experimental MAF reset switch: which circuit to interrupt? PLAN REVISED

[workingonit]

I just got back from the family event. It wasn't at the ranch. 40+ miles south, but ended up being another 30 miles away, at a roadhouse in the southwest of Granbury Texas. I drove the X down there as planned, following the wife to the ranch, and then changed out #1 cheap MAF for the old Siemens MAF.

Why? The #1 cheap MAF didn't get better LTFT numbers at highway speed, which I had expected, but they got 3 points higher??? So, while everyone was deciding who rides with who, and who takes granny's rolling walker along, I decided to reinstall the old Siemens MAF for the second phase of the trip (the X5 was selected to haul the rolling walker, my wife, and myself.

It took me 5 minutes to change it out, reset the trims to zero, and though my wife and I didn't know where the second location was (just a general idea) we were left far behind, having to close and lock three gates.

So, with no time to pre-test after the MAF swap, I drove rather quickly down unfamiliar roads, and to my chagrin, the Siemens MAF was even worse than I remembered...the grams per second was all over the place, high where it should've been low, and vice-versa, and the fuel trims started bad and got worse, setting a SES light within 5 miles. The X5 still ran great, hitting 80 over unfamiliar two lane roads (I was playing catch-up), but I expected to go into limp mode before I reached the destination, but it didn't.

At the roadhouse, in the parking lot, I used Torque Pro to clear the codes (P0102 I think, and P0171 & P0174 as expected). I had my Foxwell in the trunk, but the Torque Pro app was already active, so I used it.

Then, it took me 4 minutes this time, to install #2 cheap MAF ( never used before), and went into the roadhouse, without any testing, once more.

After a few hours, granny (who's only 9 years my senior) was getting tired, so my wife volunteered us to take her and her walker back to the ranch. The #2 cheap MAF stared out with zeroed LTFTs, but 9-10 on the STFTs??? But within 10 miles, the LTFTs climbed to 5-7, and the STFTs were balancing them there.

After dropping the wife and granny at the ranch, I drove back home, observing fuel trims, and O2 graphs, and consistently normal grams per second readings. I'll leave this MAF in place for awhile.

And, despite what several of you have intimated, a bad Siemens VDO MAF isn't as good as a $20 MAF from Amazon.

So, until I take the time to replace all my sensors, vacuum lines & fittings, go through the DISA and idle valve work again ( and maybe send out the DME just to have it checked out), then I'm still in the same position as I've been in for 3 years. "A lean condition without a cause"...catchy title for a car movie, don't you think?

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[workingonit]

I did have a good experience driving tonight, nevertheless.

As I stated, I'd never before driven my X5 at night, so I wondered how well the old halogens would light up the road. Much clearer and better aimed than on my other halogen-lit vehicles, I'd say.

I don't see the need for xenon's, HIDs, or LEDs. If I (with my old eyes) can see this well at night with halogens, then I'd have to wear shades with brighter headlights!

Also, the orange dash lighting is great! I prefer it to the green (Chevys, GMCs, Olds, Dodges, even Volvos and VWs) instrument panel lighting, and even the red lighting on the two Pontiacs I'd owned. Nice.

Another positive: tonight being the most highway miles I've driven in the X, both in total miles, and definitely in miles driven for one trip, I observed higher mpg readings than ever before. Despite the first, middle , and last sections of my 140 mile trip being in heavy stop and go traffic (even at night, I can't seem to be free if it), I still got 19.1 mpg overall. So, though the fuel trims problem remains, and I wasn't able to drive a constant speed (20 to 85 mph), I'm happy with the latest mpg figures.

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[Happy]

Originally Posted by workingonit

And, despite what several of you have intimated, a bad Siemens VDO MAF isn't as good as a $20 MAF from Amazon.

My implication will always be, a brand new genuine MAF is going to be 99.9% better that any of the above. LoL..

Glad to here the X is running good though! It will get sorted at some point. Sometimes it just takes a bit, believe me I’ve been through it all with my M54 powered E53.


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

[workingonit]

I'm still considering adding a homemade, on-the-fly "MAF sensor reset switch", simply because I need an interim fix for the phantom vacuum leak, fuel system shortfalls, or simply a MAF problem (choose one, or all, or none of the above) problem, especialy now that emission-inspection time is coming soon. And, after using the old, bad, Siemens sensor, and seeing how fast it can set a SES light, I don't want to have another such situation pop-up, when I'm going to the inspection station.

But, even if I install the reset switch, it won't do anything to actually reduce the effects of the "lean condition" that my MAF sensors all show to be present. So, I've been looking for a way to adjust the air-fuel ratio manually, tricking the DME. I found this on the internet today:



It was designed for use with a HHO device (hydrogen/oxygen adder/converter) which I suppose is like a power adder. As I've read it, the device shown can be used without the HHO being activated, but running on stock engine power alone. There are three wires, like the analog MAF sensor has, so instead of using a reset switch, I might could adjust the MAF to tell the DME what I'd like it to see.

