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      04-24-2019, 01:17 PM   #1
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Throttle response issue - interesting log

I'm at a bit of a loss here, so I'm reaching out to the community to see if anyone has ever seen similar behavior. If you search for "N54 throttle response" you will get a ton of people complaining about it, but I've yet to see anyone with a similar issue as mine.

The problem that I'm trying to solve is a massive throttle lag that makes the car feel extremely slow to react to accelerator pedal input. The following data shows that the car CAN, when software/sensors allow, react blazingly fast to accelerator pedal position. But it doesn't.

Car is E82 135i, 2007, MT, with MSD80 running I8A0S (not sure what the native version was).

No load to the engine, this behavior is logged with the car coasting on neutral and the only difference is clutch pedal either being up or down. This behavior does not exhibit itself when the car is at standstill. throttle response is immediate at standstill regardless of clutch pedal position.

The delayed throttle response is present always when driving the car, the only way to get the throttle to respond quickly is to press down the clutch pedal and then work the accelerator pedal. Therefore, as this is MT, rev-matching downshifts accurately is possible.

So, the following behavior can and has been logged:

clutch pedal pressed, gear neutral
  • gear reads correctly in logs
  • throttle response with accelerator pedal press is immediate
  • rpms respond immediately
  • boost target is raised
  • wdgc can react upwards, up to 100

clutch pedal raised, gear neutral
  • gear reads incorrectly in logs
  • throttle response with accelerator pedal press is delayed
  • rpms respond sluggishly
  • boost target is 0
  • wdgc reacts downwards or minimally upwards

And here is a log of the behavior: https://datazap.me/u/works/throttle-...og=0&data=2-25

First three rev ups are with clutch pedal raised, the next three clutch pedal pressed. You can clearly see that with a similar accelerator pedal position the throttle opens either super fast and RPM's climb quick which leads to me releasing the accelerator pedal, or when the clutch pedal is raised the throttle opens slowly + only a little and the RPMs raise slower which leads me to keep the accelerator pedal pressed for longer.

I've replaced both MAP sensors and the throttle body assembly. The car is stage 1 turbo +fbo +flexfuel. Clutch delay valve has been deleted and the clutch is from 550i, not sure if either of those are somehow involved in this. To me this looks like a sensor or software issue as the throttle response can be amazingly fast when the clutch is disengaged and pedal is down or the car is stationary.

Do note that resetting adaptations does nothing to alleviate this. I've tried several different software versions from two tuners and the problem persists. So that puts more weight on this being a sensor issue. But which one?

I sincerely hope that some of you brainy people can shed some light on this and come up with solutions for me to try out.
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      04-24-2019, 03:01 PM   #2
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Something seems off, why is your Lambada so high ? are you crusing with your foot off the pedal ? There is a point where ACCEL position is at 34% but the lamabda are still set to infinite (234.95, seems odd)
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      04-24-2019, 03:22 PM   #3
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Thanks for taking a look!

Quote:
Originally Posted by Stealthbombing View Post
Are you cruising with your foot off the pedal?
Yea, as stated in the original: "No load to the engine, this behavior is logged with the car coasting on neutral."

Quote:
Originally Posted by Stealthbombing View Post
Something seems off, why is your Lambada so high ? There is a point where ACCEL position is at 34% but the lamabda are still set to infinite (234.95, seems odd)
That is indeed odd behavior, but for two ticks. How reliable are these logs sync at that resolution? And if it is indeed odd, what is it the symptom of?

Additionally I'm looking the logs through more, even "load request" lags behind when the clutch is up.
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      04-24-2019, 08:12 PM   #4
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Looks like a software feature to me. Requested load is way higher with the clutch depressed. Probably for rev-match like you mentioned.

For the gear thing, I wonder if the software just uses rpm versus wheel speed. Your gear moves down when revs climb. There is a clutch pedal sensor but no gear position sensor as far as I know. So when the clutch is down, it knows you are not "in gear".

Can you record cam positions?
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      04-24-2019, 08:22 PM   #5
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Quote:
Originally Posted by Stealthbombing View Post
Something seems off, why is your Lambada so high ? are you crusing with your foot off the pedal ? There is a point where ACCEL position is at 34% but the lamabda are still set to infinite (234.95, seems odd)
The raster rate is 0.12 seconds which is very slow. You also have the fact that he just came out of fuel cut-off to a fast throttle stab, and the lag for the sensor to read the oxygen level.
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      04-25-2019, 02:33 AM   #6
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I did post this question to few other forums as well and got this interesting reply elsewhere:

"My car does the same thing. I believe this is designed behavior by BMW to smooth out throttle inputs and make the car feel more "luxurious."

