F20 118i Engine idles at high RPMs - P0171 Error Code
Discussion
Hello everyone.
I have a BMW F20 118i 1.5 2015 (65 plate) with 30k miles on it. The problem I have is that the engine doesn't idle normally and I am not sure what is happening, and how to actually name the issue. Is it engine hunting? Anyway whenever the engine warm and in idle it revs itself to around 1400-1800 rpms. I have also had check engine light on twice with an error code "P0171 Systeam Too Lean Bank 1".
I have recorded a short video of what it looks like. YouTube link below:
https://www.youtube.com/watch?v=vQ31M3QEoTI
I have replaced Mass Airflow Sensor but this didn't work(lucky store took it back). Did a service on the car just recently too including oil change, filters change, and spark plugs change. No results. Can't visually see any leaks and I have tried spraying breaks cleaner onto hoses to check if it would affect engine idling.
I can bring it no BMW for 'inspection' that will cost me £115, I wonder if thats the best thing to do.
Here is another video of the car rolling and the mpg meter indicating low economy once the car is in neutral. (Turn subtitles ON)
https://www.youtube.com/watch?v=vR-R2hJr660
Any ideas? Thank you.
I have a BMW F20 118i 1.5 2015 (65 plate) with 30k miles on it. The problem I have is that the engine doesn't idle normally and I am not sure what is happening, and how to actually name the issue. Is it engine hunting? Anyway whenever the engine warm and in idle it revs itself to around 1400-1800 rpms. I have also had check engine light on twice with an error code "P0171 Systeam Too Lean Bank 1".
I have recorded a short video of what it looks like. YouTube link below:
https://www.youtube.com/watch?v=vQ31M3QEoTI
I have replaced Mass Airflow Sensor but this didn't work(lucky store took it back). Did a service on the car just recently too including oil change, filters change, and spark plugs change. No results. Can't visually see any leaks and I have tried spraying breaks cleaner onto hoses to check if it would affect engine idling.
I can bring it no BMW for 'inspection' that will cost me £115, I wonder if thats the best thing to do.
Here is another video of the car rolling and the mpg meter indicating low economy once the car is in neutral. (Turn subtitles ON)
https://www.youtube.com/watch?v=vR-R2hJr660
Any ideas? Thank you.
dmarkovina said:
A three cylinder engine has only one bank of cylinders so that's fine (I would expect bank 2 to have no readings not 1 though).
What are the fuel trims readings when idling - both short and long?
And is there any difference in when you unplug the MAF?
Sorry that's right I meant Bank 1 Sensor 1 doesn't give readings. I believe there are two sensors, post catalyst and in front of the catalyst so the Sensor 1 must be the front one I assume.What are the fuel trims readings when idling - both short and long?
And is there any difference in when you unplug the MAF?
This is how it looks.
When I unplug the MAF sensor the rpms drop and do not come back, but I did replace the MAF sensor with a new one (BOSCH) and it is just the same.
You can't get fuel trims with your device - once you cleared the lean error code it would come back or not? The easiest and cheapest way of running own diagnostics is via a Bluetooth/wireless OBD dongle and apps via Google Play/App store. Or ideally dedicated BMW sw - but that costs money. I use MotorData OBD app on my android phone. Some people also use Carly app - but it's subscription based I think. BMW Rheingold sw used by dealers not only log errors but has a proper diagnostics module where it navigates user on how to perform tests if necessary.
If idle is ok with MAF unplugged I would think that you do not have an air leak - as if you did the pre-programmed map would not recognise the extra air, so it should run lean and idle should drop as opposed to being too high.
So it may well be that o2 sensor is off - but I would not expect them to fail so prematurely. If your new MAF is not original BMW or from reputable make it may well be that it's off. Also it' worth checking if you're on the latest sw version - they do iron out bugs with time.
https://www.bmw-sg.com/forums/threads/118i-engine-...
P.S.
You air filter is clean?
