P0171 P0174 Check Engine Light CEL
 

INTRO:
Month ago I got a CEL for these codes ago. Reset the codes to see if they would come back.
They came back just recently so I added a bottle of Red Line S-1 to my full tank and drove it. The CEL came back on again after some time.
Now every time I reset the CEL light, it comes back on after 20 mins of driving.

DIAG:
Checked the intake boot etc for leaks, didn't find any.
Checked for leaks around the DISA (mine is fairly new) - none.
Checked for leaks around the intake gasket, didn't find any.
Checked for leaks at fuel filter, found a cracked vent hose. Replaced. Still throwing CEL.
CCV is fairly new, within last couple years.
Pulled oil cap, engine gets rough (as expected)

FUEL PRESSURE: ***
Fuel pressure at running idle - 55 psi (ABOVE max spec of 46.4)
Fuel pressure, jumped pump (car not running) - 54 psi (at max spec)
Fuel pressure drop after 20 mins shut down - 4 psi drop (within spec)

I got a lotta miles - 255k. Not sure I ever replaced the fuel filter. Might be the culprit. Do we agree? Or could there be something else causing the high fuel pressure? Or is this high fuel pressure in response to the lean condition?


***
10/31 - I got a new fuel pressure gauge: The new gauge is reading the following:

Fuel pressure at running idle - 49 psi (ABOVE max spec of 46.4)
Fuel pressure, jumped pump (car not running) - 49 psi

SCANNER:

STFT B1 19.5%
STFT B2 21.1%

O2 B1S1 0.005v
O2 B1S2 0.94v

STFT B1S1 19.5%
STFT B1S2 99.2%

O2 B2S1 0.005v
O2 B2S2 0.935v

STFT B2S1 21.1%
STFT B2S2 99.2%

Do you have the long-term fuel trims?

Your short-term trims are certainly quite high positive, but ST trims are often less informative..

Based on ST trims alone, I would suggest you have a proper smoke test, NOT one with a cigar and a fluid pump. The brake booster is one area folks miss when doing a smoke test..

your fuel pressure is 1-3 psi high, but I think that might be attributable to your tester.
Your fuel trims are positive which says the DME is adding fuel to the air/fuel ratio, So if it was over-fueling (and I have experienced this), The DME would reduce fuel to the mixture.

Long term fuel trim bank 1 - 7.8%
Long term fuel trim bank 2 - 6.3%

Thanks for helping. Sounds like I need to purchase a proper smoke machine.

One thing I noticed is the numbers seem fine when the car first starts up but after driving like 20 mins and coming to a stop everything goes bad - o2 pegged lean and STFT skyrocket.

This is right after start up
https://share.icloud.com/photos/0dd5...FaRz4-19Fy6NcQ

Why would that happen?

Smoke test but you can also use an unlit propane torch to spray near suspect areas while watching O₂ feedback real-time. BB is a giant diaphragm so can easily be a bug vacuum leak. You can pinch off the hose to test while watching O₂ or STFT.

Also; FPR uses vacuum hose for pressure reference to intake. You said that was replaced if that's plugged can cause fuel pressure problems.

Odd to see high fuel pressure and also high positive trims.

Can also be MAF sensor reporting wrong air value. The baseline calculation based on MAF the car adjusts fuel after the fact.

The error you're getting says there is unmetered air but it's the identical affect of MAF reporting inaccurate=low quantity.

I've tried spraying carb cleaner all over the place before and after the engine has heated up, but I have not observed a change in engine idle.

If it was the MAF, wouldn't it show lean right after start up? Mine is showing fine after start up, but pegs lean after 20 mins of warm up.

P0171 P0174 Check Engine Light CEL
 

The car runs rich when cold. I will also allow wider swings of fuel trim without an error.

Similar fuel trim problem, for over two years
 

I've been fighting my high fuel trims for two years, now, and have never found a vacuum leak (smoke tested 3x, carb cleaner test 4x, visual inspections as well).The O2 readings have always been good.