I know on E46s, the same feature was called anti-jerk, and could be disabled through tuning. I haven't been able to find any tables to do so within MSD8X, but there's a chance they exist somewhere.

As you observed, the throttle smoothing only activates while the car is moving and the ECU sees the clutch pedal up. I wired in a switch that interrupts the clutch switch wire to the ECU to get around this. When I interrupt the signal, the ECU defaults to seeing the clutch pedal as down, and does not activate the throttle smoothing in any scenario. Downside is, you lose gear detection, and therefore boost by gear won't work. Also, cruise control won't work, but since I have a switch, I can just flip it back on if I need either of those. Beyond that, I have noticed no negative effects. The car just feels much more responsive, and in my opinion, a lot more fun to drive."

Sounds like I'll have a weekend wiring project ahead of me for the next step to try out.
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      04-25-2019, 02:03 PM   #7
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The tables exist and have apparently been found. Better values need to be copied in from the 1M which apparently doesnt have this "feature"
Its still unknown if the DCT cars have the same table and if so, activating sport mode in those cars does the same thing to an extent.
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      04-25-2019, 02:24 PM   #8
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Quote:
Originally Posted by Aus335iguy View Post
The tables exist and have apparently been found. Better values need to be copied in from the 1M which apparently doesnt have this "feature"
Its still unknown if the DCT cars have the same table and if so, activating sport mode in those cars does the same thing to an extent.
Do you have any idea who I can bug to get details/definitions for those tables and pass the info to my tuner to take a look?
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      04-25-2019, 03:05 PM   #9
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Quote:
Originally Posted by Works View Post
Quote:
Originally Posted by Aus335iguy View Post
The tables exist and have apparently been found. Better values need to be copied in from the 1M which apparently doesnt have this "feature"
Its still unknown if the DCT cars have the same table and if so, activating sport mode in those cars does the same thing to an extent.
Do you have any idea who I can bug to get details/definitions for those tables and pass the info to my tuner to take a look?
I think the people involved and who discovered it are keeping it to themselves. The point is that it does exist, can be found and so therefore can be found again.
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      04-25-2019, 03:07 PM   #10
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Quote:
Originally Posted by Works View Post
Quote:
Originally Posted by Aus335iguy View Post
The tables exist and have apparently been found. Better values need to be copied in from the 1M which apparently doesnt have this "feature"
Its still unknown if the DCT cars have the same table and if so, activating sport mode in those cars does the same thing to an extent.
Do you have any idea who I can bug to get details/definitions for those tables and pass the info to my tuner to take a look?
I think the people involved and who discovered it are keeping it to themselves. The point is that it does exist, can be found and so therefore can be found again.
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      04-25-2019, 03:17 PM   #11
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Quote:
Originally Posted by Aus335iguy View Post
I think the people involved and who discovered it are keeping it to themselves. The point is that it does exist, can be found and so therefore can be found again.
I never really completely understood the mindset that some people have regarding not sharing information that they are not going to use for business reasons. Each to their own I guess, I'd share that in a heartbeat considering how many people are seeing this "feature" as a hindrance. If this could be optioned in during a flash with MHD, like linear throttle, it'd be perfect.
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      04-25-2019, 04:43 PM   #12
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Let us know if you try the switch trick on the clutch sensor.

Concerning a feature like that in MHD flash options, it would be awesome.
It could be something you can ask directly at MHD.

It's also a possibility that some tuners that makes custom map are aware of this feature.

Too bad I just read that you cannot flash the 1M map on a regular N54, there are too many different tables.
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      04-26-2019, 01:11 AM   #13
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Quote:
Originally Posted by studio54 View Post
Let us know if you try the switch trick on the clutch sensor.

Concerning a feature like that in MHD flash options, it would be awesome.
It could be something you can ask directly at MHD.

It's also a possibility that some tuners that makes custom map are aware of this feature.

Too bad I just read that you cannot flash the 1M map on a regular N54, there are too many different tables.
The 1M flash can be used on a regular n54 its just its not as easy to get on to a standard car. There's a few things that have to be done custom and people aren't sharing that either
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      04-26-2019, 04:38 AM   #14
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Quote:
Originally Posted by studio54 View Post
Let us know if you try the switch trick on the clutch sensor.

