P1093 SEARCH FOR A FIX CONTINUES...

[upallnight]

Originally Posted by docnabimmer

Hey R

you still battling this code,hoping that exhaust repair fixes it.
154790 miles and no P1093 code since.
Another Engine failsafe problem for the past year though but a new MAF VDO Siemens has so far kept that light off.
R

[mendes9]

196K, I'm in the same boat P1093 bank 2 ... I'm going to try a clear adaptions with ISTA. I did it with my autel but didn't work. Replace both O2 sensors on bank 2, but no reason to believe they are bad as they respond fine. Output voltage on downstream o2 is low at times, and bank 2 fuel trim is slightly high at 7 to 9% (again at times), both long term fuel trims are below 1%. 3 months until inspection expires.. the clock is ticking.

[workingonit]

Originally Posted by mendes9

196K, I'm in the same boat P1093 bank 2 ... I'm going to try a clear adaptions with ISTA. I did it with my autel but didn't work. Replace both O2 sensors on bank 2, but no reason to believe they are bad as they respond fine. Output voltage on downstream o2 is low at times, and bank 2 fuel trim is slightly high at 7 to 9% (again at times), both long term fuel trims are below 1%. 3 months until inspection expires.. the clock is ticking.

Never read this thread before, so here's my 2 cents input.

I've never had a P1093, but initially, before I started doing MAF resets, I was having repeated problems with P0171 and P0174 (lean codes) going so far above normal range that the SES (CEL,MIL) would trip. This started just following inspection in late Oct '21. For the last four years I've been trying to find what's wrong, and though the fuel trims have sttled down a bit, I'm still looking.

Many smoke tests, fuel pressure tests, MAF sensor resets and/or replacements, DISA rebuild, ICV tests and cleaning, etc. (plus some experiments that could've fried my DME, but didn't) later, like mendes9, i'm going to do more testing, as is my habit, this time of year.

It's because I'm three months away from another yearly inspection/emissions check (fortunately, the final one required for my '01 X5, which will be 25 next year, not subject to testing), and I always fear that the SES light will appear while at the inspection station. I have been resetting the MAF, then completing the "drive cycle" and immediately driving to the station, for the last few years.

Maybe not so, this year. X5chemist magnanimously sent me his used "Siemens/VDO" MAF sensor for me to use while testing start with post#43 https://xoutpost.com/bmw-sav-forums/...ml#post1245039, and though I've not driven many miles since (probably under 300), and had to reset the DME twice during that time (Trifecta once, battery disconnect once), no more lean codes have appeared.

I tried using my original Siemens MAF until it went completely off the rails, and two other cheap $20 MAF's that would be good for awhile before I had to reset the MAF/fuel trims (I cleaned them and carry them in my trunk as spares, just in case), but it seems that my M54 really prefers a Siemens MAF. Your engine probably does too.

If X5chemist wants/needs the MAF back, I'll probably try an alternative (German-made brand) from FCP Euro, ECS Tuning, or even Rock Auto, since my non-existent budget keep me from buying a genuine new Siemens or BMW-OEM MAF. The $20 cheao units from Amazon were useful, but not quite good enough for the tastes of my X5. I'm still hoping (but not expecting) to find the root cause of my elevated fuel trims...LongTerm from +3 to +8%, usually, lately, at any speed, with ShortTerm trims trying to balance those numbers. I'd like to see LTFT's stay around zero, like my '04 Chevy 2500HD 6.0L engine has, always.

[mendes9]

I've don fuel pressure tests perfect at 50PSI, i've swapped downstream sensors (replaced both on bank 2). I've smoked tested from intake, and from tail pipe no leaks (smoke test from tail pipe does have small leak but it's after downstream O2 sensor. MAF doesn't make sense why wouldn't it effect both? Have to keep testing. Question, when you say reset the MAF, what do you mean exactly?

[workingonit]

As stated above, I've unplugged the MAF sensor many times in the past, when the cumulative values (LTFT + STFT, for each bank) would go past 20 (maybe 25, it's been awhile, so I forget which), and prevent the SES/CEL from happening. I didn't want to go into limp mode, especially if I was far out of town.

That's also the reason I had 3 MAF sensors with me for 3.5 years, and would swap in a fresh, clean one after reset. That worked OK, if not perfect, until my oreiginal OEM Siemens MAF went nuts and instantly set codes, & SES, and caused driveability problems once, out of town, and I had to quickly exit the highway to insatll a backup.

That was just prior to X5chemist sending me his spare Siemens MAF, which I'm testing (if ever so slowly). So far, the X is seeming to relearn, keeping the fuel trim number reasonable, but still on the lean side.

[X5chemist]

I have not read through the post in a long time. Was compression checked on all cylinders? I've never seen that code on any vehicle I've worked on. I'm curious to see a resolution.

[mendes9]

Ok, so what you meant by a "MAF reset", is simply you unplugged the MAF sensor.

So yesterday I reset adaptations using ISTA, you get 3 options 1, 2 or number 3. I choose number 1 which should reset all adaptions. I know it worked because after I restarted the car, the car did the crank sensor re-learn procedure (car cranks for a little before it starts). When I checked the fuel trims long term were now at zero also. I restarted the car maybe a couple times since the adaptations clear yesterday, and today when I started the car, the P1093 was gone and the SES light was out by itself I didn't clear it. Now, I expect it will probably come back, but as is using this trick I should be able to get by inspection. In my state you can go 3 months early before it's due, so in September i will use this again unless I actually find the root cause of this. Note, I cleared adaptations already using my Autel MK808 maybe a month ago, but now doing it with ISTA I know it didn't work, because after restarting the car it didn't do the crank sensor relearn. I may try it again, the only differnce was with ISTA the car was running, and when I used the MK808 it wasn't running, not sure if that makes any difference. Anyway, this may be a good work around for anyone else facing this issue and needs to get through emissions inspection.

[80stech]

Adaptations should be reset with engine not running AFAIK.