My fuel pressure tested barely 50psi, but only had two misfire errors over a year back, and none since (the engine starts and runs smooth as silk), so it's probably not the fuel supply. Rebuilt the DISA, replaced the filler cap & gasket (the only possible leaks I ever found), and I'm fairly sure the CCV is OK (23+ psi vacuum while running, according to Torque Pro, no sign of Mayo).

I cleaned my original Siemens MAF, and still had very high fuel trims, then tried a $20 MAF from Amazon, and the fuel trims got much better (the MAF readings were much higher), and that's the way I operate it now...having never completely eliminated the high trims. I also bought a second $20 MAF (Amazon owed me a refund on another purchase), and I now have three onboard. My conclusion, at that time, was that the Siemens MAF was underreporting, but there's got to be something else contributing to the lean condition.

I haven't driven my X5 since July, and only ran static tests in the driveway this summer, so when I had a Dr's appointment today, I put two bottles of Liqui Moly Jectron Fuel Injection Cleaner into the tank (previously filled in July), and took a chance on the state emissions test a few days early (due by 10-31), since I was out and about. It passed, despite LTFT's between 7-11, and the short terms trying to balance them.

I should've driven the X5 a few hundred highway miles with the cleaner in the tank, and the trims would've been better, I'm sure (my mpg goes up considerably, and the fuel trims go down as well, on the very few occasions where I give it the old Italian tune-up).

My new take on the lean condition is my injectors aren't flowing very freely. I have no idea how old they are, and/or their maintenance history. I have had good luck using Lucas Injector cleaner on my GM cars over the years, but I have no experience using Liqui Moly, but I'll find out. Now that it's getting cooler outside, I'll start driving and testing the X5 some more...I'm determined to find the root cause of the high fuel trims before the next inspection in October 2024. Maybe using some Cataclean is in my future, as well.

Update: bought a smoke machine.

Smoke tested:
Intake - no leaks
Vacuum booster - no leaks
Exhaust - no leaks

Then I drove it about 10 miles and was able to reproduce the lean condition.

This time however I noticed that bank 1 was lean while bank 2 was still looking ok.
Drove it some more and bank 2 started acting up again so both banks were now lean.

Drive it back home and did a smoke test while everything was good and hot.
Still no leaks anywhere.

Does the car go into closed loop one bank at a time?
If it goes to closed loop on both banks at once, sounds like it can’t be the fuel filter/regulator.

It may either be the fuel injectors or maybe the oxygen sensors.

Do you have a tool to check your air flow. should be around 4.1-4.6g/s around 600 -700rpms.

E53 uses millisecond timing of injectors to determine fuel metering.

The math only works correctly if the fuel pressure is 50.0 psi from my understanding.

I think all non diesel e53 use that same baseline pressure.

The e53 doesn't meausure fuel pressure it just assumes it's correct.

You said the pressure measured high but was that just at idle? What's the fuel pressure under load?

Low fuel pressure will give the same results as MAF reporting low air or unmetered air leak. It also may affect one bank before the other since the fuel is supplied on one end.

Did you mention which engine? I missed that important detail.

In my experience the fuel pressure will be rock stable at idle and dip a little under throttle but stay at the slightly lower pressure not shake.

Any flutter in the needle means FPR not regulating correctly.

I do. Keep in mind this is a x5 3.0...

It's around 3.5 @700 RPM

The fuel pressure readings I gave earlier were at idle. Full pressure under load was similar to what you describe.

This is the 3.0 engine.

P0171 P0174 Check Engine Light CEL
 

Theory; MAF reading low:

This should mean that the O₂ sensors will add an equivalent percent of fuel to make up for the error.

STFT ≈20%

3.5 MAF times 1.2*3.4=4.08

Add 7% long term 4.08*1.07=4.366

4.37 is right in line with a baseline error free engine.

Prime suspect: MAF.

You can get a $20 test case off Amazon I would buy a Siemens OE MAF once I was convinced.

(FYI; when my m54 was about 190,000 miles I did just that when my fuel trims were climbing steadily over time)

Not sure if airflow readings are affected but I would def check the condition of the air intake filter.

So are you saying the MAF reading should be around 4.37 at idle?

JPuma did the measurement and yep.

4.35 is the center of the range.

