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

[workingonit]

I accidently reset my fuel trims, by unplugging the MAF sensor repeatedly several times while it was running. The very high long term fuel trims went to zero, and the short terms stayed low while idling. Well, I finally found out how I accidently reset my fuel trims...it was by repeatedly unplugging and re-plugging the MAF sensor
https://www.e46fanatics.com/threads/.../post-14695303

Originally Posted by wamcdonald

With car running disconnect the MAF sensor wait a few seconds and reconnect it, that's it. The car may stall but just re-start and you may through a MAF code but this gets the values back to zero.

I hate mysteries, so that's reassuring that it's been done before, with the same results.

That was over a week ago, and today I took the X5 on a >100 mile trip, just to see how long/how many miles the "reset" fuel trims were good for; I refer to this previous post, where I pondered this question: https://xoutpost.com/1219167-post35.html.

Now I know...if I haven't solved the SES light problem, as triggered by P0171, P0174, and P0313 codes (where the fuel trims are very high) before inspection time in October, I might have as long as 60 miles and/or about an hour of drive time before the fuel trims go sky-high again, and set off the SES light (I saw and marked the time and mileage as the SES came on).

andrewwynn had suggested the reset adaptations may be able to gain a week's grace period, as a grace period at inspection time;

Originally Posted by andrewwynn

reset adaptations may get you a week or more no error code to get an inspection pass while working out the problem

what adaptations he meant, I don't know, but while I'm trying just about anything to resolve the problem (visual inspections, smoke test(s), carb cleaner spray test, MAF cleaned and tested, O2 sensor functions tested OK, etc.), with no problem source found, I'm willing to cheat a bit to pass the test.

My X5 is just under 21 years old, runs perfectly fine, no hint of a smelly or rich exhaust (to my senses), and though the scan tool says that there is an infrequent lean misfire, my "seat of the pants feel for the car I'm in" tells me no such thing. It runs smooth as silk at any speed, from a 700 rpm idle to 80 mph.

Anyone care to venture a new approach? or will I end up praying to get a one hour or 60 mile window of opportunity, where my X5 can pass inspection? If it was just 4 years older....

[andrewwynn]

With my foxwell scanner I can reset adaptations in the service main menu I think. (I never remember the exact places). I am sure the think diag will also but I'm likely to let the subscription expire on that. The foxwell is more reliable even though I do like the iPhone interface.

Have you checked your fuel pressure under load? Pumps at end of life just get weak. The FPR hides their failure for an extended time, often after more than a year you just start getting lean codes that aren't MAF or vacuum leaks.

The car measures how much fuel by assuming 50.00 psi.

If its less, even if just under high throttle you'll get lean condition. Watch a graph of your O₂ precat and see if they go lean under heavy throttle that's a big clue.

[workingonit]

Originally Posted by andrewwynn

With my foxwell scanner I can reset adaptations in the service main menu I think...Have you checked your fuel pressure under load? Pumps at end of life just get weak. The FPR hides their failure for an extended time, often after more than a year you just start getting lean codes that aren't MAF or vacuum leaks.

The car measures how much fuel by assuming 50.00 psi.

If its less, even if just under high throttle you'll get lean condition. Watch a graph of your O₂ precat and see if they go lean under heavy throttle that's a big clue.

In one of my posts I said I saw a "reset adaptations" somewhere in the service section, on my Foxwell 510, but was afraid to do it (it said reset ALL adaptations). Not knowing the full scope of adaptations involved, I didn't want to screw-up some other adaptation that was beneficial to the operation of the X5. I'll have to revisit the service section next week, after I return from my trip.

Once, I had trouble with my '04 2500 HD re-learning, after just fixing something or other (15 years ago, I can't remember what it was, but that it made the 120 mile round-trip commute very interesting the next morning/afternoon....)

Concerning fuel pressure, that could be why the P0313 code sometimes appears, along with P0171 & P0174. P0313 is when the PCM has detected a misfire in one or more of the engine's cylinders along with a low fuel reading in the fuel tank. I've been meaning to get this one, which I believe has been recommended on this forum


As I stated above, I've been getting "lean codes that aren't MAF or vacuum leaks". Here's an O2 graph I made earlier;


does it show what you're talking about here?

Originally Posted by andrewwynn

Watch a graph of your O₂ precat and see if they go lean under heavy throttle that's a big clue.

I have no maintenance records for this X5, and the guy I got it from didn't touch the fuel system at all, focusing on (in order) cooling system, suspension, axles, exhaust, "cracked" windshield, & timing chain/guides (plus other stuff). He didn't know what the previous owner had done, except for screwing up the radio (though he had kept the high-mileage truck moderately well serviced, with 4 of 6 door locks OK, all windows & lights working, A/C perfect condition, etc.).

This nagging problem is something that appeared 5 months into my ownership, but not prior. It may just be as you say, time for the FPR to get weak.

[andrewwynn]

The reset all is the one. Some scanners will have fuel adaptation foxwell doesn't.

Tye O₂ trace shows what I described. I haven't done a trace in a while. Usually you'll get a trace peg high or low when you get off throttle and coast or wot but uner load say going up a long hill the pre cat should bounce up and down a few times a second spending about the same time up as down.

Definitely get a fuel pressure gauge. On e53 petrol model the pressure should be dead flat 50.0 ± 1psi (but stay steady e.g. 49.5 ± 0.05). Usually it's the FPR which has an internal o-ring that fails but second most likely is fuel pump wearing out.

Divide your total miles by your long term average speed. Eg 150000/28.5=5263.158.

Pump should last 5000-5500 hours. 6000 if lucky.

