335i....strange surging feeling on the highway? - N54Tech.com

iqraceworks · **335i....strange surging feeling on the highway? -** 07-08-2020, 10:52 AM

I was driving home the other day on the highway...constant speed (75mph), on flat road. I started feeling a weird pulse, or split second lack of power from the motor....almost like a missfire. You could just barely feel it......it would do it about ever 3-4 seconds. It was almost like you just killed the ignition for a few milliseconds....just enough to feel it, but not really enough to affect anything. It did this for a few miles, and then I pulled over to plug my cable in so I could pull a log.

Got the cable hooked up, and MHD logging....got back on the highway, everything is normal again (crap!). I checked the log when I got home........everything looked fine. No faults, no codes.

Any idea what would cause something like that? A failing injector? Failing LPFP or HPFP? Missfire? Vanos issue?

No codes where saved, and the car has new plugs and coils as of a few months ago. I did a wide open throttle 2-3gr pull...and everything looked fine except my LPFP is starting to get weak.

Any ideas?
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fredcase · 07-08-2020, 10:57 AM

Running Burble?

sliebhard · 07-08-2020, 11:16 AM

I have this occasionally and I have to reset my throttle adaptation. I know that hasn't always worked for others though.

YMMV

iqraceworks · 07-08-2020, 11:23 AM

Thanks I might give that a try. I'm hoping that when/if it does it again ...I can run a log and see what's going on. Very weird issue......almost like you turned the ignition off for a few milliseconds. Even with the cruise control off it did it.....and it wasn't just random, it was a constant blip I'd power loss about every 3-4 seconds....over and over.

But after pulling over for a minute, and getting back on the highway....it was all back to normal.

ewicky · 04:21 PM

After ruling out other obvious causes, my research has uncovered this can (apparently) also be caused by a worn torque converter lockup or intake in need of walnut blasting.
Edit: because my car also does this sometimes. driving in M6 (manual mode) fixes the issue. So it must be that the torque converter lockup is too loose in automatic mode and slips or something.

iqraceworks · 07-10-2020, 04:52 AM

Quote:

Originally Posted by ewicky

After ruling out other obvious causes, my research has uncovered this can (apparently) also be caused by a worn torque converter lockup or intake in need of walnut blasting.
Edit: because my car also does this sometimes. driving in M6 (manual mode) fixes the issue. So it must be that the torque converter lockup is too loose in automatic mode and slips or something.

D6 and M6 should be the exact same gear.......I don't think TQ lockup varies between the two.

ewicky · 07-10-2020, 09:36 AM

Quote:

Originally Posted by iqraceworks

D6 and M6 should be the exact same gear.......I don't think TQ lockup varies between the two.

I can't speak to your xHP tune, but I have one of the Alpina B3 flashes and the algorithm/points for torque converter lockup is entirely different between D6 and M6. I can feel the difference.