01-07-2022, 02:11 AM | #1 |
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I have a 340ix 6speed manual. When accelerating moderately/heavily at highway speeds (70+ mph) in 5th or 6th gear, I feel some sort of hesitation or judder. I replaced my spark plugs and coil packs just in case.
It's not my clutch as that's been upgraded and my RPM's don't rise, but it feels something is slipping / traction related. Has anyone else experienced this? It's usually a single "hesitation" during a pull accompanied by a thud sound then it's smooth the rest of the pull. But today I experienced a few judders before something "caught" and then the rest of the pull was fine. I run square Michelin PS A/S 3+ with les than 10k miles on them. I'm pushing 520+ lb-ft of torque. A shop changed my transfercase fluid about 10k miles ago with OEM DTF-1 but unsure if they did a calibration. Is my transfercase on the way out or is it possible a calibration is what's needed? Maybe my rear tires are wearing faster than my fronts and are out of spec now? Thanks for all suggestions!
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2022 CT4-V Blackwing 6-speed
SOLD: 2016 340i xDrive 6-speed DAW v2.5 turbo E40 | Dorch S2 | VRSF DP | MST intake | AWE catback | 335is clutch | CSF heat exchanger | RK Autowerks intake manifold | Orange M Perf Brake Kit | KW Street Comfort coilovers | GTS taillights V2 |
03-15-2022, 02:59 PM | #4 |
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I'm on an upgraded turbo getting custom tuned and that seemed to help resolve the high gear/load and high speed judder. Funny how more power but a dialed in custom tune helped solve the issue. Not completely gone but it's way less noticeable now. Before I was on an OTS stage 2+ E30 tune.
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2022 CT4-V Blackwing 6-speed
SOLD: 2016 340i xDrive 6-speed DAW v2.5 turbo E40 | Dorch S2 | VRSF DP | MST intake | AWE catback | 335is clutch | CSF heat exchanger | RK Autowerks intake manifold | Orange M Perf Brake Kit | KW Street Comfort coilovers | GTS taillights V2 |
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03-16-2022, 12:55 PM | #5 |
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My car is an 8AT but I have a similar issue where I experience judder when accelerating hard at highway speeds (I think I've only noticed it above 50mph and above 3rd gear). I tried xDelete and that mitigated the problem completely which makes me think the problem is my transfer case. I don't want to keep my car RWD long term however so I changed the transfer case fluid, and while it didn't totally get rid of the issue it seems to have helped quite a bit (the judder is still there but it's way more subtle). I'll probably make a habit of changing the fluid every 20-30k miles.
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03-19-2022, 06:54 PM | #8 |
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03-20-2022, 03:11 PM | #10 |
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Yes - seems that's the only way and you just do your best to remove all the old fluid. It's odd, dealers don't seem to be willing to do this service - perhaps they don't have the instructions/tools/software to do the re-calibration of the transfer case clutches (like supposedly should be done)?
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03-28-2022, 06:38 AM | #11 |
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05-26-2022, 08:43 PM | #12 |
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Similar issue on my F31. Changed the fluid in the transfer case and solved the issue! $40 in Redline MT-90 fluid. Took me about an hour. Pretty easy to do. Recalibrated the accel system and runs smooooooth.
If your tires our more than 1% out of circumference ratio spec Front:Rear could create similar jutter under acceleration as your transfer case clutches try to compensate. Prolonged driving with such tire wear will eventually kill your transfer case. Hope you find a fix |
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05-27-2022, 06:26 PM | #13 |
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How does one recalibrate the accel system?
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06-01-2022, 04:34 PM | #14 | |
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10-08-2022, 12:10 PM | #15 |
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Thanks for this post guys. I just started having a weird thunk in 7th or 8th gear with light acceleration usually between 60 and 70mph. Seems similar to what G.Newt is describing. Has a thud and pause/slip and feels like I drove over a log or something. super brief, half a second thing.
I just made sure all of my tires are good pressure, the drivers sides were down 2psi compared to pass side. I ordered TC fluid to do that on Monday. Hoping that helps. I am stage 2 flex bm3 and xhp stage 3. I have reflashed the tunes and its still present. Under WOT or driving even somewhat medium throttle, there is never an issue. So strange. And normally i drive fairly light throttle, not bashing on the car all the time. Fingers crossed fluid change and tire pressures help. |
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