01-23-2020, 03:48 PM | #1 |
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Erratic MAF sensor reading
Hi everyone,
Looking through some live data with my scan tool on my f30 2012 320D and came across flow rate for mass air flow sensor, the car was idling and the MAF sensor reading was going crazy. It goes up and down constantly, anywhere from 1 g/s to 18 g/s, it also jumps from a low number to a high number, there's no flow. This is all at idle, when driving the same jumping happens. So I've cleaned the Maf, changed the maf, changed the air filters and still the same thing keeps happening. Ever since I've owned the car its also felt sluggish compared to my 2010 318D. Does anyone know if this MAF reading is normal? Thanks! Sam Last edited by Srobbo122; 01-23-2020 at 04:01 PM.. |
01-24-2020, 07:31 AM | #4 |
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I would also try a different tool, or log with Testo (uses factory protocols) onto laptop in realtime
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01-24-2020, 06:04 PM | #5 |
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Thanks for the replies everyone!
Thanks, eugene89us, looking forward to seeing what your readings are! I tried cleaning the MAP today, although it was very dirty it still did not solve the issue I hooked my other scan tool up today and I am getting the same erratic readings. |
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01-25-2020, 06:58 AM | #6 |
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bit of a shot in the dark, but could it poss be to do with a dodgy thermostat and/or coolant temp sensor, and the ecu is flicking bewtween closed/open loop because of wrong feedback from the sensor,
would have thought it throw engine light mind, but stranger things have happened! |
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01-25-2020, 01:46 PM | #7 |
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So my car has times when it goes into unstable idle. Still under warranty, but no codes and dealer (including BMW engineer) could not figure fault out. Below are graphs, both at idle. One with unstable idle (see my other posts on unstable idle, I have it on video) and one with stable idle. I think MAF and idle instability is a symptom, not the cause.
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02-04-2020, 06:09 AM | #8 | |
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Quote:
I tried cleaning MAF for the first time and it went away and could feel the performance difference too. Then cleaned the dirty MAP sensor too but after some time the code came back and itself cancels after a few runs. However, the car is awful to drive, gear shifts are horrible too. cleaned the MAF again but no difference to the performance. According to the scan tool MAF reading are flactuating at idle 1.5g/s to 16g/s let me know if you have rectify the issue. cheers |
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09-21-2021, 03:41 AM | #9 |
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Hi everyone!
Did any of you ever find the root cause and/or a solution? I see the exact same behaviour when I am reading my MAF values through an OBD reader. It is a different car model, F11 520D, but the same engine N47. |
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09-21-2021, 08:52 AM | #10 |
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Have any of you tried cleaning your EGR valves? I think a sticking EGR valve could also cause MAF numbers to be off.
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09-21-2021, 09:23 AM | #11 | |
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Performance gains from an intake upgrade are minimal (<5%) and can be had with a simple drop-in free flow airfilter such as aFe or K&N with no potential downside. If an aftermarket intake is desired for a sound increase, be aware that there is the potential for a poorly designed aftermarket intake to effect the MAF and possibly degrade performance. IMO: MST seems to have an excellent combination of performance and sound increase. |
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09-22-2021, 12:30 PM | #12 |
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Thanks for the responses.
Yes, I recently cleaned my EGR. Not that I had any problems with it, more as a precaution. No modifications on the intake on my car, all stock and a quite new quality air filter. |
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03-28-2024, 10:00 PM | #13 |
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I can vouch for that. Yesterday, I tried measuring the MAF after my 320d came from the EGR recall and using the OBDLink app, and I got these erratic values. Using the same PID but in BimmerLink, I got good and stable readings. Please double-check with another app.
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04-05-2024, 04:58 AM | #14 |
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I'm having same issue, erratic readings, Done all sorts of things but still no change. One thing i wonder is if it has a co-relation with the oxygen sensor as i am running stage 2 with o2 OFF, but even after disconnecting the o2 sensor it still show 0.8V-0.9V constant. Im wondering if i have some faulty ECU electric monitor or something.
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