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06-10-2021, 11:43 AM | #1 |
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Rev Matching Issue
I have been having issues on track where I cant seem to heel toe rev match under hard braking. I thought maybe it was a personal issue but then another friend with a 128 told me he was also having the same issues. On the street it heel toes fine but at the track its like the car kills the throttle under hard braking. I tried mashing the gas with my heel and still nothing.
I have done all the normal track coding but maybe there is something else I need to code out? Has anyone else experienced this and have input on what it can be? |
06-11-2021, 03:01 PM | #2 |
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I have experienced that on track as well, my brakes have otherwise been fantastic since I coded off:
- C0F_FLR ("Engine Power Reduction to Prevent Brake Overheating") - changed from wert_01 to wert_00 and wert_02 - C0F_FBS ("Brake Fading Compensation") - changed from wert_01 to wert_00 - C0F_BB_RAB "(Ready Brake Alert") - changed from wert_01 to wert_00 - DSC: Added C0C_DBC_MIN_AUSLOESEDRUCK min_pressure 00 value Before adding the last one I had a super weird brake pedal when hard on the brakes. It was distracting enough that I couldn't tell you if it was cutting throttle as well. Brakes are super consistent since then, using PFC08s and 200TW tires. Are you turning the TC off by holding the button down for ~5sec before you go on track?
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13 WK2 19 Alltrack S Last edited by spidertri; 08-02-2022 at 07:32 AM.. Reason: I have experienced this issue |
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06-11-2021, 06:04 PM | #3 | ||
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06-12-2021, 08:40 PM | #4 |
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It's not going to be a braking coding issue.
It will be a throttle safety coding/tuning problem. On the 135's we have an option we have to turn off to do good power braking burnouts. You'll be fine with a small brake press but once brake pressure passes some point, and I don't know what that point is, the computer kills the throttle. It's a safety measure, think Toyota and the 'unintended acceleration' debacle. Every electronic throttle vehicle has something similar now. So you'll have to look through the Brake computer and the DME to get it working best for you IMO. |
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07-08-2021, 06:33 AM | #5 |
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I found a video to demonstrate. In the video at 38 seconds watch the downshit into T5 of thunderbolt at NJMP. You can see the RPMs basically dont move from 5k rpm during the downshift. It seems to cut throttle because i am 100% hitting it with my heel, but it also prevents the car from clutch kicking it seems by holding the car at 5k rpm.
Last edited by Phloozy; 07-08-2021 at 07:12 AM.. |
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07-08-2021, 08:14 AM | #6 | |
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N54 platform released a "shift bog" fix which addresses torque limiter 2048. The same has not been done for N55 yet. I am sure the DME logic is the same as N52 dme in regard to torque limiters around shifting. It's brutal... time for a standalone. While I hate shifting slow... it is sometimes faster. Same with rev matching on the downshift. If you try to do it too fast it seems like nothing happens. Time your downshifts better so that you can roll into the gas over a slightly longer period of time for th rev match before slamming the next gear. Seems like the dme needs to see that split second of extra input to be happy. |
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07-08-2021, 08:21 AM | #7 | |
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07-08-2021, 08:32 AM | #8 | |
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There is no way it has anything to do with any brake coding that you could do. |
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07-13-2021, 07:17 AM | #9 | |
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I have been having really bad brake feel problems running ST43s and I think it's because they grab too aggressively for the ABS computer. It's so bad that I noticed wheels locking up at an autox i did with them. So I am switching to PFC08s hoping their release characteristics play nicer with the ABS cal on this car. |
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07-13-2021, 07:38 AM | #10 |
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E36 M3 pads shapes fit the 128 calipers (front and rear). The clips on the rears don't fit snugly in the rear piston though.
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07-13-2021, 07:46 AM | #11 | |
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I swapped back to stock pads for autox and did one wet event on them and the ABS engagement felt better, but it wasnt really the best testing conditions. |
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07-13-2021, 01:06 PM | #12 |
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I bet this is a throttle overlap issue (thanks Toyota.) It's because the car thinks the throttle is stuck and you're panic braking to try to overcome it. My car does this noticeably if I left foot brake with too much overlap, like putting some heat in the pads.
The way to see if this is the case is to lift on the brake, immediately reapply hard and see if you can blip. Once the computer realizes you're doing it on purpose it should let you overlap throttle and brake. |
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07-13-2021, 04:48 PM | #13 | |
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07-14-2021, 12:24 PM | #14 | |
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That said, I'm also not sure this is OPs issue, but it sounds like it. |
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07-15-2021, 10:19 AM | #15 |
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07-15-2021, 10:57 AM | #16 |
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I've noticed this too, when really pushing the car hard. On my 3 to 2 downshift, sometimes I have to wait till I let off some brake pressure before I get a good throttle blip. Figured it was some kind of safety delay or whatever, never knew I could code that out. Interesting...
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07-15-2021, 06:55 PM | #17 | |
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07-15-2021, 09:34 PM | #18 |
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I don't know of anything specific. I hadn't thought of the possibility of some kind brake/throttle overlap limit. More than likely it's my shoddy footwork, but if there is some intervention occurring, I'm interested in removing it. That's all. I'll probably do some testing and find out it's a talent issue.
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07-16-2021, 07:30 AM | #19 |
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07-16-2021, 08:09 AM | #20 |
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Yeah, sorry I probably confused the thread with the brake settings above. Definitely a different issue and one having to do with unintended acceleration.
Searching around it seems like a lot of different car makes are running into this at the track. I'll pay attention when I'm at the track in a few weeks and see if I can get it to happen. AutoX tomorrow but I doubt it'll happen there, hah.
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13 WK2 19 Alltrack S Last edited by spidertri; 07-16-2021 at 01:34 PM.. |
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07-16-2021, 10:46 AM | #21 |
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07-25-2021, 09:48 PM | #22 | |
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