Concerning a feature like that in MHD flash options, it would be awesome.
It could be something you can ask directly at MHD.

It's also a possibility that some tuners that makes custom map are aware of this feature.
I’m doing all three already When I get the hardware in the near future I’ll wire in the switch for signal 2 wire and will then report back unless software options are already available.

I did ping yesterday my tuner as well as emailed a feature request to MHD to two different addresses with links to this and my other threads. As MHD is full-on with B58 I’m not holding by breath to get this implemented in the near future, but if they did, that way the entire community could get in on this. Which for an old platform like N54 would be the optimal course. Sharing is caring, etc.

So I’ll either fix this with hardware only for me, or my tuner makes it work only for me which is ideal for me but then everyone else gets left behind. Best course of action would be for MHD to step in and implement this as a checkbox/option in the flash options.

All in all I’m super stoked to get this massive annoyance taken care of and I know what to do. Best of all I have an option where I’m not relying on anyone else to get this fixed. Eff yes.
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      04-26-2019, 08:33 AM   #15
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Got a response from MHD and they are not interested. I did ask if they could fill me in with details on how to fix it in software as they seem to know, but apparently most of their users lean on the ”smooth” throttle. I’m waiting for a follow-up reply.

I understand why this smooth application works for some, but not for all. And definitely it does not work for me.

Hardware is always a solution unless my tuner can come through.
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      04-26-2019, 03:12 PM   #16
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Quote:
Originally Posted by Works View Post
Got a response from MHD and they are not interested. I did ask if they could fill me in with details on how to fix it in software as they seem to know, but apparently most of their users lean on the ”smooth” throttle. I’m waiting for a follow-up reply.

I understand why this smooth application works for some, but not for all. And definitely it does not work for me.

Hardware is always a solution unless my tuner can come through.
Here you go, the throttle tables are going to be released. They are currently being tested.
https://www.bimmerpost.com/forums/sh...php?p=24705921
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      04-26-2019, 05:32 PM   #17
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Quote:
Originally Posted by Aus335iguy View Post
Here you go, the throttle tables are going to be released. They are currently being tested.
https://www.bimmerpost.com/forums/sh...php?p=24705921
Isn't this a coincidence then! Happy days!
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      04-26-2019, 06:56 PM   #18
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Sounds promising

So if i understood, assuming i do not have any special knowledge in this, it could be a future feature that i could ask at a custom tune tuner ?
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      04-26-2019, 08:42 PM   #19
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Originally Posted by studio54 View Post
Sounds promising

So if i understood, assuming i do not have any special knowledge in this, it could be a future feature that i could ask at a custom tune tuner ?
It appears that way
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      04-30-2019, 09:01 AM   #20
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Quote:
Originally Posted by Works View Post
Got a response from MHD and they are not interested.
Strike that, it seems that MHD was thinking that I meant throttle mapping/sensitivity and not pedal -> throttle plate opening lag. After a bit further discussion they definitely are interested and might already be in contact with vtl and co who discovered this.

I checked in with my tuner as well who told me that, at least previously, integrating this behavior from IK (1M) rom to IJ/MSD81 or I8/MSD80 would be close to impossible as IK is so vastly different in internal construction than the two others.

If the vtl method to fix this issue is not only the maps, but the functionality as well between IK and IJ/I8 then they would appear to have found something novel and be able to finally fix this shit throttle filtering that has plagued all MT cars for all eternity.

I'm anxiously waiting for a result
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      04-30-2019, 11:10 AM   #21
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Quote:
Originally Posted by Works View Post
Strike that, it seems that MHD was thinking that I meant throttle mapping/sensitivity and not pedal -> throttle plate opening lag. After a bit further discussion they definitely are interested and might already be in contact with vtl and co who discovered this.

I checked in with my tuner as well who told me that, at least previously, integrating this behavior from IK (1M) rom to IJ/MSD81 or I8/MSD80 would be close to impossible as IK is so vastly different in internal construction than the two others.

If the vtl method to fix this issue is not only the maps, but the functionality as well between IK and IJ/I8 then they would appear to have found something novel and be able to finally fix this shit throttle filtering that has plagued all MT cars for all eternity.

I'm anxiously waiting for a result
Great ! Waiting too
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      05-02-2019, 01:20 PM   #22
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In case someone later on reads this up, the potential solution to this problem is discussed in the following thread:

https://www.e90post.com/forums/showthread.php?t=1610143
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