Acceleration Issue

E90_Okie · 03-20-2019, 02:27 PM

2009 335i MT

Cranks - Great
Idles - Great
Overall Engine Vibration with issue - Awesome
Shifts - Great

Issue: 2800-4000 RPM acceleration with greater than 1/4 throttle
Engines Cold or Hot

Video of RPM drop

When I accelerate more than 1/4 throttle (roughly) and hit somewhere between 2800-4000 RPM depending on RPM, my RPMs drop 500-1000 RPM. It drops smoothly like I was shifting gears and slowly climbs back up. I can be cruising in 6th gear at 2500RPM and if I gently apply throttle I can accelerate slowly with no issue. Once I’m above 4500 RPM, I can accelerate harder with zero issues.

I’ve read several reviews to running fuel system cleaner and run at 4000 RPM 3rd/4th gear on the highway for 20 minutes and then shift to 6th to cool down.

However, I did find one individual who mentioned something similar and that the issue ended up being engine harmonics caused the charge pipe to leak between 2500-4000 RPM from a slightly damaged o-ring from the factory install. BMW NA covered the service once found. The guys vehicle was out of warranty.

What do you guys think?

I can easily do the work but I don’t want to be chasing ghosts.

03-20-2019, 02:27 PM	#1
E90_Okie BMW Motorcycle Technician Level 1 0 Rep 2 Posts Drives: 2009 E93 Black on Black Join Date: Jan 2017 Location: Oklahoma iTrader: (0)	Acceleration Issue 2009 335i MT Cranks - Great Idles - Great Overall Engine Vibration with issue - Awesome Shifts - Great Issue: 2800-4000 RPM acceleration with greater than 1/4 throttle Engines Cold or Hot Video of RPM drop When I accelerate more than 1/4 throttle (roughly) and hit somewhere between 2800-4000 RPM depending on RPM, my RPMs drop 500-1000 RPM. It drops smoothly like I was shifting gears and slowly climbs back up. I can be cruising in 6th gear at 2500RPM and if I gently apply throttle I can accelerate slowly with no issue. Once I’m above 4500 RPM, I can accelerate harder with zero issues. I’ve read several reviews to running fuel system cleaner and run at 4000 RPM 3rd/4th gear on the highway for 20 minutes and then shift to 6th to cool down. However, I did find one individual who mentioned something similar and that the issue ended up being engine harmonics caused the charge pipe to leak between 2500-4000 RPM from a slightly damaged o-ring from the factory install. BMW NA covered the service once found. The guys vehicle was out of warranty. What do you guys think? I can easily do the work but I don’t want to be chasing ghosts.
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