If idle is ok with MAF unplugged I would think that you do not have an air leak - as if you did the pre-programmed map would not recognise the extra air, so it should run lean and idle should drop as opposed to being too high.
So it may well be that o2 sensor is off - but I would not expect them to fail so prematurely. If your new MAF is not original BMW or from reputable make it may well be that it's off. Also it' worth checking if you're on the latest sw version - they do iron out bugs with time.
https://www.bmw-sg.com/forums/threads/118i-engine-...
P.S.
You air filter is clean?
Hi. The code came back only once after clearing the code and never again since. I will have a look at the carly app but I have managed to get fuel trim readings, and here they are.
The first, second and the last picture is the engine idling itself. The pictures with 2.9k~ rpm is me pressing the gas pedal.
Air filter has been recently changed to a brand new one along with oil, oil filter and spark plugs. The MAF sensor was from BOSCH.
I'll have a look at the software, thanks!
The first, second and the last picture is the engine idling itself. The pictures with 2.9k~ rpm is me pressing the gas pedal.
Air filter has been recently changed to a brand new one along with oil, oil filter and spark plugs. The MAF sensor was from BOSCH.
I'll have a look at the software, thanks!
dmarkovina said:
y
If idle is ok with MAF unplugged I would think that you do not have an air leak - as if you did the pre-programmed map would not recognise the extra air, so it should run lean and idle should drop as opposed to being too high.
Completely backwards - if you have an air leak or u are getting extra air mass in the intake sustem somehow then the maf will be registering a lower reading as less air will be getting sucked through the air mass meter as the air is getting in other ways. With it disconnected it will run on a predetermined value which will mean it runs fine as it won’t care where the air is being supplied fromIf idle is ok with MAF unplugged I would think that you do not have an air leak - as if you did the pre-programmed map would not recognise the extra air, so it should run lean and idle should drop as opposed to being too high.
Btw it could be getting the extra air from an air leak, or a vacuum leak, egr sticking open or being held open, etc
Edited by Elliot2000 on Wednesday 30th January 18:47
My experience with M54 engine, with MAF unplugged, was, if I remember correctly, hesitation due to I thought, more air being sucked in the cylinder than ECU would expect, leading to lean mixture.
As I have LPG fitted and being able to play in real time with fuelling maps, I noticed that a lean situation leads to idle revs dropping as in "off the cliff" and then ECU (with MAF connected) trying to play catch up and compensate via fuel trim. I understood that with MAF disconnected ECU was ignoring 02 sensor readings and just sticking with the default map?
Another tel tel sign of an air leak I noticed was the pressure drop (vs ambient pressure of 1 bar) being lower than there would have been without the air leak. I can see from TAM24's photos, that with his valvetronic engine he gest a constant 0.9bar of MAP - so nearly ambient pressure both at idle and with open throttle - expected as there is little vacuum in the manifold due to having no throttle body..
What puzzles me is why it idles so high - I would expect this to be a consequence of too much fuel entering the engine. But o2 sensor says it is lean both short and long term. Could it indeed be a dodgy o2 sensor?
Happily stand corrected.
As I have LPG fitted and being able to play in real time with fuelling maps, I noticed that a lean situation leads to idle revs dropping as in "off the cliff" and then ECU (with MAF connected) trying to play catch up and compensate via fuel trim. I understood that with MAF disconnected ECU was ignoring 02 sensor readings and just sticking with the default map?
Another tel tel sign of an air leak I noticed was the pressure drop (vs ambient pressure of 1 bar) being lower than there would have been without the air leak. I can see from TAM24's photos, that with his valvetronic engine he gest a constant 0.9bar of MAP - so nearly ambient pressure both at idle and with open throttle - expected as there is little vacuum in the manifold due to having no throttle body..
What puzzles me is why it idles so high - I would expect this to be a consequence of too much fuel entering the engine. But o2 sensor says it is lean both short and long term. Could it indeed be a dodgy o2 sensor?
