Engine cut-out when clutch disengaged (at speed!)

DC82 · 07-13-2020, 12:57 AM

Good morning!

I have an odd issue on my E90 n43 318i MT that I'm hoping someone may be able to help diagnose..

I have just had the timing chain assembly replaced.

Unfortunately on my drive home from the garage the car started showing some new behaviours.

Firstly, the car sounds much louder and "sportier," if you like, than before. Much more growl to the engine when accelerating. Not a huge issue but it used to be very quiet and refined and now it sounds like a car with a much, much bigger engine. Odd, but perhaps not a massive issue. I only mention it as it might give a clue to the bigger issue.

The bigger issue is that, once the car is up to anything over around 30mph, depressing the clutch causes the revs to drop to idle (~800 as usual) then carry on all the way down to zero where the engine silently cuts out. You the realise you're just cruising along with the engine off.

The auto start-stop will kick in when the clutch pedal is released and jerk the car back into life (in gear usually, so it's a bit abrupt). If slowing to a junction and coming to a stop with the clutch down (which I sometimes do as I'm not a perfect driver!) I end up sat there with the engine off, and may have to start it again manually.

Disabling auto start-stop just causes the engine to remain off, i.e. doesn't restart the engine when the clutch comes back up. It still drops the revs and kills the engine as above.

As far as I'm aware, this is not normal behaviour for this or any car. Basically, I find myself rolling down the road with the engine off. Worrying.

I've sent it back to the garage but I'm not optimistic they'll diagnose it correctly, and think they might try and screw me over on this. They ran a diagnostic and it came up with a fuel pump code - could this be it? Feels unlikely, but maybe?

Do you guys have any ideas what this might be, or have come across it in the past? I'm thinking MAF sensor, but it's only happening since that timing chain replacement.

Thanks for any help or insight!

E92William · 07-13-2020, 02:19 AM

Take it back to that garage they have to own up to it. Car wasn't doing it at all before they replaced the chain. Also weird that the engine is somehow louder now, wonder if there's an exhaust leak or some bs like an air box or scoop not seated correctly. My e92 made significantly more intake noise when the air scoop for the air box wasn't on.
First thing I'd look into is obviously the fuel pump code because that's the first and only clue. You can disconnect the maf temporarily and see how it runs and if it does it, maf sensors sometimes go out without giving any codes.

DC82 · 07-13-2020, 08:07 AM

So just like that, this is resolved!

Turns out there was a split in the air intake pipe, presumably as a result of the work done. New one fitted, runs perfectly now.

E92William · 07-13-2020, 02:10 PM

There you go. Was that what was causing the car to run louder too?

DC82 · 07-15-2020, 03:49 PM

I took it for a decent drive today, about 60 miles or so, and I'm positive that it actually still does have a much lower rumble to the engine now, but not as pronounced as before the intake ws changed.

I'll live with it, as apart from that it's running great.

07-13-2020, 12:57 AM	#1
DC82 New Member 2 Rep 5 Posts Drives: BMW E90 318i m sport Join Date: Jul 2020 Location: UK iTrader: (0)	Engine cut-out when clutch disengaged (at speed!) Good morning! I have an odd issue on my E90 n43 318i MT that I'm hoping someone may be able to help diagnose.. I have just had the timing chain assembly replaced. Unfortunately on my drive home from the garage the car started showing some new behaviours. Firstly, the car sounds much louder and "sportier," if you like, than before. Much more growl to the engine when accelerating. Not a huge issue but it used to be very quiet and refined and now it sounds like a car with a much, much bigger engine. Odd, but perhaps not a massive issue. I only mention it as it might give a clue to the bigger issue. The bigger issue is that, once the car is up to anything over around 30mph, depressing the clutch causes the revs to drop to idle (~800 as usual) then carry on all the way down to zero where the engine silently cuts out. You the realise you're just cruising along with the engine off. The auto start-stop will kick in when the clutch pedal is released and jerk the car back into life (in gear usually, so it's a bit abrupt). If slowing to a junction and coming to a stop with the clutch down (which I sometimes do as I'm not a perfect driver!) I end up sat there with the engine off, and may have to start it again manually. Disabling auto start-stop just causes the engine to remain off, i.e. doesn't restart the engine when the clutch comes back up. It still drops the revs and kills the engine as above. As far as I'm aware, this is not normal behaviour for this or any car. Basically, I find myself rolling down the road with the engine off. Worrying. I've sent it back to the garage but I'm not optimistic they'll diagnose it correctly, and think they might try and screw me over on this. They ran a diagnostic and it came up with a fuel pump code - could this be it? Feels unlikely, but maybe? Do you guys have any ideas what this might be, or have come across it in the past? I'm thinking MAF sensor, but it's only happening since that timing chain replacement. Thanks for any help or insight!
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07-13-2020, 02:19 AM	#2
E92William Banned 1999 Rep 2,025 Posts Drives: 2008 E92 328xi Join Date: Nov 2019 Location: Miami iTrader: (0) Garage List 2008 BMW 328xi [0.00]	Take it back to that garage they have to own up to it. Car wasn't doing it at all before they replaced the chain. Also weird that the engine is somehow louder now, wonder if there's an exhaust leak or some bs like an air box or scoop not seated correctly. My e92 made significantly more intake noise when the air scoop for the air box wasn't on. First thing I'd look into is obviously the fuel pump code because that's the first and only clue. You can disconnect the maf temporarily and see how it runs and if it does it, maf sensors sometimes go out without giving any codes.
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07-13-2020, 08:07 AM	#3
DC82 New Member 2 Rep 5 Posts Drives: BMW E90 318i m sport Join Date: Jul 2020 Location: UK iTrader: (0)	So just like that, this is resolved! Turns out there was a split in the air intake pipe, presumably as a result of the work done. New one fitted, runs perfectly now.
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07-13-2020, 02:10 PM	#4
E92William Banned 1999 Rep 2,025 Posts Drives: 2008 E92 328xi Join Date: Nov 2019 Location: Miami iTrader: (0) Garage List 2008 BMW 328xi [0.00]	There you go. Was that what was causing the car to run louder too?
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07-15-2020, 03:49 PM	#5
DC82 New Member 2 Rep 5 Posts Drives: BMW E90 318i m sport Join Date: Jul 2020 Location: UK iTrader: (0)	I took it for a decent drive today, about 60 miles or so, and I'm positive that it actually still does have a much lower rumble to the engine now, but not as pronounced as before the intake ws changed. I'll live with it, as apart from that it's running great.
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