I like remote devices for dashboard tuning anyway, having used ones that enabled me to adjust timing, launch and top-end rpms, and even nitrous horsepower injection jet sizes, all from my dashboard (while drag-racing). I'm sure that this device could be used to adjust the MAF sensor otput signal, to actually convince the DME to change the fuel delivery rate, away from a lean condition. Done a little bit at a time, so as not to go full lean or full rich, with the bad consequences that might follow.

To make my reset switch, I'll be ordering about $35 of parts, and as soon as my limited "car" budget recovers (from a recent auxiliary fan replacement $200, three vehicles inspected/registered $275-290, all in a month), I'll probably order this MAF tuner device from Europe. I presume there will be instructions for its' use.

[workingonit]

Originally Posted by BimmerBreaker

Unplugging the MAF triggers a CEL - resetting the CEL resets the readiness monitors. You need those readiness monitors to be set in order to pass emissions....

No, unplugging the MAF didn't trigger a CEL on my M54, but using the faulty Siemens MAF did, after about 5 miles. It set codes P0102, P0171, and P0174, triggerring the MIL (SES, CEL) light, upon which time I put in the second cheap MAF, for my return trip home. I cleared the MIL/SES/CEL, and watched the Torque Pro display during the 70 mile return trip, to see if the fuel trims would start stabilizing at highway speeds.

LTFTs started at zero, as expected, but during heavy Saturday night traffic, they rose as high as 9, with the STFTs trying to bring them down. Only when I hit the open road for 20+ miles did they fall, to as low as 4-5, but once again entering into heavy stop & go traffic, they rose to 6-7 (nowhere near the ridiculously high numbers given by using the Siemens MAF).

So, just now, after reading your comment, I went outside and snapped a few screenshots of my 8" tablet that I use for the Torque Pro app. Sorry about forgetting to turn off the flash...
high LTFTs, but witin limits
MAF code was set on trip home, but not the lean codes
showing emissions readiness monitor, before clearing the code
after I cleared the single code
yes, now I'll have to drive some more to be ready for testing

I agree with you, that I'm going off on tangents, with work-arounds and such, but I've pretty much exhausted my diagnostics ability (and I don't have the $$$ to make a dealer or Indy richer, with no guarantee of a true fix), so after running out of options, I'm going to modify the system (either in Star Trek's "Kobayashi Maru situation" fashion, or like Steve McQueen did in real life, trying fringe medicine to cure his cancer). Unless I fry the DME, what can I lose?

[workingonit]

Originally Posted by Clavurion

Connector X6965 is a soldering point where all those voltage supply lines are bundled together. It's located in E-box where DME also lives. That would be a good place to cut and make the wiring for the switch. The wiring can be routed thru E-box vent route thru firewall. Perhaps it would be wise to put a separate smaller like 5A fuse near the switch so if the line happens to ground on the chassis that fuse would be easier to replace than the one on E-box fuse pack.



https://bmwteka.com/wds/en/e53/493a47c7#

I don't intend to go anywhere near the DME, E-box, or any splice/junction/connection in or outside the E-box, either. Too many chances to screw up something vital.

My preferred connection would be further down the + voltage line, past X6965, and having put the pigtail inline (as a sacrificial extension), I'll be able to cut the + wire just before the wire enters into the MAF sensor at X6207, Pin 3. Actually I'll put a 5 amp fuse there, then run a two-wire extension to the on/off switch inside the truck. That way, only the + wire on the pigtail ever gets touched, far away from the DME.



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[workingonit]

Originally Posted by BimmerBreaker

It's also possible you may just have a weird DME fault causing this - the MS43 has a barometric sensor on the DME board and I've seen similar issues with an MS45 with a barometric sensor problem. The sensor didn't fail - so no code, but it was faulty - the result of this was the erroneous data fed to the DME messed up the fuel trims. The car I was working on would throw consistent O2 sensor codes after enough driving....

I read about problems with the barometric sensor in the DME causing problems (on E46, E90, E92s), but no solutions or fixes other than a repaired DME.

And Happy, I've looked carefully at the wiring all the way back to the DME, and nothing looks worn or torn. The DME still looks untouched.

So, I don't want to be the guy who opens up a perfectly sealed and working DME, if nothing is amiss inside, so I'll try my Android app "BimmerTool" to see if it will give me data on the baro pressure ( it has a PID on the live data list for it). My other Android apps, Torque Pro and OBDLink, have a similar PID, but don't show data.

I haven't seen anything on my Foxwell about baro pressure, and I'm so far out of practice using Inpa, that I will have to learn all over how to use it, that I might not be able to verify if there's a baro pressure problem causing the MAF to read incorrectly. Also, the O2 readings look good, no matter what MAF sensor I'm using (wouldn't they show a baro problem as well?).



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[workingonit]

I already bought the parts I needed for the on/off MAF reset switch, and was about to assemble them for installation, then reconsidered.

I will wait until after the state inspection (safety & emissions...my '01 is two years away from not having to get the sniffer test, anymore) before I do any experimental work on the MAF system. I'll use Liqui Moly Catalytic System Clean 7110 and Premium gas to prep the fuel system (not the Jectron 2007 that I usually use), drive about 100 highway miles to make sure that all the emission monitors get set, and drive directly to my usual inspection station (before the fuel trims go wacky again). Then, I can experiment.

