MHD E50 timing dip @low rpm under WOT

[vadonchez]

not on my car, i took a look to a lot of other N54 people log and timing on v10 or v9 map seem's to be ok.
But you're right, custom tune is the best but i would like to keep the possibility to switch map quickly id needed.
I don't know if it's possible to make multimap works with custom tune.

 

[carabuser]

Yes multi maps do work on custom tunes.

 

[vadonchez]

Hi guys


I finally decided to send an email @Ken who made MHD maps to talk about my timing dip problem with him.

He told me that problem could come from a torque problem between DME and TCU and advised me to install XHP stage3 first wich can help.


Because of mixed review about XHP on this and other forum (somebody are really appy with it when other people say that it's unuseful and don't worth money ) I didn't want to buy it.


But Ken advice XHP to me and Ken is not everybody in N54 tuning world ....

So, I bought XHP 3 days ago and installed stage3 map on my Z4 35IS.


Then I loaded V10 stage 1+ map and went for a road test.

Unfortunately, timing dip was still here...But postshift timing drop was less here, that's the first good point!


I sent another email @KEn to gave him some news about my last update and he told me to try other transmission choice into MHD app. I was surprised because I'm DCT so I chosed DCT but he said "try all the transmission choise, MT, AT, AT+XHP and see if one works better and can solve your problem"


Ok you're the boss Ken!


So today, after tried MT parameter (wich doesn't work fine) I tried V8 1+ with AT+XHP and saw that even if timing dip where always here, they were here less often.

This morning I finally tried V9 1+ E50 with "AT+XHP" parameter in MHD MAP.

I went for some runs and logs, and timing dip @low RPM totally disappear!!

V9 log with XHP stage3 and AT+XHP MHD parameter

Still have some postshift timing drop but less than before and Ken said to me that I have to accept that and enjoy the car.

To be honnest, car pulls very smooth and power is here for sure!!

Here is my feedback for those who have the same problem than me.

Ragards

 

[wheela]

Glad you got it sorted! I haven't heard anything negative about xhp when compared to stock transmission tunes - is this what you found, or were they comparing xhp OTS tunes to custom transmission tunes? Granted I'm not dct (6hp), but xhp completely transformed my driving experience for the better.

 

[vadonchez]

I was actually speaking about XHP returns for DCT cars.

Maybee I'm wrong but I remember that carabuser was disapointed for example, somebody said that shifts aren't really quicker, that gear changes rpm wasn't optimum, that quick downshift when stoping quickly at a STOP was not ok etc....but maybe it was on older XHP revision, they keep updating so problem reported by users should have been resolved.


Personnaly, i drove the car for 150kms since 3 days and I found that XHP is pretty good, the gearbox seems to better anticipate and understand the driver's desires. multiple Dowshift feels quicker, upshift feels quicker in sport mode and I found XHP pairs very well with MHD V9, gear change are really smooth when they can feel harsh with oem DCT tune especially on V10 map in sport mode.


I think that, like for MHD, custom tune will always be better than OTS but i like the way to choose my maps when I want.


I don't trackday my Z4, for street drive, i think that I can now say that i reach a good ride experience with MHD and XHP OTS maps.

It could always be better, but now I'm happy.

 

[carabuser]

I was actually speaking about XHP returns for DCT cars.

Maybee I'm wrong but I remember that carabuser was disapointed for example, somebody said that shifts aren't really quicker, that gear changes rpm wasn't optimum, that quick downshift when stoping quickly at a STOP was not ok etc....but maybe it was on older XHP revision, they keep updating so problem reported by users should have been resolved.


Personnaly, i drove the car for 150kms since 3 days and I found that XHP is pretty good, the gearbox seems to better anticipate and understand the driver's desires. multiple Dowshift feels quicker, upshift feels quicker in sport mode and I found XHP pairs very well with MHD V9, gear change are really smooth when they can feel harsh with oem DCT tune especially on V10 map in sport mode.


I think that, like for MHD, custom tune will always be better than OTS but i like the way to choose my maps when I want.


I don't trackday my Z4, for street drive, i think that I can now say that i reach a good ride experience with MHD and XHP OTS maps.

It could always be better, but now I'm happy.

xHP is a waste of money on the DCT. It works great on slutshboxes but as you can see in your log it's almost 500ms before timing fully recovers. It should be around 50ms.

But the log does look much better now. No timing dip during spool.

 

[vadonchez]

That's not always so much, it depends on log, sometimes it's better like here:

https://datazap.me/u/vadonchez/v9-1-e50-xhp?log=1&data=5-16-22

I never see timing shift duration below 300ms in my logs.

I don't know the difference between 300ms and 50ms for normal driving condition, is it really noticeable in real world?

Reintroduce timing later isn't a way to avoid postshift timing correction?

Honnestly I found that shifts are pretty quick and if i don't took time to analyse my logs i could never imagine that timing drop oon upshift is too long.

