Constant speed fluctuation

E90PAT · 06-17-2016, 05:50 AM

Hey guys, noticed that with in 20-40 mph range, at constant speed, my car slightly fluctuates the rpm but maintains generally the same speed. I can feel the car slightly jolt forward every second in tandem with the rpm fluctuations. Any clues?

weehe126 · 06-17-2016, 07:08 AM

What is your car to start...

TBN54 · 06-17-2016, 07:33 AM

Are you due for plugs and coils?

E90PAT · 06-17-2016, 04:20 PM

Quote:

Originally Posted by weehe126

What is your car to start...

Sorry 335i

E90PAT · 06-17-2016, 04:22 PM

Quote:

Originally Posted by TBN54

Are you due for plugs and coils?

What's the average life of a coil? I'm 76k on a 08'

Hacksaw · 06-17-2016, 05:05 PM

I've seen them fail earlier than that mileage...... I always recommend people have a spare set of coils on hand.. unless you have extra vehicles on hand while you wait for parts.

I keep a spare set for my M3 for that very reason. I don't want to miss out on a track day because of a faulty coil.

E90PAT · 06-20-2016, 05:26 AM

I went to the shop this weekend and found out that I had a bad coil in cylinder six. After I replaced it, the car ran much better. However, the speed fluctuations Are still there

Socket · 06-20-2016, 07:28 AM

You may need a firmware update.

After months of an oscillating throttle it turned out to be a corrupted CAS module (probably from a failed flash) Once the CAS module was updated, no more problems

or it could be coils lel

http://www.e90post.com/forums/showth...ghlight=Harmsy

And the best news is that after the full firmware update of all modules, the oscillating issue seems to be gone too. It's just day 1, so i'll keep a close eye on it, but I'm really pleased to report the car is going well!

06-17-2016, 05:50 AM	#1
E90PAT SOFLO CODING 199 Rep 3,587 Posts Drives: Z4M Join Date: Apr 2009 Location: SoFla iTrader: (18)	Constant speed fluctuation Hey guys, noticed that with in 20-40 mph range, at constant speed, my car slightly fluctuates the rpm but maintains generally the same speed. I can feel the car slightly jolt forward every second in tandem with the rpm fluctuations. Any clues?
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06-17-2016, 07:08 AM	#2
weehe126 Brigadier General 1161 Rep 3,189 Posts Drives: 2017 340i Join Date: Apr 2014 Location: San Antonio iTrader: (2)	What is your car to start...
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06-17-2016, 07:33 AM	#3
TBN54 Captain 427 Rep 793 Posts Drives: 08' E92 335 -> 17' F30 340i Join Date: Dec 2015 Location: Upstate NY iTrader: (0)	Are you due for plugs and coils?
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06-17-2016, 05:05 PM	#6
Hacksaw Private First Class 25 Rep 116 Posts Drives: 2011 335i Join Date: May 2016 Location: SA TX iTrader: (0) Garage List 2011 BMW 335i [0.00]	I've seen them fail earlier than that mileage...... I always recommend people have a spare set of coils on hand.. unless you have extra vehicles on hand while you wait for parts. I keep a spare set for my M3 for that very reason. I don't want to miss out on a track day because of a faulty coil. __________________ '11 BMW///335i Sedan Black Sapphire Metallic\|Dakota Blk Lthr\|Sport Seats\|M Sport Sus PKG\|Nav\| '02 BMW ///M3Imola Red\|Blk Cloth\|6M\|TFS CSL TUNE - MSS54HP\|CSL Rep Airbox\|Euro Headers\|StopTech ST-40 BBKs\|Kirk 4pt Bar\|CF CSL Trunk\|GC Race F/R Sways\|
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06-20-2016, 05:26 AM	#7
E90PAT SOFLO CODING 199 Rep 3,587 Posts Drives: Z4M Join Date: Apr 2009 Location: SoFla iTrader: (18)	I went to the shop this weekend and found out that I had a bad coil in cylinder six. After I replaced it, the car ran much better. However, the speed fluctuations Are still there
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06-20-2016, 07:28 AM	#8
Socket Lieutenant General 4542 Rep 11,903 Posts Drives: 335i Join Date: Nov 2014 Location: Australia iTrader: (4) Garage List 2008 BMW E92 [0.00]	You may need a firmware update. After months of an oscillating throttle it turned out to be a corrupted CAS module (probably from a failed flash) Once the CAS module was updated, no more problems or it could be coils lel http://www.e90post.com/forums/showth...ghlight=Harmsy And the best news is that after the full firmware update of all modules, the oscillating issue seems to be gone too. It's just day 1, so i'll keep a close eye on it, but I'm really pleased to report the car is going well!
	Appreciate 0 Quote