This was a recent discovery for me. I had a bad maf wire for a long while. tried two MAF's to no avail. my problem was intermittent but didn't notice until I started monitoring airflow. Finally replaced the wire and its been stable since. I may have killed my Cat's because of this.

Cats can recover somewhat if just abused


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was my Siemens MAF actually good, and not underreporting as I had believed?
 

I have a comparison from the day I switched from my stock Siemens MAF, to using the $20 ($23 then) Amazon MAF. First is the Siemens' reading, then the initial reading of the cheap MAF, and a third reading a little later on that day. I didn't zero-out my fuel trims, as I was primarily interested in the MAF readings.
Attachment 83641

Per JPuma and andrewwynn, the Siemens reading was already pretty good, but the cheap MAF readings were actually a bit high (but that kept the fuel trims from setting lean codes). Since that day, the lowest idle MAF reading I've seen was 4.1 g/s, and the highest was 6.1 g/s. I'm still hunting for a vacuum leak.

That sounds promising.

The OE is really the best bet, but I do think there is something else going on why your fuel trims are so high.

Logicality just the MAF. The reading reported is almost exactly as low as expected by the % fuel trim error.

Ok I have a cheap Amazon MAF on the way. Should be here tomorrow.

I’m going to check that MAF wire.

Whatever is going on, CEL is definitely dependent on the car being warmed up as it triggers after driving.

You have the part number for the MAF wire?

I actually just purchased a wire from Autozone.

Duralast / Turn Signal Light Connector (no idea why it's listed as this lol)
Part Number:
789
https://www.autozone.com/electrical-...789/884233_0_0


I was going to buy parts from the FCP Euro, but I didn't want to wait. plus you have to crimp pins on the wire.

https://www.fcpeuro.com/products/bmw...or-12521427222

https://www.fcpeuro.com/products/bmw...lk-12521427612

Can a MAF give a good reading at idle but then not really respond well as more air is introduced, showing less air that is coming in?

Took my car for a ride last night after having my fuel filter/pressure regulator replaced.

What I have been seeing after the wire repair is barely any adjustments in LTFT when I am mostly idle or doing local driving.

When on highway, steady driving. LTFT goes to 2.13-3.19 ish. Bank 1 is lower than bank two. But after the fuel filter replacement, the LTFT has been even in both banks. but still around 2.13-3.0. when i get off highway, the LTFT starts to drop.

This could be normal but I am not sure. I'm also planning on either replacing my fuel injectors or cleaning. I may just replace as they are original from 2001 and I am trying to overhaul as much as I can.

Shouldn’t you be monitoring short term fuel trims instead?

I do, but values are normal when idle, just bouncing up and down within range. As I understand it, LTFT is the result of where your STFT is averaging out, so LTFT adjusts for that.

Not sure if you’ve measured continuity in these wires but this is what I got:

Wires 1 & 2: 4.669 kOhms
Wires 2 & 3: 10.58 kOhms
Wires 1 & 3: 3.763 kOhms

Is that the measurement off the MAF?


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I havent, but I think the issue there is just worn pins not making good conductivity, or possibly the crimped wire strands in the insulated wire breaking over wear and tear. A video I watched of one user sources his problem to bad connectivity in the connection plugged into the DME. I've check and cleaning mine on that side too.

After racebmwm3 posted the stats of each MAF he tried I decided to circle back on the used OE MAF I bought to retest since replacing the wire seems to fix some issues for me. I had a newly purchased MAF from VDO in since 2019, but before that I bought a used Siemens MAF because I broke my original one (oops). I was skeptical the used OE MAF wasn't working right because of wire issue.

My fuel trims are amazing now after the normal test drive I take. My car doesn't vibrate as much which is another issue I have. Can be a placebo to me so ill keep an eye on that. Was planning on replacing my motor mounts because of this vibration.

Attachment 83650

Up next is a piston soaking, just waiting for ACDelco additive. Going to check my pressure before and after. Will make a new post for that soon.

Measurement on the harness. But you’re right, I should probably measure the MAF as well.

Update:
Got the Amazon MAF and installed, but doesn't seem to have changed the situation. New MAF reading similar to old MAF.