Happily stand corrected.
Edited by dmarkovina on Thursday 31st January 18:48
https://www.minif56.com/forum/showthread.php?78434...
Mini Cooper F56 has the same engine as yours. Maybe the same tank vent issue? The last post.
You need to have the error log checked to start with - think with the latest BMWs you would need Rheingold software.
Mini Cooper F56 has the same engine as yours. Maybe the same tank vent issue? The last post.
You need to have the error log checked to start with - think with the latest BMWs you would need Rheingold software.
Edited by naturalaspiration on Wednesday 6th February 07:27
Hi mate. Unfortunately no, I had a friend with a proper diagnostics computer have a look at it too but we couldn't come to what it was. I tried doing a smoke test but this didn't work as the car was in closed loop and the smoke didn't get anywhere.
What is strange to me is that the problem happens only once the engine fully warms up, so like after 15 minutes of driving. Loss of power, high idling... You know what actually when the engine idles high and if I press the AC ON and OFF, turn off the lights ON and OFF the idling instantly changes... This doesn't fix anything just affects engine work for a short while and then it goes bad again.
Started getting this problem after trying to launch the car, now I really regret it but would that one time be really the cause of all this? Damn. I guess I have no choice but to take it to BMW. Makes me wonder if they'll be able to find the problem in the first hour, for £115 per hour.
What is strange to me is that the problem happens only once the engine fully warms up, so like after 15 minutes of driving. Loss of power, high idling... You know what actually when the engine idles high and if I press the AC ON and OFF, turn off the lights ON and OFF the idling instantly changes... This doesn't fix anything just affects engine work for a short while and then it goes bad again.
Started getting this problem after trying to launch the car, now I really regret it but would that one time be really the cause of all this? Damn. I guess I have no choice but to take it to BMW. Makes me wonder if they'll be able to find the problem in the first hour, for £115 per hour.
Edited by TAM24 on Sunday 17th February 17:24
naturalaspiration said:
https://www.minif56.com/forum/showthread.php?78434...
Mini Cooper F56 has the same engine as yours. Maybe the same tank vent issue? The last post.
You need to have the error log checked to start with - think with the latest BMWs you would need Rheingold software.
BMW diagnosed and found the problem, exactly the same issue as above. This little guy:Mini Cooper F56 has the same engine as yours. Maybe the same tank vent issue? The last post.
You need to have the error log checked to start with - think with the latest BMWs you would need Rheingold software.
Edited by naturalaspiration on Wednesday 6th February 07:27
Even if I wanted to check this I don't think I could do it on my own... BMW charged £115 for diagnosis, now they are asking £142 for the part and the labour. I couldn't leave the car with them overnight, will have to do it later this week. I hope that will be the end of my problems for some time, been only getting issues with the car ever since I got it, not impressed.
I guess the faulty valve is creating some sort of vacuum in the tank, messing up the pressure in the manifold through which the fuel fumes are being vented (usually via a charcoal canister - at least in the older E models). On my E38 (metal tank) this led to the tank warping and breaking. Cheap workaround entailed just drilling a small hole in the fuel filler cap and stuffing in a piece of kitchen sponge to prevent the petrol fumes from coming out. I did this 10 years ago on my and have had no issues ever since - never bothered replacing the clogged charcoal canister.
I am by no means saying that your issue is the same as described above, but you could give it a go and see if it makes any difference - by not fully tightening the filler cap (leaving it a little lose but again not completely undone). If you're wary about the procedure just lock the car from the inside to be on a safe side - this will also lock the fuel filler flap.
Finger's crossed.
I am by no means saying that your issue is the same as described above, but you could give it a go and see if it makes any difference - by not fully tightening the filler cap (leaving it a little lose but again not completely undone). If you're wary about the procedure just lock the car from the inside to be on a safe side - this will also lock the fuel filler flap.
Finger's crossed.
Edited by naturalaspiration on Tuesday 26th February 22:35
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