(Reminding myself my new to me e70 is about 148000/5500=26.909 so I'm probably due for a fuel pump soon. I'll maybe order to have one on hand when it fails. )

[workingonit]

210620/28.6 (these numbers are from memory, but very close to actual)=7364.33 hours, if original. It probably isn't though; surely the original owner replaced it in the past. However, the problem started surfacing on hard(er) braking on a turn, followed by acceleration, or on a sudden evasive manuever, followed by hard acceleration.

Today's SES trigger occurred when hard braking at the merging of lanes of traffic near a wreck scene, though I had been expecting the SES to appear at any time, as I watched the fuel trims grow steadily higher, with long-terms already at 11.72% each, and the short-terms fluctuating between -2.36 % and 10.17% (as observed).

I'll have to put aside some of my spending money from my upcoming camping trip, and buy the fuel pressure test kit, secretly. My wife says I buy too many things for an old retired guy (money that she wants to spend!).

[andrewwynn]

You can likely borrow the tester from auto parts store

[RocketyMan]

On your MAF and in neutral with literally no engine load, what is your g/s on your MAF holding the engine RPM at exactly 1000 rpms? What about at 1500 rpms. Then what about at 2000 rpms.

[workingonit]

Originally Posted by RocketyMan

On your MAF and in neutral with literally no engine load, what is your g/s on your MAF holding the engine RPM at exactly 1000 rpms? What about at 1500 rpms. Then what about at 2000 rpms.

I went outside to prepare my camper for my trip, and since I had to move the X5 aside to pull the trailer out of the garage, I grabbed these photos of my Torque Pro-dedicated phone in the X5.
the usual suspects

MAF graph at 1k, 1.5k, 2k rpms

I had trouble keeping the speed exactly on the marks of 1k, 1.5k, and 2k rpms, but it is close enough. 1k yields roughly 6 g/s, 1.5k yields about 8 g/s, and 2k rpm yields slightly over 10 grams per second.

Since a rule of thumb on a MAF's air flow rate at 500 rpm is 1 gram per second per liter of engine displacement (or 3g/s for my 3.0l), my graph is just about right at 6g/s at 1k rpms, a bit low at 1.5k rpms, and really low at 2k rpms (it should be 3x4=12 g/s). Am I reading this correctly? I did read the MAF momentarily, while driving at 70mph yesterday, it read 20+ g/s. I forgot the rpm, though.

[RocketyMan]

Originally Posted by workingonit

I went outside to prepare my camper for my trip, and since I had to move the X5 aside to pull the trailer out of the garage, I grabbed these photos of my Torque Pro-dedicated phone in the X5.
Attachment 82040 the usual suspects

Attachment 82041 MAF graph at 1k, 1.5k, 2k rpms

I had trouble keeping the speed exactly on the marks of 1k, 1.5k, and 2k rpms, but it is close enough. 1k yields roughly 6 g/s, 1.5k yields about 8 g/s, and 2k rpm yields slightly over 10 grams per second.

Since a rule of thumb on a MAF's air flow rate at 500 rpm is 1 gram per second per liter of engine displacement (or 3g/s for my 3.0l), my graph is just about right at 6g/s at 1k rpms, a bit low at 1.5k rpms, and really low at 2k rpms (it should be 3x4=12 g/s). Am I reading this correctly? I did read the MAF momentarily, while driving at 70mph yesterday, it read 20+ g/s. I forgot the rpm, though.

Just now getting back to your message.

So you're correct in your assertion. So the faster it was idling (with no substantial engine load) the more air you should be getting at an interpolated rate that corresponds to your engine displacement.

For your vehicle, this seems to make sense and coincide with the two fault codes of "lean" since your MAF is reading low in this case. I would suggest searching for a common vacuum leak of some sort. Sometimes you can tap on the MAF and if the reading jumps--it's a bad MAF.

But besides that, what have you done since? Did you inspect for any leaks? The intake boot? How about DISA gasket?

[workingonit]

Originally Posted by RocketyMan

... your MAF is reading low in this case. I would suggest searching for a common vacuum leak of some sort. Sometimes you can tap on the MAF and if the reading jumps--it's a bad MAF.

But besides that, what have you done since? Did you inspect for any leaks? The intake boot? How about DISA gasket?

Actually,

• 1) I did the smoke test 3x before it broke,
• 2) then a complete MAF cleaning (with MAF cleaner, of course...also verifying that it is a genuine Siemens/VDO 5WK96132Z),
• 3) then the carb cleaner spray-down (of all vacuum lines, intake boots, injectors & o-rings, etc., including the totally rebuilt DISA that I used the GAS kit on...with new gasket, too, recently), and
• 4) also spraying the SAP & even the brake booster hoses (inadvertently spraying the aux water pump wiring, which triggered a weird code),
• 5) replaced the seeping oil cap and gasket (there was an oily streak going straight back on top of the beauty cover), and
• 6) repeatedly disconnecting and reconnecting the MAF while running, which reset my fuel trims (for awhile, at least).

All those actions occurred two weeks before I started this thread. Then there were doctor appointments, then the mysterious flat tires, then the camping trip, followed by resting for a few days. I'm ready for the next round of futility!

I agree that my MAF readings are a bit low, but I'll try tapping/wiggling the sensor and the plug, to see if it affects the idle.

And, Effduration and andrewwynn, I think both of you are correct, and I'll have to do a manual test on the fuel rail. But, will the tester kit at Harbor Freight have the correct Schrader valve adapter?
The only test kit I've read about on this forum that had the correct fitting was the OTC 5630.