I still cannot get decent fuel trims. I disconnected the battery to try to reset everything, but I am still not getting proper fuel trims. Things mostly fluctuate but have never been within the right ranges.

The last time I tried testing, I was getting STFT Bank 2, then both STFT pegged at exactly 15.60, then they dropped to both negative after some time.

Still throwing CEL.

I am totally stumped at this issue. Not sure what to try next.

If MAF looks good, check your fuel pressure, I think you mentioned you did. how's injectors?

What is your LTFT at idle after warming up. Do you have a tool to clear your adaptations? when you pulled your battery and tried again did LTFT clear and start at 0.0?


Attachment 83659

No idea how to tell if the injectors are bad or not. Fuel pressure was tested in Post #1

I pulled the battery, shouldn't that clear everything?

I did clear everything with the ODBII tool as well, or I thought I did.

LTFT's after some testing were 11.70
STFT's were running all negative

https://share.icloud.com/photos/0ffZ...1uBE86opDALUBA

I don't think pulling the battery will clear the adaptations. I use INPA. Your LTFT is suggesting you have a big air leak or bad gas flow. Driving or letting it run should adjust it over time if the MAF was an issue, but it doesn't look like changing the MAF had an effect.

https://www.bimmerfest.com/threads/a...-values.39418/

Did you check the back the of the intake manifold, there is a rubber going over a vacuum port. Then a small hose going to secondary air. How's the rubber boot and the little arm attached to it? How about CCV? or the vent hoses going to CCV? Top one from valve cover?

I smoke tested multiple times. Didn’t see anything leaking anywhere. Rubber nipple under back of intake is fine. CCV is good. Replaced whole system couple years ago with updated version. I’m not sure what you’re referring to regarding small hose, rubber boot and little arm. Hmmm

P0171 P0174 Check Engine Light CEL
 

Smoke test was done on intake. I think also on valve cover (If not do so).

A very sneaky vacuum leak is where the oil dipstick tube goes into the engine block.

My gut is saying that something is amiss with FPR. It uses vacuum from intake as feedback loop to drop actual fuel pressure when there's high vacuum. If that's not working properly the fuel pressure may drop too much. Also I've never seen over 50.5 at idle so the numbers you reported seem way too high.

That said, if the fuel pressure is high and your still are getting positives fuel trim it suggests the injectors.

You can remove and clean old school injectors. Some shops will do this service. The cleaning machine will have clear walls to see the injector spray.

Yep I smoked tested everything. No smoke coming from anywhere. Removing the oil cap during the test released pressure and smoke so I know I was doing something right. I pulled the dipstick when I was smoke testing and I could hear the pressure release up thru the oil. No smoke was escaping anywhere. CCV is relatively new. All good hoses. No leaks.

I’ve just figured out how to reset adaptations on my scanner. Resetting things brought the LTFT to 0. STFT started high but are coming down as I sit here and idle.

https://share.icloud.com/photos/039L...1b7Mu4Ur_00DNw

STFT coming down into range while sitting here at idle after adaptation reset:

https://share.icloud.com/photos/0b7t...NbTNJ9JnaZHiow

Andrewwynn is again spouting a bunch of BS. The fuel pressure regulator line is vented to the intake boot on the E53 M54, not attached to manifold vacuum. At most it might compensate for a plugged air filter. If you had it attached to manifold vacuum it would drop your fuel pressure proportional to engine vacuum and cause your engine to run lean with the fuel trim trying to compensate ;) 54-55 PSI engine/pump running sounds right to me but it's been a while so I might check again if I get a chance. It's pretty hard to get too much fuel pressure unless you put pressure on the regulator diaphragm.

I get it.

So what do you think my issue is?

Update:

So after reseting my adaptations and starting the car up...

STFTs start high 15+
LTFTs at 0

During driving the car for 10-15 mins, the STFTs are slowly dropping (going up and down) in unison until they get around -8

At some point in time during this trip, the LTFTs went to 11.7.

(New) MAF sensor is < 3 g/s at idle (700RPM)

All during this trip, the O2 sensor output voltage on Bank 1 and 2 is looking proper - cycling between 0 and 1 volts - I have not seen this happen to date. Usually the voltage is pegged (lean) at 0 volts (or close to it).

