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Author Topic: 1.8t change rev limiter strategy (bouncing rev limiter)  (Read 1170 times)
ratosluaf
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« on: May 31, 2023, 01:51:23 AM »

Stock limiter sounds awful. Is there any solution to prevent throttle cut on rev limiter and make it bounce like in non-dbw car? I don't want any spark cut, just regular fuel cut without cutting throttle.

Thought about using KFLF map and using multiplier 0 or near 0 on last rpm row, then resume fuel 50rpm earlier, like hard cut. This would involve setting temin and teminva to 0, any other maps? Also thing that worries me - as I read in FR, KFLF is used only in part-throttle conditions, so it can not work during WOT.

Are there any other ways to do so? Tried setting DNMAXH to 50 but still it sounds awful. Just don't like the idea that on rev limiter there is throttle intervention and throttle shutdown to ~40%.

Attaching bin and xdf
ECU ID is 4B0 906 018 DH
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James1
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« Reply #1 on: May 31, 2023, 04:41:00 AM »

KFLF is used all the time, it's meant for tuning part throttle but is a throwback from earlier ECU's.

Better to use FKKVS
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ratosluaf
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« Reply #2 on: May 31, 2023, 04:56:14 AM »

KFLF is used all the time, it's meant for tuning part throttle but is a throwback from earlier ECU's.

Better to use FKKVS

Would anything differ if I use KFLF instead of FKKVS? KFLF is unused in my binary (all set to 1s) so I wanted to change axes and use it strictly for fuel cut. Don't want to use FKKVS because i use it to correct fueling with non oem injectors.

Besides of that, would it even work?
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prometey1982
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« Reply #3 on: June 01, 2023, 12:41:27 AM »

Would anything differ if I use KFLF instead of FKKVS? KFLF is unused in my binary (all set to 1s) so I wanted to change axes and use it strictly for fuel cut. Don't want to use FKKVS because i use it to correct fueling with non oem injectors.

Besides of that, would it even work?
He suggested to set FKKVS values to 0 in regions where you don't need fuel. But you need to do it realy carrefully. I.e. you need to set last two RPM rows to something like 6000 and 6001. In 6001 cells should be zeroed. And 6000 cells should be set as you want. In such case when engine's speed exceed 6000 RPM injection will be disabled.
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prj
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« Reply #4 on: June 01, 2023, 01:42:11 AM »

Toggling between a 5 cylinder cut and 0 cylinder cut will work and sound like complete shit.
Only horrible ideas in this thread.

All OEM limiters even since the very early Motronic ECU's use a sequential rotating cut pattern.
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ratosluaf
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« Reply #5 on: June 01, 2023, 02:52:39 AM »

Ok so is there any other way to make rev limiter more like non-dbw car, more bouncy at limit, but without turning off torque monitoring or anything like that? I assume that req load at limiter is hardcoded, but maybe I am wrong?
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prj
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« Reply #6 on: June 01, 2023, 03:06:30 AM »

Yes of course there is a way, modify the firmware to do what you want. Write some assembly code to set redsol progressively based on nmotpr_w.

If you mean by changing some maps - no. Nothing you are going to do on this ECU in the cal area is going to give a good result.
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ratosluaf
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« Reply #7 on: June 02, 2023, 01:52:35 AM »

that's way too much effort since i know nothing about what i need to get done.

pita
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