M5 Comp stalling when setting off HELP!

KillerM3 · 08-09-2022, 01:04 PM

Afternoon all, new here to the group. Had my M5 since last April 2021

It has always had a problem where it stalls when setting off and accompanied by an error on bank 1 and 2 that says air to fuel mixture too lean.

So far it has had brand new injectors, a fuel pump, new O2 sensors new MAF new spark plugs 1 new coil pack replacement ECUs with a fresh flash to factory incase it was ever previously mapped. I even removed the cats as one of the mechanics suggested they may be degraded.

Car has full service history

I am currently at a total loss as to what to do with it.

Anyone ever experienced anything like this? Or possible solutions. I'm fairly certain everything that could cause the fuel mixture error has been replaced.

Currently feel like driving it into a wall. It drives absolutely faultlessly apart from the stalling when you are setting off.

It doesn't do it when cold when the revs are higher only when warm and only when setting off. Apart from that no misfires, errors or anything else.

The oil smells strongly of petrol which I put down to the injectors but they were all replaced.

Any pointers would be much appreciated.

M5Rick · 08-09-2022, 05:24 PM

What's the mileage on your Competition and has it had any engine mods.

KillerM3 · 08-09-2022, 07:22 PM

It's on 65000 miles. When I bought it it was standard but when we changed the ECUs we noticed the old ones had been tampered with. Everything appears to be standard though so not sure. There is a receipt for warranty work to the cylinder heads a couple of years ago and it had a BMW warranty til 2020 a year before I bought it.

M5Rick · 08-10-2022, 05:02 AM

It's had new EU6 injectors and you are still smelling fuel in the oil, who changed the injectors.. I always ask for the old parts (like spark plugs) back and I wouldn't use the car anymore if fuel is going into oil. I suggest an oil change as soon as, oil is getting diluted with petrol mix.

KillerM3 · 08-11-2022, 02:53 PM

Yes I have the old injectors and it's had 2 oil changes in the last 1500 miles. Apparently one of the old injectors failed but I changed the whole set. I can't figure out where else fuel could be mixing with oil. If a cylinder was leaking I'm sure it would be running rough in general.

M5Rick · 08-12-2022, 03:02 AM

There's only one way fuel can be getting into oil and that's through an injector, I can only think you may have a faulty new injector. Did BMW change them? They have two year warranty on all their new parts they fit.

fstm5 · 08-15-2022, 04:16 PM

Quote:

Originally Posted by KillerM3

Afternoon all, new here to the group. Had my M5 since last April 2021

It has always had a problem where it stalls when setting off and accompanied by an error on bank 1 and 2 that says air to fuel mixture too lean.

So far it has had brand new injectors, a fuel pump, new O2 sensors new MAF new spark plugs 1 new coil pack replacement ECUs with a fresh flash to factory incase it was ever previously mapped. I even removed the cats as one of the mechanics suggested they may be degraded.

Car has full service history

I am currently at a total loss as to what to do with it.

Anyone ever experienced anything like this? Or possible solutions. I'm fairly certain everything that could cause the fuel mixture error has been replaced.

Currently feel like driving it into a wall. It drives absolutely faultlessly apart from the stalling when you are setting off.

It doesn't do it when cold when the revs are higher only when warm and only when setting off. Apart from that no misfires, errors or anything else.

The oil smells strongly of petrol which I put down to the injectors but they were all replaced.

Any pointers would be much appreciated.

Try switching around the maf's with left and right, fixed all my stalling issues

Could be a DCT issue as well

KillerM3 · 08-17-2022, 01:54 PM

No but they were original BMW equipment. I wonder if it's vanos related or whatever iteration of it the F10 has.

I did switch the Mafs and replace one. Wouldn't know where to start with the dct. Doesn't have any errors and appears to go through al the gears perfectly.