The long term trim (block learn) is the one that matters, it's normal for the short term trim (integrator) to go up and down, if it can't keep up then it bumps the long term a notch and tries again. The o2 sensor should be cycling so that is good but if that is different after changing the MAF then you gotta wonder. The only way to really rule out the MAF is to replace it with a known good one. Puma is right about resetting the adaptations but in cases like this you can also just watch to see what changes starting from where you left off instead of re-setting and starting over. Also triple check the MAF connector as has been pointed out, they get yanked on a lot so you might have something going on there.

AND as has been pointed out CHECK FOR VACUUM/AIR LEAKS.

O2’s cycled to some extent before but would eventually peg lean before new MAF change.
Before resetting the adaptations and after replacing the MAF, I wasn’t getting better results so I reset the adaptations as a next step.
Can’t find any leaks anywhere. Smoked tested multiple times.
MAF wire seems fine. Manipulated it while watching data but couldn’t get any change to occur.

The most likely thing is still an air leak(s) somewhere. You say that it's expected that the engine runs rough with the oil cap off but it for sure is going to run rough if the CCV valve is shot so that isn't ruled out. I no longer have the CCV so I can't speak to what the crankcase vacuum should be if it is working correctly. With that many miles ( I have 450k kms) there is probably more than one thing going on as well. I know both my rear main seal and pan gasket are leaking air into the crankcase, my injectors are leaky, and my cats are probably not the greatest so I'm always on the edge of having the CEL come on/off. I can get my light out with engine oil stop leak, a can of cat cleaner, or boosting the fuel pressure a bit but none of that is consistent and that isn't really a fix.

If you haven't checked your fuel pressure driving under load you should do that as well.

Update:
Got a new fuel pressure test gauge. The new gauge is reading 49psi at idle. Still a little high per Bentley. Other sources I see online seem to think 49-50 psi is fine at idle.

With the new gauge, I did some more tests with the gauge attached to the fuel rail:

- Per @80stech, with the gauge secured on the windshield, I drove the car. The fuel pressure remained pretty constant at 49psi unless I blipped the throttle, which would cause the fuel pressure to drop a little bit temporarily.

- I removed the fuel pressure regulator "vacuum" line from the intake boot. The fuel pressure did NOT increase. Per Bentley, the fuel pressure is supposed to increase by 6-10 psi when doing this. It's not entirely clear but it seems as though Bentley wants you to remove the vacuum line AT the fuel filter. I removed the line at the intake boot, which I would think would produce the same result. Bentley says to replace the fuel filter/regulator if the pressure does not increase.

I have a fuel filter/regulator on order.

The regulator/fuel system doesn't work as it shows in the Bentley manual, BMW probably updated it and Bentley just carried forward the old info. It doesn't matter where you disconnect the vacuum line for the regulator it is not going to change the fuel pressure because the line is only being vented to the boot and isn't tied to engine vacuum. BMW likely decided not to use the vacuum portion of the regulator because the processors in the DME where getting fast enough to keep up without it. Some of the repair info didn't keep up though ;)

I was wondering if this was an example of that. Very frustrating.

Well, I likely need a new fuel filter anyway, I don't recall the last time this was changed. I need to rule it out as well.

Yep, it likely isn't your problem but it's not wasted money either.

The whole fuel pressure checking is a often a problem with DIYers trying to get away with poor quality gauges and fittings not fitting properly.

+ make sure the bit of hose at the regulator is still in good shape as well, that's a bit of unmeasured air if it is leaking.

Well, I went to use the old gauge today and the adapter that attaches to the fuel rail was leaking. The o-ring was bad. Went to replace the o-ring and the center pin fell into oblivion. So I had to get a new kit as I could not find the adapter around town.

I had replaced that small hose piece last time I was under the car during this process. It was dry rotted and upon trying to get it off, it crumbled. So I'm good there. Thanks for checking.

