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      04-12-2020, 09:10 AM   #1
Refractory
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325i N52B25 Maf issues

There is absolutely no difference in measured air flow in INPA when i connect and disconnect the MAF sensor, even went as far as testing the MAF being connected, but the whole sensor being taken OUT of the intake tube, which in my opinion should make the car go crazy - absolutely NO difference. The car has all of the usual broken MAF symptoms.
When I connect the MAF, I can see the Intake Air Temperature reading react (goes from -49C to an obviously adequate reading), but the Measured Air does not react whatsoever. One of my theories was the connector not making a good connection, but i tightened the pinholes with a needle and still no difference. The reason I'm making this thread is I cannot find a used known good MAF to test with, or a car like mine, so my only way of actually testing is buying a new MAF, but since this one's manufacture date is 2017, I'm suspecting someone maybe changed it because of the same problems, but the problem didn't get resolved. Does anyone have an idea if maybe the ECU could be at fault? Or what other kind of tests and procedures I can do to narrow it down to the Airflow measuring part of the sensor being dead?
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      04-12-2020, 11:45 AM   #2
gbalthrop
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Quote:
Originally Posted by Refractory View Post
There is absolutely no difference in measured air flow in INPA when i connect and disconnect the MAF sensor... Does anyone have an idea if maybe the ECU could be at fault? Or what other kind of tests and procedures I can do to narrow it down to the Airflow measuring part of the sensor being dead?
It's a "German" thing.

If you are looking at the F5 Status Screen, F3 MesswertBlock 3, "Luftmasse gemessen", I believe you will find THAT value is NOT "measured" by the MAF Sensor, but rather "calculated" or "Mapped" based upon engine RPM or ESS reading. On my 328xi N52KP, that value changes in value from 8 at idle to 16, then 24, 32 (at 2,000 RPM), etc. (multiples of 8) as RPM increases. So THAT value is NOT based upon signal from the MAF, but is mapped or computed.

There ARE other screens which show ACTUAL readout of MAF Signal as received by the DME:

1) F1 MesswertBlock 1, "Luftmasse" in Kg/h;
2) F5 Rohwerte ADC & Messwert, which for 2007 & later models with Digital HFM Sensor, shows Sensor signal Raw Value, and corresponding Mass Air Flow in Kg/h;
3) F6 MesswertBlock 6, "Luftmasse" in Kg/h;

My N52KP has a Luftmasse value of ~ 13 Kg/h at idle, as displayed on ANY of those three screens, but a value of "8 Kg/h" on F3 "Luftmasse gemessen" (at idle).

So NOTHING is wrong with your DME or MAF if it behaves as described, just a "misinterpretation" of what INPA is showing on the various screens. If you will let us know what your engine performance issues are in more detail, and any Fault Codes read when connected to your DME (MSV70 or MSV80), using DME > F4 > F3 Fehlerspeicher mit Freeze Frame, along with screenprints of any codes, Freeze Frame Data & Fault Details, we can suggest next steps using INPA.

Best way to share what you are seeing on an INPA screen is to do a ScreenPrint: Shft+PrtSc and then paste that to Paint or photo editor of choice. Then save that as JPG or PNG file format and attach it here so we see exactly what your screen showed.

George
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      04-12-2020, 12:25 PM   #3
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Quote:
Originally Posted by gbalthrop View Post
It's a "German" thing.

If you are looking at the F5 Status Screen, F3 MesswertBlock 3, "Luftmasse gemessen", I believe you will find THAT value is NOT "measured" by the MAF Sensor, but rather "calculated" or "Mapped" based upon engine RPM or ESS reading. On my 328xi N52KP, that value changes in value from 8 at idle to 16, then 24, 32 (at 2,000 RPM), etc. (multiples of 8) as RPM increases. So THAT value is NOT based upon signal from the MAF, but is mapped or computed.

