Rev Matching Issue

[bbnks2]

Originally Posted by Mach3M3

what discussion?

https://www.spool

&

street.com/threads/advanced-throttle-response-mystery.7721/

Then there is this one:
https://www.spool

&

street.com/threads/throttle-response-increase.5183/page-5

Looks like the thread originated on here actually... and n54 mhd has added a flash time option.

Don't think the same has been done on N55 yet... XDF needs to be defined and I doubt anyone did it for N52 given the smaller market. Seems like the N52 tunes are bare minimum tweaks not advanced DME reverse engineering and defining of all relevant tables. Maybe the above isn't relevant at all too idk but for sure there is some kind of logic at play.

[drunkenup]

Originally Posted by bbnks2

I thought it was the heavy DMFW too for a while but previous gen used DMFW too lol Throttle response of a 330i is amazing in comparison. Definitely some kind of dme logic to it.

The N54 guys are discussing something similar on spool & street right now related to doing a manual swap on a car and noticing that before flashing the DME the throttle response is raw and snappy. I just skimmed it earlier today and they were talking about about there being tuning to prevent driveline shock or something.

I had something similar happen to me when my RR corner wheel speed sensor went bad, the DME freaked out after driving on it a while and the throttle response became violent. Lots of driveline shock unless you were very gentle.

The new MHD 1M throttle option is better than stock but there is some room for improvement but AT THE TRACK this weekend I noticed I had perfectly good throttle response under hard braking. Until then, any ABS intervention meant almost dead throttle (only enough to hold the rpms its at) when trying to downshift rev match. I know it doesn't help anyone without an N54 but it suggests you should keep digging.

[bbnks2]

Originally Posted by drunkenup

I had something similar happen to me when my RR corner wheel speed sensor went bad, the DME freaked out after driving on it a while and the throttle response became violent. Lots of driveline shock unless you were very gentle.

The new MHD 1M throttle option is better than stock but there is some room for improvement but AT THE TRACK this weekend I noticed I had perfectly good throttle response under hard braking. Until then, any ABS intervention meant almost dead throttle (only enough to hold the rpms its at) when trying to downshift rev match. I know it doesn't help anyone without an N54 but it suggests you should keep digging.

Yeah when a wheel speed sensor goes bad all sorts of crazy happens. ABS seems to do some kind of traction control logic and the car will understeer like crazy trying to keep you rolling in a straight line. I had a wheel speed sensor go out on the way to autocross and tried to run the car... understeer everywhere and throwing up clouds of smoke form the front wheels locking up... and I run a more oversteer oriented setup. It sucked.

I am seriously considering doing an n54 swap just because of how stalled E-n55 tuning is... Can't be THAT hard, right?

[Mach3M3]

Originally Posted by Mach3M3

Still havent heard back from Bob at Stage FP about this...not sure what's happened to him, hopefully he's healthy and he still works there.

bumping this. Anyone heard back from Bob?

[spidertri]

Unfortunately, no.

[spidertri]

This turned into a pretty big issue for me yesterday at VIR. It was consistently happening into turn 1 and less consistently at turn 11. But, I was trying to work on my braking specifically and not getting an expected throttle blip was less than ideal.

[Phloozy]

Originally Posted by spidertri

This turned into a pretty big issue for me yesterday at VIR. It was consistently happening into turn 1 and less consistently at turn 11. But, I was trying to work on my braking specifically and not getting an expected throttle blip was less than ideal.

I'm glad others are experiencing this and I'm not going crazy. Getting to the bottom of this will be big so please share all the info you get!

[mad_hatter]

Stumbled onto this thread, and I had similar issues at an airport autocross event this summer. I had a couple issues going on:

1) I was pulling the shifter over too far on the 3-2 downshift and getting it into reverse. I can fix that by driving like less of a hack (and also buying a shifter with a reverse lockout, LOL)
2) I found the brake pedal does really weird things when I was HARD on it. Like it went extra hard and had no braking, did that a couple times. Really unnerving
3) During downshifts, I did notice I had to double blip to get the RPM I wanted out of the blip. This was in conjunction with issue #1 a couple times so I wrote it off to that. Co-drivers also experienced this same issue.