Haha so I had a chance to check my fuel pressures and I think I am just going to add to the confusion! I have a 35 year old snap on gauge that (I am pretty sure reads low) says 43 and 47 PSI and I have a home built digital gauge (arduino based with oled screen showing min, max, current and average) that I built a couple of years ago that says 49 and 55.5 PSI. I never did check the calibration on the digital gauge and was going to check it against my Fluke pressure adapter (also about 35 years old) but I remember that something was wacky about the switch on the Fluke and never did get around to fixing that or going any further with checking the home built gauge.

Update:

Replaced the following over the past 2 days:
- fuel filter/regulator
- 2 precat oxygen sensors
- spark plugs

Tested car on scanner in between each change.

- Old fuel filter was full of the typical black crud coming out of the inlet, so it was due to be replaced anyway. Fuel pressure after filter change has dropped to around 47 psi at idle, I assume I can attribute this to the new filter having more free flow.

- Not sure oxygen sensors were ever replaced, so cross that off the list.

- Lastly, spark plugs were pretty bad as well. Replaced them.

After spark plug change, Bank 1 and Bank 2 STFT are closer together. Not much delta.

What I am seeing on the scans is somewhat the same as last time.
STFT starts out high (15+) and creeps down low over time (-15+). When driving STFT is above 0 and very high. When idling, it goes negative. And if you sit for idle long enough it will continue to creep down negatively.

So I am still getting STFT too high/low, out of normal range.

Attachment 83716

Again, the long term trim is going to tell the story. If things changed (o2 sensors started toggling when they didn't with the old MAF) after changing the MAF then it's likely the old one was no good and I wouldn't put much faith in the $20 one. "just adds to the soup" as Clavurion would say! ;)

If your pump running fuel pressure really did drop you might have a look at the syphon jet o-ring.

P0171 P0174 Check Engine Light CEL
 

https://www.motor.com/magazine-summa...agnostic-tool/

A very good article.

Suggesting a stuck open purge valve.

If the hose is soft enough you can pinch it shut with a couple pieces of wood and a locking pliers (or pick up the hose pinching pliers made for this job)

Purge valve or dirty / sticky injector.

Have you run injector cleaner? This model engine uses math to estimate the amount of gas per intake stroke. If the fuel pressure is off that's one way for the math to be wrong but when dirty the injectors will shoot less fuel thank designed so fuel trims will have to rise to compensate.

Since there's no feedback loop for How much actually comes out except O₂ sensor and the ECU assumes the injectors are perfect out blames the intake air.

One other test for stuck open valve: I wonder if there's a path to the fuel tank from the purge line a smoke test would feed back out the fuel fill. I can't remember the exact plumbing out might only go into the charcoal canister.

The best way to check the purge valve is to pull it off.

I remember your old posts showing the gas tank and all the plumbing. I have a small evap leak I cant find and your posts in the past were helpful.

https://youtu.be/jipBVzO1P7A?si=5aosIDZUQk_z6DhR

It's for e46 so the intake air box is different but speed exactly where to find the purge valve.

A stuck open purge valve should throw an error and smoke should have found a bad hose.

https://youtu.be/HiPlKLP9E6I?si=W8AZKhpLq-b6OC8q

Testing the purge valve.

injector tests (with injectors still installed on engine)?
 

I'm wondering if my injectors are causing my lean codes/high fuel trim numbers. since I haven't yet found another cause, after two years of searching. I have no idea how old they are , what brand are they, or what condition they're in, but I've only had one or two misfires in two years, zero start or run problems, and other than high fuel trims, nothing to complain about.

Perhaps, before I do my forthcoming hands-on vacuum line examination and/or replacement, maybe I could test the injectors thru a diagnostic app, or with my Foxwell?

The injectors should be clean (and getting cleaner), because I've fed plenty of additives thru them, even though I don't drive the X5 much.

Just prior to taking the X5 for emissions/safety inspection last month (it passed!), I put in two cans of Liqui Moly 2007 Jectron Gasoline Fuel Injection Cleaner and drove it 30 miles (probably didn't do anything that fast, but it can't hurt).

I have already been using Lucas Oil 10576 Safeguard Ethanol Fuel Conditioner with Stabilizers every second or third fill-up, and Lucas Oil 10013 Fuel Treatment (with injector cleaners) maybe once every year (I used it regularly on all my vehicles monthly, until I recently ran the 1-gallon jug empty).