There ARE other screens which show ACTUAL readout of MAF Signal as received by the DME:

1) F1 MesswertBlock 1, "Luftmasse" in Kg/h;
2) F5 Rohwerte ADC & Messwert, which for 2007 & later models with Digital HFM Sensor, shows Sensor signal Raw Value, and corresponding Mass Air Flow in Kg/h;
3) F6 MesswertBlock 6, "Luftmasse" in Kg/h;

My N52KP has a Luftmasse value of ~ 13 Kg/h at idle, as displayed on ANY of those three screens, but a value of "8 Kg/h" on F3 "Luftmasse gemessen" (at idle).

So NOTHING is wrong with your DME or MAF if it behaves as described, just a "misinterpretation" of what INPA is showing on the various screens. If you will let us know what your engine performance issues are in more detail, and any Fault Codes read when connected to your DME (MSV70 or MSV80), using DME > F4 > F3 Fehlerspeicher mit Freeze Frame, along with screenprints of any codes, Freeze Frame Data & Fault Details, we can suggest next steps using INPA.

Best way to share what you are seeing on an INPA screen is to do a ScreenPrint: Shft+PrtSc and then paste that to Paint or photo editor of choice. Then save that as JPG or PNG file format and attach it here so we see exactly what your screen showed.

George
I've been having serious performance issues with the car for like 5 months now. It stalls, cuts out, hesitates, has choppy acceleration, sometimes smokes a lot from the exhaust, sometimes refuses to go over certain RPM (usually about 2000 while applying throttle the car literally nosedives), fuel consumption is through the roof, when stationary, while revving, there is a noticeable cutoff at about 1500 rpm and you can hear a loud "pop" coming from the engine. ALL of these problems occur UNDER 3000 RPM, once the engine gets above 3000 RPM everything is absolutely perfect and smooth as butter. The most interesting part of all is - when I reset all adaptations in ISTA or INPA and do the corresponding re-adaptation procedures, the car behaves much better - then, with time, it just goes back to the same terrible state. I've pretty much tried everything (solenoids, disas, PCV replacement, spark plugs, tested fuel pressure on the rail) except a new MAF and new O2 sensors. There are absolutely no trouble codes, except an occasional, rare BAD MIXTURE code on both banks.

-In INPA, something that stands out the most, is the "Injection Correction Time" parameter, which can constantly be seen at around 25-30%.

-The car has pretty regular long cranks after sitting for at least 5-6 hours

-The fact that there is absolutely no difference in engine performance with the maf connected / disconnected / connected BUT TAKEN OUT OF THE INTAKE TUBE, is leading me in the direction, that the MAF sensor just is not doing what it's supposed to be doing.

-The car is pre-2007 so the HFM screen just shows zeros.

By the way - I have ISTA installed as well, if you're experienced with it we can use it instead of the poorly-translated INPA.


In this video you can hear the engine stumble after i let go of the gas after revving, like it's trying not to stall, you can also see other parameters like the Duration of Injection change drastically.


And in THIS video, you can see Spannung Luftmasse, which means Air Mass Voltage, being a constant 0.
I hope I provided enough information to clear things up a bit.
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      04-12-2020, 12:52 PM   #4
Refractory
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I just made a brand new video, showcasing all 3 of the MWBs. If you have sound on your platform you can also hear the engine hesitate at around 1500 when i give it throttle.





The air seems too low to me. Judging from this youtube video where the guy was testing the same engine's MAF, his reading was going all the way up to 380 KG/H at about 4000ish RPM (judging from engine sound alone). Link for the video below. SKIP TO ABOUT 5:08 TO SEE THE READINGS



Last edited by Refractory; 04-12-2020 at 12:59 PM..
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      04-12-2020, 04:10 PM   #5
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At the very least, if anyone could check their Messwertblock ADC in INPA and confirm whether Spannung Luftmasse (Airmass Voltage) shows a reading different to zero, or if it's just one of those lost in translation / interpretation things where it's 0 for everyone, I'd massively appreciate it!
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