Researching and reading. I read a lot this past week, seeing how people custom-tune their MAFs, MAPs, and even the old mechanical Air-Flow monitors, from the 80's 'til now, Chevys-Toyotas-Ferraris, all of them. There's actually less info concerning BMWs than most other makes, of course, since BMW wants it that way.

I wish I had been trained in electronics, as most of what I read was basically Greek to me (I might've understood Greek better!). But, I did find a possible way to make minor tweaks to the MAF signal that tells the DME what the airflow is, by tricking the system, using a device to adjust the heated element component in my MAF sensor, without adding resistors or using a custom air intake tube.

If I was to lower the temperature of the hot-film (similar to the old type hot-wire) heating element, it would make the MAF act like there was more airflow than there actually was, then the resulting signal generated and sent to the DME would naturally enrichen the mixture without having a false lean fuel trim reading do the same.

I originally thought my lean fuel trims (triggerring P0171, P0174, and eventually a CEL) were caused by my Siemens-VDO MAF under-reporting airflow. I still think it does. The cheap $20-23 Amazon MAFs I've been using for two years, give better airflow readings, but not perfect. So, my idea here is to further trick the system, by using another cheap device (a "Buck-Boost" converter), to fool the DME into thinking that airflow is greater than in actuality. And maybe quit trying to set lean codes in the process.

I previously used a diagram (in post #1) that was wrong, but found the correct diagram for my '01. It shows that if I would insert a step-up/step-down voltage control ("Buck-Boost" converter) in the 12v wire just before it enters the MAF, then I could use it to either raise the temperature of the hot-film heating element (which would cause a lean signal to be sent), or preferably, in my case, lower the temperature (which would cause a rich signal to be sent).


I see that there are all sorts of circuit protection in the units I've investigated, so no damage to the circuits upstream nor downstream of the device should occur. Of course, I'd also use a fuse ahead of the device, anyway. If, perchance, one of my three MAFs were to fail, then I'd have the excuse to try a mid-grade MAF (from Hella, Bremi, Pierburg, or even Delphi...I'm not ready to buy a Siemens VDO, until I fix the phantom problem first).

I am currently looking at three converters, from $25-34, that I might try. I have no idea what actual amperage/wattage rating is needed, but I've wasted money before...trial and error is often expensive. Of course, I'm watching many videos on how to set them up, but it'll take me awhile to get the gist, if ever.

[X5chemist]

Can you graph O2 readings? All four at the same time?

Short of disconnecting the fuel line and using carb cleaner to clean injectors, try some of this stuff. https://www.atschemicals.com/505-pour-ins/
Use only as stand alone treatment. It shouldn't be mixed with other additives.

[workingonit]

Originally Posted by X5chemist

Can you graph O2 readings? All four at the same time?

Short of disconnecting the fuel line and using carb cleaner to clean injectors, try some of this stuff. https://www.atschemicals.com/505-pour-ins/
Use only as stand alone treatment. It shouldn't be mixed with other additives.

I use Torque Pro on an 8" tablet, attached to my dash (via a APPS2Car Universal Car Mount [2 in 1] CD Slot Tablet Car Mount) whenever I run the engine, so I can watch the vitals as it runs. I started using Torque Pro as soon as I discovered that the BMW temp gauge was a "cold-correct-too late" gauge, and I wanted to know exactly what the coolant temp was, since I was replacing the failing mechanical fan with an electric fan.

A couple of months later, when I got a CEL and P0171 & P0174 codes, I added the MAF gm/s PID to it, and the fuel trims for both banks, and I observe them as I drive.

I have a main screen, with the most used data displayed, as well as 3 other screens with other data (emissions readiness, other assorted live data, and one for O2 sensors). I can easily flip from one screen to another, if I wish to know more.

As I said. in an earlier post, my O2 sensors were behaving normally, even when the Siemens VDO sensor was badly mis-behaving, but I didn't take a screenshot. I can also graph the O2 sensors, but haven't done so in a long time, but I have an old composite graph I posted 2.5 years ago, in this thread https://xoutpost.com/bmw-sav-forums/...s-present.html

As for the suggested additives: I've been using Liqui Moly Jectron 2007 Fuel Injection Cleaner (perhaps too often?) for three years, sometimes in conjunction with STA-BIL 360 Protection Ethanol Treatment & Fuel Stabilizer (if I fill-up and don't expect to drive the X for a month, to keep the Ethanol problems at bay); I've recently backed-off on the two additives, to make ready to use a stronger chemical cleaner, to perhaps clean the catalytic converters a bit.

I was going to get Cataclean, but decided to give Liqui Moly a shot at doing the job, first, so I bought Liqui Moly Catalytic System Clean 7110, which might help (though the description doesn't specifically say it will clean cats). But, my Bosch O2 sensors (with under 5000 miles on all 4) don't seem to be having problems, and the engine runs great...so maybe my Bremi injectors (also under 5k miles) and cats are OK, and nothing is dirty enough for stronger cleaning additives?