Revs hunting

NZ-M340ixDrive · 06-17-2020, 03:45 PM

Just wondering what the issue is.
It's idling sub 1000rpm but hunting between 700-800rpm with the needle moving up and down slightly. Temp is sub 100c but above 70c

technician117 · 06-21-2020, 11:03 AM

Quote:

Originally Posted by Benji335i

Just wondering what the issue is.
It's idling sub 1000rpm but hunting between 700-800rpm with the needle moving up and down slightly. Temp is sub 100c but above 70c

Could be a ton of things especially since your car isn't stock and has a tune. Might not even be anything wrong. How often has it done it? More interested in if it repeats even after new cold starts for the day.

Maybe check your fuel trims to start.

Boosted M5 · 06-21-2020, 08:18 PM

Mine does the same thing. Been tuned for a while can't remember if it did it before the tune or not. I imagine that it may be due to the fact that I still have the cold start active and no cats.

NZ-M340ixDrive · 06-21-2020, 08:30 PM

Quote:

Originally Posted by Boosted M5

Mine does the same thing. Been tuned for a while can't remember if it did it before the tune or not. I imagine that it may be due to the fact that I still have the cold start active and no cats.

Quote:

Originally Posted by technician117

Quote:

Originally Posted by Benji335i

Just wondering what the issue is.
It's idling sub 1000rpm but hunting between 700-800rpm with the needle moving up and down slightly. Temp is sub 100c but above 70c

Could be a ton of things especially since your car isn't stock and has a tune. Might not even be anything wrong. How often has it done it? More interested in if it repeats even after new cold starts for the day.

Maybe check your fuel trims to start.

It ended up being a dirty maf. Checked the trims and is was running too rich!
STFT were hovering around 0.75-0.85 now after cleaning the mafs they are between 0.96-1.06

Quote:

Originally Posted by Boosted M5

Mine does the same thing. Been tuned for a while can't remember if it did it before the tune or not. I imagine that it may be due to the fact that I still have the cold start active and no cats.

This was the first time my car did this. Which was weird but all fixed now

technician117 · 06-22-2020, 05:33 AM

Thanks for the update with resolution. Every data point helps when someone is trying to diagnosis a similar problem.

06-17-2020, 03:45 PM	#1
NZ-M340ixDrive Private First Class 27 Rep 124 Posts Drives: 2020 M340i xDrive Join Date: Apr 2017 Location: Auckland iTrader: (0) Garage List 2020 BMW M340i xDrive [0.00]	Revs hunting Just wondering what the issue is. It's idling sub 1000rpm but hunting between 700-800rpm with the needle moving up and down slightly. Temp is sub 100c but above 70c __________________ 335i DCT - Sold M5 DCT - Sold M140i Top mount big single - RIP M340i xDrive Top Mount big single in the works
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06-21-2020, 08:18 PM	#3
Boosted M5 Private First Class 69 Rep 193 Posts Drives: F10 m5 Join Date: Dec 2018 Location: Sf bay area iTrader: (0)	Mine does the same thing. Been tuned for a while can't remember if it did it before the tune or not. I imagine that it may be due to the fact that I still have the cold start active and no cats.
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06-22-2020, 05:33 AM	#5
technician117 Captain 251 Rep 606 Posts Drives: 2000 M5, 2001 M5, 2013 M5 6MT Join Date: Jul 2018 Location: Buffalo iTrader: (1) Garage List 1990 BMW M5 [0.00] 2000 BMW M5 [0.00] 2013 BMW M5 [0.00]	Thanks for the update with resolution. Every data point helps when someone is trying to diagnosis a similar problem.
	Appreciate 1 NZ-M340ixDrive26.50 Quote