 

[SLOWESTN54]

That's not always so much, it depends on log, sometimes it's better like here:

https://datazap.me/u/vadonchez/v9-1-e50-xhp?log=1&data=5-16-22

I never see timing shift duration below 300ms in my logs.

I don't know the difference between 300ms and 50ms for normal driving condition, is it really noticeable in real world?

Reintroduce timing later isn't a way to avoid postshift timing correction?

Honnestly I found that shifts are pretty quick and if i don't took time to analyse my logs i could never imagine that timing drop oon upshift is too long.

BTW @carabuser does Custom tunes, mans a legend on the key board no exaggeration, Also does custom trans tunes for your dct

 

[carabuser]

That's not always so much, it depends on log, sometimes it's better like here:

https://datazap.me/u/vadonchez/v9-1-e50-xhp?log=1&data=5-16-22

I never see timing shift duration below 300ms in my logs.

I don't know the difference between 300ms and 50ms for normal driving condition, is it really noticeable in real world?

Reintroduce timing later isn't a way to avoid postshift timing correction?

Honnestly I found that shifts are pretty quick and if i don't took time to analyse my logs i could never imagine that timing drop oon upshift is too long.

Well the whole point of the DCT is that it can shift quickly without any interruption to acceleration. Any standard slushbox can shift in 300ms. It might not be a big deal, but you've paid xHP €400 for essentially just a more jerky version of the stock tune.

The rate of recovery after the shift has nothing to do with timing corrections, typically I don't see any post shift corrections on DCT cars. Certainly no increase in corrections as a result of the faster shifts.

 

[vadonchez]

Thanks for reply.
I always had postshift timing correction on my car even on STAGE 0 ....I don't know why and how to solve that.
I imagine that it's fault knock related,I have a friend who has a Z4 35IS too and even if his timing shift duration are >300ms too he has far less postshift timing correction than me.

Even on stage0 my timing cut duration during shift are around 300ms too as shown in this log:

https://datazap.me/u/vadonchez/stage-0-text-10°c?log=1&data=7-23-27&zoom=119-209&mark=107

My point of vue is that if even on stage0 map timing cut duration is the same than with XHP, i can't conclude that XHP makes the situation worse. (I agree that it makes not the situation better too )

I don't feel my car jerky at all with XHP, I have to say that my car feels good, fast shifts, smooth.

Can we say that shift duration time is equal to timing cut duration time?
To me shift could take for example only 90ms but timing cut during shift can last more time like 300ms no?

I agree that timing cut give a power cut sensation during shift but is it really the gearbox shift duration?

If answer is yes, how succed you to understand that gear shift time= timing cut time?

Thanks to share your knowledge with us @carabuser

 

[carabuser]

Thanks for reply.
I always had postshift timing correction on my car even on STAGE 0 ....I don't know why and how to solve that.
I imagine that it's fault knock related,I have a friend who has a Z4 35IS too and even if his timing shift duration are >300ms too he has far less postshift timing correction than me.

Even on stage0 my timing cut duration during shift are around 300ms too as shown in this log:

https://datazap.me/u/vadonchez/stage-0-text-10°c?log=1&data=7-23-27&zoom=119-209&mark=107

My point of vue is that if even on stage0 map timing cut duration is the same than with XHP, i can't conclude that XHP makes the situation worse. (I agree that it makes not the situation better too )

I don't feel my car jerky at all with XHP, I have to say that my car feels good, fast shifts, smooth.

Can we say that shift duration time is equal to timing cut duration time?
To me shift could take for example only 90ms but timing cut during shift can last more time like 300ms no?

I agree that timing cut give a power cut sensation during shift but is it really the gearbox shift duration?

If answer is yes, how succed you to understand that gear shift time= timing cut time?

Thanks to share your knowledge with us @carabuser

It's possible to monitor the transmission operation in the DME as it transmits some information over CAN. Whenever the timing is low like that during a shift it coincides with a request from the transmission to reduce torque to help it complete the shift. Typically that means the full clamping pressure on the clutches is not applied and they will have some slip.

Elongated torque limiters during a shift are normal in scenarios where the TCU hasn't met it's target RPM to engage the next gear, so rather than just clamp the clutches instantly, creating a jerk, it will slowly close the clutches and force the engine to decrease timing or increase/decrease the throttle opening. It's not something that should happen at high load.

A good shift at WOT shouldn't create any jerk or power drop. MHD logging runs at around 100ms intervals so on most of my logs I don't even see the timing reduction trigger or the torque limiter activate:

I did try and work this out with xHP but their response was that I should ignore log data and focus on how it feels. Not exactly the scientific approach. That's why I made my own app to flash my DCT as they lock their flasher down to using the non-GTS firmware.

 

[carabuser]

An example of what my logs with xHP Stage3 looked like:

Both fast and slow torque limiters active during the shift with the fast limiter staying on for 300ms~. You can see the engine RPM actually hangs a bit during the shift compared to the GTS software shown above where it instantly settles and starts climbing again.

I made a program to log the DME at 16Hz~ so should be able to get some better logs when I get time.