EBC yellow
200TW 245 tires
Unknown 3SIM tune (but no 3SIM )

[mindspin311]

Originally Posted by mad_hatter

Stumbled onto this thread, and I had similar issues at an airport autocross event this summer. I had a couple issues going on:


2) I found the brake pedal does really weird things when I was HARD on it. Like it went extra hard and had no braking, did that a couple times. Really unnerving

Sounds like ice mode. Typically happens when the REAR wheels lock up/ABS engages before the FRONT wheels do the same. When that happens the ABS pump will effectively lock you out like you experienced. Best you can do is jump off the pedal, wait a very quick moment, and get back on it.

[bbnks2]

Originally Posted by mindspin311

Sounds like ice mode. Typically happens when the REAR wheels lock up/ABS engages before the FRONT wheels do the same. When that happens the ABS pump will effectively lock you out like you experienced. Best you can do is jump off the pedal, wait a very quick moment, and get back on it.

I've never seen someone attribute this to the rears locking up. it has happened to me though and it is unnerving almost missing a turn because your brakes just go flat on you. Seems to be a rare occurrence and definitely has something to do with some kind of ABS issue but how do you know it has something to do with locking up the rears? I upgraded my rear brakes to M3 at one point without touching the fronts and still never had the rear brakes lock up.

But yeah when it happened to me I let off the pedal (after first panicking) and then got back into it and the pedal was stiff again. Luckily there is run off in turn 1 of Limerock to play with and keep it on track.

[mindspin311]

Originally Posted by bbnks2

I've never seen someone attribute this to the rears locking up. it has happened to me though and it is unnerving almost missing a turn because your brakes just go flat on you. Seems to be a rare occurrence and definitely has something to do with some kind of ABS issue but how do you know it has something to do with locking up the rears? I upgraded my rear brakes to M3 at one point without touching the fronts and still never had the rear brakes lock up.

But yeah when it happened to me I let off the pedal (after first panicking) and then got back into it and the pedal was stiff again. Luckily there is run off in turn 1 of Limerock to play with and keep it on track.

Ice mode triggers are more common on older cars. The car is in self-preservation mode. It knows that if the rear wheels are locked, then no matter how much you turn the wheel, the car won't steer. It will just slide. So it locks you out from making more braking inputs until things calm down.

Ice mode is rare, you have to do things just "right" to get it to engage. Happed to me in my Mini race car at Daytona. Big dip in the pavement entering T3 and I was fighting to wrangle it back in.

[Phloozy]

Talked to Stage FP and they said they are aware of the issue but do not have a solution for it If anyone finds out anything please update the thread.

[chris82]

Originally Posted by spidertri

I haven't experienced that at the track in my car. It's actually been fantastic on the brakes 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?

I turned off the other 3 you have here, but what's this one do?

DSC: Added C0C_DBC_MIN_AUSLOESEDRUCK min_pressure 00 value

[chris82]

Originally Posted by mindspin311

So I set in my driveway and gave the car all the pedal pressure I could and was able to rev it freely. Now my only thought is there was no wheel speed at the time, so maybe that changes things?

Originally Posted by Phloozy

Talked to Stage FP and they said they are aware of the issue but do not have a solution for it If anyone finds out anything please update the thread.

@phloozy Have you tried what mindspin311 did?

Also, @phloozy, did you code out all that brake crap like engine power cutting when brakes overheat, etc.?

[spidertri]

As I mentioned in post 20, coded brake settings have nothing to do with the issue Phloozy originally asked about. The issue is in the tune and only happens at-speed on track under the right conditions.

Originally Posted by chris82

I turned off the other 3 you have here, but what's this one do?

DSC: Added C0C_DBC_MIN_AUSLOESEDRUCK min_pressure 00 value

Dynamic Brake Control (DBC).
When, in an emergency, you apply the brake pedal quickly and with force but without really further increasing brake pressure, Dynamic Brake Control (DBC) instantly builds up maximum brake pressure, bringing your BMW more quickly to a halt.

https://www.1addicts.com/forums/show...&postcount=156

So, on track, this was happening to me where the car assumed I was emergency braking and would utilize all of the braking power, even though I didn't want it. So in a braking zone, I would end up much slower than expected by the time I got to the corner/apex/etc. Once I added the min value the car no longer intervenes.