And, I always get top-tier gas (premium) at either QuikTrip or Shell, so those brands already have some injector cleaners in their formulation.

Back to possible testing: is there a test on my Foxwell NT510 Elite, that might pinpoint injector problems? like balance, or spray pulse timing, or ?? Or, on my BimmerTool Android app, I've seen an injector test listed (on their website, it says it will read injectors adjustments and
read actual and expected values for air mass, intake manifold pressure, fuel pressure, but I never tried it, as I was having problems getting the app to run properly with my OBD interfaces (both a bluetooth dongle, and a USB/OTG/FTDI cable, at various times, on various Android devices). That was over a year ago, so maybe I'll try again? I don't recall any injector testing ability on my other Android apps (Torque Pro or OBDLink).

Then there's my Windows 11, ARM64-based laptop, which I've seldom tried in my X. I installed INPA (and ISTA+, but it won't open, due to low memory), and OBDWiz on it; I've barely tested functionality of the INPA, and never tried the OBDWiz (basically a more detailed vesion of the Android OBDLink app, but for Windows), so I guess I'll hook-up my 10-amp charger/maintainer again (to keep from repeating the problems I had while testing just on battery power alone), and see what I can find.

Has anyone done injector diagnosis using any of the above methods?

Yes, I used Red Line S-1 at the beginning of this thread (post 1)

I've been going through the article. Great find!

You may be onto something here. With the car off, I disconnected the purge valve from the harness and applied 12v direct power like the guy did in the video. First 1-2 times I didn't hear a click, then next couple of times I heard the "click". Hoses look fine. The purge line to the gas tank runs under/next to the airbox, by the way.

Then I started the car and scanned things again. This is the first time I noticed the STFTs within range. Check out the first part of the scan attached.

Attachment 83717

Then I drive the car for a couple minutes and parked. The elevates STFTs stared to slowly decrease.

Drove the car back home and parked again. The elevates STFTs started to decrease again.

At this stage, I tried clamped the purge valve return line to the tank but I could not get a change in the STFTs.

I thought about removing and cleaning the valve, but at this point, I don't trust it. Going to order a new purge valve tonight.

I will be as happy as you if the purge valve was the cause.

You did what you could with injector cleaning. Usually if they are dirty enough to cause fuel trim you'll get misfires galore so I don't think it's injectors.

My foxwell only tests the injectors individually either ON/OFF or pulse for 20 secs. I am not aware of any other tests. I have an NT530.

Does it read all the codes? There should have been a code for the purge valve if that was the problem.

There was not a CEL for the purge valve.

Update:

We are getting closer.

Today, I got a new VDO/Continental MAF installed. I immediately saw an increase in the new MAF signal vs. the Chinese MAF vs. My original BMW "old' MAF. Now, the MAF shows ~4 g/s at idle vs 2.x-3.x before. Considerable difference. As expected, car feels more dynamic.

Yesterday I had some downtime and I was waiting for the new purge valve anyway, so I cleaned the existing purge valve to see if it would make a difference. I didn't see a big difference.

I still have an issue with STFT, which now has been mostly negative. At load, the STFT becomes closer to normal. You can see the STFT trend up/down at idle times. During idle, the STFT is definitely negative (running rich). I am hoping this is due to the purge valve (new one should be here sometime today) getting stuck open and/or not closing appropriately. Or maybe the car just needs to learn things and will adjust to the correct numbers over some time. After the MAF replacement, I still see the biggest improvement.

https://i.imgur.com/ack4EBp.png

https://i.imgur.com/JqJ3MO2.png

Update again:
Got the new purge valve installed. First look ... Numbers look promising. I'm going to drive it for a bit and rescan, but I do not see the typical rise/drop from the STFT at idle that I have been seeing before. Numbers a little off, but maybe car needs to harmonize.

Quick scan....

https://i.imgur.com/fy4OikS.png

Did you order an OE BMW purge valve or you gonna "add more to the soup?"

Reset fuel adaptations or it will take a few drive cycles


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It's OE

Cool. Will do that now. Going on a long drive.

Thanks!

Hopefully this caps off another steaming pile of andrewwynn BS ;)