after the last inspection, so I've been dreading it for nearly a year.

Thanks to you, X5chemist, for the link to the cheap $23 (now $20.99 on Amazon) that may allow my X5 to pass for another year. I can't wait until 2025, when it's "safety" only inspection time for the X5!

[X5chemist]

No problem. We are all here to get and give help when we can. Our combined knowledge helps everyone. I’ve improved my electrical troubleshooting skills learning with my X5.
Hope it passes inspection. Mine is coming up soon too. If you were closer, I would take my tools to check the injector pulse width. At least, the MAF sensor has helped a bit.

[workingonit]

Fear and Loathing of the annual emissions test is now gone for awhile:

Originally Posted by workingonit

... I'm not touching anything until after I pass the emissions inspection in a week or so (prior to November). I sure don't want to jinx anything...my lean codes started a week or so after the last inspection, so I've been dreading it for nearly a year.

Thanks to you, X5chemist, for the link to the cheap $23 (now $20.99 on Amazon) that may allow my X5 to pass for another year. I can't wait until 2025, when it's "safety" only inspection time for the X5!

AND

Originally Posted by workingonit

I cleared codes with my Foxwell last year, a month before inspection, but never drove the drive cycle, just my normal grocery shopping route (4 trips, I think). It was almost perfect on inspection day! However, a week or so afterwards, I started getting lean codes and CEL's, which plagued me for many months (almost a year). It's inspection time again, and I won't even change my oil, in fear of screwing up the monitors before it passes.

Before I took it in today, I used the Torque Pro app (always active on a spare phone on my dashboard) and saw that all emissions monitors had "completed", without having to "drive cycle" the X5. I've not even run any Foxwell tests in over a month, not wanting to accidentally screw the pooch.

Now, after a full "pass", I noticed that the LTFTs had risen to 9+ (they were at 5-6+ when I drove into the station), which makes me wonder what sort of interaction/influence the testing machine (plugs into the OBD2 port) may have on the X5's sensors or modules, if any? Mind you, my X5 passed perfectly at the same testing station last year, and the fuel trims went wacko in the next couple of days...coincidence??? We'll see.

If the fuel trims don't return to the pretest levels, I'll zero the readings and start over (and might get another MAF sensor to test). Hello, Andrew?? Maybe a $23 unit again (now $20.99 Amazon), or a VDO for $200 FCPEuro (have to talk the wife into it), or a Bremi at $100 FCPEuro. Another year of testing ahead, I see.

[Bdc101]

Originally Posted by workingonit

Hello, Andrew??

Seriously, where has that guy been? He goes and buys an E70 and thinks he's too good to hang out with the ol' E53 guys anymore

[X5chemist]

LTFT are affected by long idle times too. Right? Passed is the important item. Do they test a three different RPMs? Catalyst and O2 sensors would also affect LTFT. Mine is coming up on inspection soon. Since I've been tracing down a small coolant leak, I'll connect the Foxwell. It has been idling during testing.

[workingonit]

Originally Posted by workingonit

... I noticed that the LTFTs had risen to 9+ (they were at 5-6+ when I drove into the station), which makes me wonder what sort of interaction/influence the testing machine (plugs into the OBD2 port) may have on the X5's sensors or modules, if any? Mind you, my X5 passed perfectly at the same testing station last year, and the fuel trims went wacko in the next couple of days...coincidence??? We'll see.

If the fuel trims don't return to the pretest levels, I'll zero the readings and start over (and might get another MAF sensor to test)....

Two weeks later, and after extensive idling before & after the oil change 5? days ago, I drove the X5 on a 13 mile round-trip to vote. Before the oil change, and after the inspection trip related above, my LTFTs were sometimes at 9+, and my recently reset fuel mpg was at 14.2 mpg. When I completed the extended idling following the oil cange, the LTFTs had hit 10.18 on bank 1, and 9.68 on bank 2, while the mpg showed 13.5 mpg. Extended idling isn't good for this old engine, I guess.

But, after I returned from voting, the LTFTs were both back to 4.5 or so, and the mpg showed 14.2 mpg. I guess you're correct on your assertion, X5chemist

Originally Posted by X5chemist

LTFT(s) are affected by long idle times too.

I'm wondering whether other factors had a part in such a quick reduction in fuel trims, like

• 1) fresh, clean, high-quality oil in the crankcase,
• 2) a fresh fill-up with Quik Trip Top Tier premium gasoline (the previous fill was over six months prior), and/or
• 3) a full treatment of STA-BIL 360 Protection Ethanol Treatment & Fuel Stabilizer (1 ounce per 5 gallons, or slightly more)

Whatever the cause, I like the results.