[chris82]

Originally Posted by spidertri

As I mentioned in post 20, coded brake settings have nothing to do with the issue Phloozy originally asked about. The issue is in the tune and only happens at-speed on track under the right conditions.

Dynamic Brake Control (DBC).
When, in an emergency, you apply the brake pedal quickly and with force but without really further increasing brake pressure, Dynamic Brake Control (DBC) instantly builds up maximum brake pressure, bringing your BMW more quickly to a halt.

https://www.1addicts.com/forums/show...;postcount=156

So, on track, this was happening to me where the car assumed I was emergency braking and would utilize all of the braking power, even though I didn't want it. So in a braking zone, I would end up much slower than expected by the time I got to the corner/apex/etc. Once I added the min value the car no longer intervenes.

Thanks, I've definitely had this happen and it does exactly that, slows you down wayyy more than you wanted to

[Phloozy]

Originally Posted by spidertri

As I mentioned in post 20, coded brake settings have nothing to do with the issue Phloozy originally asked about. The issue is in the tune and only happens at-speed on track under the right conditions.

Dynamic Brake Control (DBC).
When, in an emergency, you apply the brake pedal quickly and with force but without really further increasing brake pressure, Dynamic Brake Control (DBC) instantly builds up maximum brake pressure, bringing your BMW more quickly to a halt.

https://www.1addicts.com/forums/show...;postcount=156

So, on track, this was happening to me where the car assumed I was emergency braking and would utilize all of the braking power, even though I didn't want it. So in a braking zone, I would end up much slower than expected by the time I got to the corner/apex/etc. Once I added the min value the car no longer intervenes.

Is this something I should be doing? I don't think I'm seeing over slowing issues but I do have to worry about getting into abs as I under a corner and the car will then push like crazy. I am pretty sure this is standard for bad braking while in abs though

[spidertri]

Phloozy I'm definitely not pushing as hard as you do, don't have the same grip level, but when first taking my car on track the brake pedal was so inconsistent that I worried I'd made a mistake thinking I could track the E82 reliably. DBC was the last brake setting that I changed and it made the pedal much more predictable and consistent, that was 2 years ago now and it's been great ever since.

[Phloozy]

Originally Posted by spidertri

Phloozy I'm definitely not pushing as hard as you do, don't have the same grip level, but when first taking my car on track the brake pedal was so inconsistent that I worried I'd made a mistake thinking I could track the E82 reliably. DBC was the last brake setting that I changed and it made the pedal much more predictable and consistent, that was 2 years ago now and it's been great ever since.

I'll have to look what I have mine set to. Can I change it in bimmer geeks protool? What exactly does it do?

[spidertri]

I changed mine using NCS Dummy but you can probably do it in protool. Changing the value to the min level reduces how much the car intervenes during emergency braking.

Stock, mine was Wert 01 value E4 and I had to add a line to make it Wert 01 value 00. The hexadecimal range is from 00 - FF, so the stock value is pretty far up the range.


Back to the thread topic, I was at CMP yesterday and had issues with throttle blip when braking for turn 11. On that track, turn 11 is at the end of the highest speed section and it's a heavy late braking zone. I just keep hitting the pedal with my heel until it blips.

[Phloozy]

Originally Posted by spidertri

I changed mine using NCS Dummy but you can probably do it in protool. Changing the value to the min level reduces how much the car intervenes during emergency braking.

Stock, mine was Wert 01 value E4 and I had to add a line to make it Wert 01 value 00. The hexidecimal range is from 00 - FF, so the stock value is pretty far up the range.


Back to the thread topic, I was at CMP yesterday and had issues with throttle blip when braking for turn 11. On that track, turn 11 is at the end of the highest speed section and it's a heavy late braking zone. I just keep hitting the pedal with my heel until it blips.

Being locked out of rev matching is now a badge of honor when tracking a 128 apparently lol Only happens when you start going fast!

[spidertri]

hassmaschine

Any chance you've seen anything in the N51/N52 DME file that prevents the brakes and throttle being applied at the same time but only when doing heavy braking?