N52 Rough idle and turn 0ff help

MaximoSantiago · 10-24-2023, 06:40 PM

i have a 2006 BMW e90 330i with the n52

A while ago the car started idling rough and would occasionally shut off at a stop. after researching the codes I decided it was the MAF so I installed a new one from FCP Euro (the OE VDO MAF) and the car ran fine for awhile until one day at work, it started and then died instantly and kept doing that. I unplugged the MAF and it started and got home with no issues. the rough idle would just bounce between 1200 and 600 rpms but would drive fine once I was on the gas. I took it to my shop and got code 2DOF -MAF sensor signal. I cleared it and drove the car fine with the slight rough idle. next day after work, I took it back to my shop scanned again and got code 2DOF again and 2F08 -intake air temp sensor signal. I cleared them and the car was fine besides the idle. Until today, after work while dropping off my coworkers the car started to bog out even while I was on the gas so i knew it was gonna stall as soon as I stopped, I pulled over and sure enough it died. I unplugged the MAF again and it started right up and got me home fine. ill scan again later tonight and see what codes come up
there aren't any cracks in the intake boot and so far from everything I've read and watched I'm thinking its a air leak from an old CCV hose or wiring issue with the MAF. What else
could be causing this, what should i check or look for or test?

unicornsareus · 10-28-2023, 01:34 PM

I think you have a vacuum leak - and a bad one.

The way I diagnosed my issue was outright dangerous and I do not recommend it. I started the car, and sprayed some brake cleaner at different vacuum and intake component connections. It'll run rough, but when the brake cleaner fumes get sucked in - it'll get smoother. I initially thought it was my Throttle Body gasket - but it ended up being OK. Please do not burn down your car - and I will not be held responsible for if you burn your car down or anything else with it.

I just finished repairing my E83 for this issue.

Mine ended up being a bad CCV/valve cover throwing throwing stupid amounts of oil into my intake manifold combined with an intake manifold that was splitting by the TB connection and had a vacuum leak there.

I fixed the manifold plastic with some plastic bonder - it isn't a long term fix but at least it runs decently.

The reason the car runs fine without the MAF plugged in is because it goes into a limp/safe mode without it. When your MAF is plugged in, its only accounting for the air the MAF senses and not the air that is going into your intake through the vacuum leak. This ends up being an extremely lean mixture of air/fuel and therefore it just dies especially when coasting to a stop.

MaximoSantiago · 02-23-2024, 06:16 PM

so, i had a bad vacuum leak from the ccv hose but i replaced it and it ran way better for a little but then had codes 2A2E 2A2F 2D06 they went away for a while after some driving then came back, i found these threads that sound like my same exact issue and symptoms

https://www.e90post.com/forums/showt...highlight=2d06
https://www.e90post.com/forums/showt...=905209&page=2
https://www.e90post.com/forums/showthread.php?t=1113350

i replaced the maf connector yesterday and it drove perfect, idle was perfect, felt powerful up until it randomly stalled at a light with no warning, rough idle is back, same codes are back and im losing my mind i cleaned the connectors about to go back to my shop, i unplugged the maf and the car stayed running so maybe this maf already went bad? maybe lose ccv hose? 02 sensors? im about to go to my shop and clean the solenoids and hook up the good scanner, will update when i can

10-24-2023, 06:40 PM	#1
MaximoSantiago Registered 0 Rep 2 Posts Drives: 2006 bmw 330i e90 Join Date: Oct 2023 Location: salt lake city utah iTrader: (0)	N52 Rough idle and turn 0ff help i have a 2006 BMW e90 330i with the n52 A while ago the car started idling rough and would occasionally shut off at a stop. after researching the codes I decided it was the MAF so I installed a new one from FCP Euro (the OE VDO MAF) and the car ran fine for awhile until one day at work, it started and then died instantly and kept doing that. I unplugged the MAF and it started and got home with no issues. the rough idle would just bounce between 1200 and 600 rpms but would drive fine once I was on the gas. I took it to my shop and got code 2DOF -MAF sensor signal. I cleared it and drove the car fine with the slight rough idle. next day after work, I took it back to my shop scanned again and got code 2DOF again and 2F08 -intake air temp sensor signal. I cleared them and the car was fine besides the idle. Until today, after work while dropping off my coworkers the car started to bog out even while I was on the gas so i knew it was gonna stall as soon as I stopped, I pulled over and sure enough it died. I unplugged the MAF again and it started right up and got me home fine. ill scan again later tonight and see what codes come up there aren't any cracks in the intake boot and so far from everything I've read and watched I'm thinking its a air leak from an old CCV hose or wiring issue with the MAF. What else could be causing this, what should i check or look for or test? Last edited by MaximoSantiago; 10-24-2023 at 06:46 PM..
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10-28-2023, 01:34 PM	#2
unicornsareus New Member 17 Rep 10 Posts Drives: 2008 328xi sedan, 2008 X3 Join Date: Oct 2023 Location: Canadia iTrader: (0)	I think you have a vacuum leak - and a bad one. The way I diagnosed my issue was outright dangerous and I do not recommend it. I started the car, and sprayed some brake cleaner at different vacuum and intake component connections. It'll run rough, but when the brake cleaner fumes get sucked in - it'll get smoother. I initially thought it was my Throttle Body gasket - but it ended up being OK. Please do not burn down your car - and I will not be held responsible for if you burn your car down or anything else with it. I just finished repairing my E83 for this issue. Mine ended up being a bad CCV/valve cover throwing throwing stupid amounts of oil into my intake manifold combined with an intake manifold that was splitting by the TB connection and had a vacuum leak there. I fixed the manifold plastic with some plastic bonder - it isn't a long term fix but at least it runs decently. The reason the car runs fine without the MAF plugged in is because it goes into a limp/safe mode without it. When your MAF is plugged in, its only accounting for the air the MAF senses and not the air that is going into your intake through the vacuum leak. This ends up being an extremely lean mixture of air/fuel and therefore it just dies especially when coasting to a stop.
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02-23-2024, 06:16 PM	#3
MaximoSantiago Registered 0 Rep 2 Posts Drives: 2006 bmw 330i e90 Join Date: Oct 2023 Location: salt lake city utah iTrader: (0)	so, i had a bad vacuum leak from the ccv hose but i replaced it and it ran way better for a little but then had codes 2A2E 2A2F 2D06 they went away for a while after some driving then came back, i found these threads that sound like my same exact issue and symptoms https://www.e90post.com/forums/showt...highlight=2d06 https://www.e90post.com/forums/showt...=905209&page=2 https://www.e90post.com/forums/showthread.php?t=1113350 i replaced the maf connector yesterday and it drove perfect, idle was perfect, felt powerful up until it randomly stalled at a light with no warning, rough idle is back, same codes are back and im losing my mind i cleaned the connectors about to go back to my shop, i unplugged the maf and the car stayed running so maybe this maf already went bad? maybe lose ccv hose? 02 sensors? im about to go to my shop and clean the solenoids and hook up the good scanner, will update when i can
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