KillerM3 · 08-17-2022, 02:01 PM

Quote:

Originally Posted by fstm5

Try switching around the maf's with left and right, fixed all my stalling issues

Could be a DCT issue as well

I did think of this but seems unlikely given the air mixture error

08-09-2022, 01:04 PM	#1
KillerM3 New Member 0 Rep 7 Posts Drives: F80 M3 Join Date: Dec 2018 Location: UK iTrader: (0)	M5 Comp stalling when setting off HELP! Afternoon all, new here to the group. Had my M5 since last April 2021 It has always had a problem where it stalls when setting off and accompanied by an error on bank 1 and 2 that says air to fuel mixture too lean. So far it has had brand new injectors, a fuel pump, new O2 sensors new MAF new spark plugs 1 new coil pack replacement ECUs with a fresh flash to factory incase it was ever previously mapped. I even removed the cats as one of the mechanics suggested they may be degraded. Car has full service history I am currently at a total loss as to what to do with it. Anyone ever experienced anything like this? Or possible solutions. I'm fairly certain everything that could cause the fuel mixture error has been replaced. Currently feel like driving it into a wall. It drives absolutely faultlessly apart from the stalling when you are setting off. It doesn't do it when cold when the revs are higher only when warm and only when setting off. Apart from that no misfires, errors or anything else. The oil smells strongly of petrol which I put down to the injectors but they were all replaced. Any pointers would be much appreciated. Last edited by KillerM3; 08-09-2022 at 01:27 PM..
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08-09-2022, 05:24 PM	#2
M5Rick General 59630 Rep 19,450 Posts Drives: M5 F10 DCT Gunmetal Join Date: Aug 2018 Location: Southern England iTrader: (0)	What's the mileage on your Competition and has it had any engine mods.
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08-09-2022, 07:22 PM	#3
KillerM3 New Member 0 Rep 7 Posts Drives: F80 M3 Join Date: Dec 2018 Location: UK iTrader: (0)	It's on 65000 miles. When I bought it it was standard but when we changed the ECUs we noticed the old ones had been tampered with. Everything appears to be standard though so not sure. There is a receipt for warranty work to the cylinder heads a couple of years ago and it had a BMW warranty til 2020 a year before I bought it.
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08-10-2022, 05:02 AM	#4
M5Rick General 59630 Rep 19,450 Posts Drives: M5 F10 DCT Gunmetal Join Date: Aug 2018 Location: Southern England iTrader: (0)	It's had new EU6 injectors and you are still smelling fuel in the oil, who changed the injectors.. I always ask for the old parts (like spark plugs) back and I wouldn't use the car anymore if fuel is going into oil. I suggest an oil change as soon as, oil is getting diluted with petrol mix.
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08-11-2022, 02:53 PM	#5
KillerM3 New Member 0 Rep 7 Posts Drives: F80 M3 Join Date: Dec 2018 Location: UK iTrader: (0)	Yes I have the old injectors and it's had 2 oil changes in the last 1500 miles. Apparently one of the old injectors failed but I changed the whole set. I can't figure out where else fuel could be mixing with oil. If a cylinder was leaking I'm sure it would be running rough in general. Last edited by KillerM3; 08-11-2022 at 03:12 PM..
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08-12-2022, 03:02 AM	#6
M5Rick General 59630 Rep 19,450 Posts Drives: M5 F10 DCT Gunmetal Join Date: Aug 2018 Location: Southern England iTrader: (0)	There's only one way fuel can be getting into oil and that's through an injector, I can only think you may have a faulty new injector. Did BMW change them? They have two year warranty on all their new parts they fit.
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08-17-2022, 01:54 PM	#8
KillerM3 New Member 0 Rep 7 Posts Drives: F80 M3 Join Date: Dec 2018 Location: UK iTrader: (0)	No but they were original BMW equipment. I wonder if it's vanos related or whatever iteration of it the F10 has. I did switch the Mafs and replace one. Wouldn't know where to start with the dct. Doesn't have any errors and appears to go through al the gears perfectly.
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