09-09-2019, 04:19 PM | #1 |
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Bootmod3 - Need some help
Car: 2018 440xi GC, B58, non-MPPSK, automatic
Tune: BM3 Stage 2 91 oct Mods: ER Catless DP BM3 has been fantastic so far but there’s this odd scenario I keep encountering at highway speeds in sport mode, or city driving in 5th gear +. When the car is in Sport mode (by pressing the button, NOT by pulling the shifter to the left) and sitting in 5th gear at around 100-110km/h and I hit the accelerator, the car gives off what I can only describe as a droning sound and hangs in 5th for a second. it’s almost like it doesn’t want to leave 5th unless I WOT and then it’ll get to 6th but at a higher RPM. It doesn’t do this always but frequently enough that I’ve noticed it. Kinda similar in city driving as well. Comfort mode is keen in keeping the RPMs low and gear changes frequent. 5th gear at around 65km/h has what I can only describe as drone and the car rocks when I try to get it to 6th gear at around 70-75km/h. It’s like it can’t decide which gear to be in so it tries to keep me in 5th with this very subtle rocking of the RPMs. Has anyone had a similar experience? I’m not sure if I should do some data logs. I’m knew to tuning so if I should do some logs please let me know what gear(s) I should log cause I see conflicting information.
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09-09-2019, 06:48 PM | #3 |
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Sounds like you are lugging the engine. Not sure about the F30 automatics, but my E90 doesn't down shift unless you hit the kick down switch (basically you push it to wide open throttle). I feel a click when I hit the kick down switch. Otherwise you are lugging the engine, something the factory tune won't let you do because it doesn't wanna put the strain on the drive train. Welcome to tune life. Boot mod3 doesn't alter the transmissions calibrations, so it's essentially a mismatch in some sense.
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09-09-2019, 07:34 PM | #4 | |
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And I think it is impossible to “lug” the engine with the ZF8 as lugging indicates an “unhealthy” rpm range and the ZF downshifts if that happens. |
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09-09-2019, 07:38 PM | #5 |
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Do you have a transmission tune? Did you chose the BM3 Stage 2 with reduced torque so that the ZF stock limit is not triggered? Wild guess you chose the not torque limited option and open throttle at low rpm produces a torque spike hitting the ZF factory limits and the transmission and the ECU panic
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09-09-2019, 09:02 PM | #6 | |
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BMW has that kick down switch automatic transmissions thing they do, I dunno why probably something lame like MPG or emissions. Just click down a gear or two or just pedal to the metal and let the transmission shift. https://www.roadandtrack.com/car-cul...ad-for-engine/ |
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09-09-2019, 09:06 PM | #7 |
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This thread is pointless without logs. But yes, I agree you should log and file a support ticket with PTF. They'll be able to tell you what's up. Also some of us here can read logs and can give you a general idea of what's going on.
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09-09-2019, 09:20 PM | #8 | |
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09-10-2019, 07:00 AM | #9 | |
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And torque at low rpm being a problem? Look at a Diesel engine and how it develops torque and you see that the same transmission in the same car with a Diesel engine has to “suffer” higher torque stock. The problem is again mostly with stick or fully manual auto as in case of WOT the trans wouldn’t downshift but stay in the rpm range which has the highest torque ..... Last edited by marcthedark; 09-10-2019 at 07:05 AM.. |
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