F30 N55 8th gear engine rpm too low at highway speed?

Wires · 01-15-2019, 09:22 PM

Are you sure it's a "real" issue and not an Active Sound issue?

If you go into sport mode, you should be able to upshift back into 8th gear. I run manual mode + sport 100% of the time and have no issues. 8th gear all the time, even climbing large grades there isn't much difference in the dash's reported mileage between 7th and 8th (other than 7th revs "higher", and 8th has more of a active sound drone like it's working).

6th gear is "drive", 7th and 8th are "overdrive" for better mileage.

Sanko · 01-15-2019, 10:00 PM

Quote:

Originally Posted by Carbon_F30

Quote:

Originally Posted by Blocke

Odd question- have you noticed a correlation to the symptom and the AC being on or off? I had a similar issue when the AC was on and the engine was lugging as you describe. It turned out to be Low frequency vibration bleeding into the cabin via an AC line. There is an older TSB for it. Took it to dealer and the fix was to install a $5 weighted collar around the line to dampen the noise. Haven't heard it since. Just a thought.

So I haven't gone to the dealership to get the actual weighted dampener that BMW sells but I went to Home Depot and bought a small weighted door hinge thing (ghetto I know lol) and zip tide it to the AC hose. I'll be dammed but it seemed like it worked. I could still hear the noise but it was substantially dampened and didn't sound at all like the engine was lugging in a high gear at a low rpm. The sound was definitely still there but just way less noticeable so I'm hoping that really was the fix.

My local BMW dealer actually has that weighted dampener in stock so I'm just gonna spend the 9 bucks and buy it and install it myself and see if it does better or worse than my ghetto quick fix.

Appreciate all the responses guys!

Can you explain or show it in a picture where is it exactly?

chiefneil · 01-16-2019, 08:57 AM

I cruise on the highway in comfort mode on all the time with no issues at all in the 70-80mph range. Can’t say that I pay much attention to the rpm, but definitely no odd sounds and nothing remotely similar to engine lugging. I have the exact same car as the OP - 2014 335i.

When the car was new I did have the issue with the hose knocking resonance. It sounded like rattling at a very specific rpm, but it was a very different sound from lugging. Lugging to me sounds like more of a slow paced rumble accompanied by that distinct feel you get of the drivetrain struggling, while the resonance sound was clearly a rattle like other old-timers might’ve heard in an older carbureted car with bad gas in need of a valve job, or marbles in a coffee can.

01-15-2019, 09:22 PM	#23
Wires Brigadier General 1646 Rep 4,877 Posts Drives: 2016 340i xDrive Join Date: Apr 2008 Location: Calgary iTrader: (0)	Are you sure it's a "real" issue and not an Active Sound issue? If you go into sport mode, you should be able to upshift back into 8th gear. I run manual mode + sport 100% of the time and have no issues. 8th gear all the time, even climbing large grades there isn't much difference in the dash's reported mileage between 7th and 8th (other than 7th revs "higher", and 8th has more of a active sound drone like it's working). 6th gear is "drive", 7th and 8th are "overdrive" for better mileage.
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01-16-2019, 08:57 AM	#25
chiefneil Lieutenant Colonel 772 Rep 1,502 Posts Drives: 2014 335i M-Sport Join Date: Sep 2013 Location: Arizona iTrader: (0)	I cruise on the highway in comfort mode on all the time with no issues at all in the 70-80mph range. Can’t say that I pay much attention to the rpm, but definitely no odd sounds and nothing remotely similar to engine lugging. I have the exact same car as the OP - 2014 335i. When the car was new I did have the issue with the hose knocking resonance. It sounded like rattling at a very specific rpm, but it was a very different sound from lugging. Lugging to me sounds like more of a slow paced rumble accompanied by that distinct feel you get of the drivetrain struggling, while the resonance sound was clearly a rattle like other old-timers might’ve heard in an older carbureted car with bad gas in need of a valve job, or marbles in a coffee can.
	Appreciate 0 Quote