[RSL]

Originally Posted by Hoper

Ahh yes forgot to mention road was wet so couldn't just floor it, will do another log on dry roads in the next few days

and yep I'm at around 650m or 2100ft so altitude could be playing a part

why would load exceed request? what generally causes that to happen?

Thanks very much for your help, really appreciated

Whoops just checked, the throttle closure is me changing gears, 3rd to 4th sorry should mention its a manual and yep I can see the load actual fluctuating up and down above and below the load request at light throttle, that'd be why its surging so just need to know why its going above the request...

and yep have the linear throttle option on, might turn it off and reset the adaptations, come to think of it I haven't reset them since replacing and coding the injectors and fitting the DPs, should do that...

Tuning and/or environmental factors can cause actual to exceed request. That can absolutely be tuned out. Most OTS maps aren't based on or even thinking about a couple thousand feet above sea level. The OTS maps run request/actual right on top of each other, so there's little margin for any error like that. To be fair, so does the stock map, but custom tunes can dial in headroom.

The throttle closure at 6400rpm is your shift, this throttle closure at 3100rpm is at the beginning of the pull and may be part of the hesitation if it's in that area: http://www.datazap.me/u/hoper/catles...-62&mark=41-44

Torque request is mapped to the pedal, which is how you wind up with a wide open throttle plate/full load request at less than full pedal. Try the stock throttle option (modifies the torque request per pedal position table). Sport mode will also change to a different torque request table, which generally has more torque requested at lighter pedal. I am not sure if the linear/stock pedal options on MHD change both tables or just non-Sport.

[Hoper]

Originally Posted by RSL

Tuning and/or environmental factors can cause actual to exceed request. That can absolutely be tuned out. Most OTS maps aren't based on or even thinking about a couple thousand feet above sea level. The OTS maps run request/actual right on top of each other, so there's little margin for any error like that. To be fair, so does the stock map, but custom tunes can dial in headroom.

The throttle closure at 6400rpm is your shift, this throttle closure at 3100rpm is at the beginning of the pull and may be part of the hesitation if it's in that area: http://www.datazap.me/u/hoper/catles...-62&mark=41-44

Torque request is mapped to the pedal, which is how you wind up with a wide open throttle plate/full load request at less than full pedal. Try the stock throttle option (modifies the torque request per pedal position table). Sport mode will also change to a different torque request table, which generally has more torque requested at lighter pedal. I am not sure if the linear/stock pedal options on MHD change both tables or just non-Sport.

Thanks very much for that, will try the sport mode option and the stock throttle mapping options individually and together and see what I get in terms of results

[bartbes]

I am at sea level and switched from linear throttle back to stock throttle. No luck. No boost leak, i'm at 21 psi at 6k rpm with 48%wgdc. Going to check on plugs and injectors again and if all looks good i'll swap the hpfp again

[FIFTW]

Suck to hear others are having this issue. I was as well until I recently switched to NGK 59770 plugs..it seems to have helped almost eliminate the hesitation. Mine was happening at 2900-3100RPM and would get worse as the car warmed up. I haven't changed anything else in my car besides the plugs.

[bartbes]

This is a log of the issue. You can see it until i give it a little more throttle and its gone

http://www.datazap.me/u/bartbes/fluc...og=0&data=3-21

[Sgop335]

Originally Posted by bartbes

This is a log of the issue. You can see it until i give it a little more throttle and its gone

http://www.datazap.me/u/bartbes/fluc...og=0&data=3-21

Great capture, mt or at?

[bartbes]

At

[Hoper]

Originally Posted by bartbes

This is a log of the issue. You can see it until i give it a little more throttle and its gone

http://www.datazap.me/u/bartbes/fluc...og=0&data=3-21

Yep RSL was correct and your log is the same as mine, if you look at the load request and load actual you can see where the engine management is trying to match them but is causing the fluctuation by overshooting...

[RSL]

Originally Posted by Sgop335

Great capture, mt or at?

+1, nice job. The issue occurs at the higher accelerator position/load too, but definitely to a less noticeable extent.

http://www.datazap.me/u/bartbes/fluc...15-17-18-21-25

[bartbes]

What do you guys think of this?



not present



present

These were taken in the same situation, with only a few minutes in between

Edit. In my case it is NOT rpm related. I can make the same present and not present logs on any rpm between 1400 and lets say 3500. How higher rpm goes the faster it oscilates up and down, shorter sinus.

[RSL]

Originally Posted by bartbes

What do you guys think of this?

Attachment 1674320

not present

Attachment 1674321

present

These were taken in the same situation, with only a few minutes in between

Different RPM = different table rows / calcs.

[bartbes]

Originally Posted by RSL

Different RPM = different table rows / calcs.

That doesnt matter.

Lambda 1 and 2 seems odd to me

[NoGuru]

Originally Posted by Jeff@TopGearSolutions

Unfortunately it's such a common issue and a broad one at that.

Most of the stuff you mentioned could in fact still be the culprit.

I've actually replaced all 6 plugs, injectors and coils at the same time and still had the hesitation. Walnut blasting is up next for me but other then that it might just be in the tune. I'm on MHD Stage 2+ myself and I swear it's in the tune. If I go back to stock I can't feel the hesitation. If I reset adaptations the hesitation goes away for a little but eventually comes back. I've also tapped the intake manifold for the Tial and that did help a little. It's actually barely noticeable probably for an average Joe but I can still feel it. I think it just comes down to process of elimination with these kind of problems.

Wow, this is the same for me on MHD Stage 2+ and if I reset adaptations it goes away for a short period of time. Might do a custom tune soon to try and get rid of it.

[Spyro235]

Hey guys, just chiming in as I just found this thread. I have a 2007 335, 6 speed. I'm getting WILD oscillations on the highway at very light throttle, anything over 2950 rpm. If I'm holding a constant speed anything over 80, the car starts bucking like crazy. Oscillating steadily, unable to just keep a constant steady throttle. Also, on startup, sometimes it oscillated and stumbles, and it'll diedown to 3-400 rpm, and shoot back up to 1000ish, and then stumble back down to the 300ish. there have been a few instances where coming to a stop, pushing the clutch in, the car has outright stalled out on me. I've done LOTS to the car to try to alleviate this. Please note, I do have failing turbos. My wastegates rattle, and while the car will build boost, the boost wavers until it springs the code. I would like to solve the stumbling/oscillation before I spring the money for new turbos/tune/intake/DP all at once. Another note- like mentioned before, it I'm going for boost or give the car any kind of real throttle input at all, the oscillations immediately go away, and it runs smooth as can be.
I'll try to list what I've done off the top of my head (all done by Matt at ZNM, he's been a huge help to me.
Index 12 injectors, coded in.
All 6 mosfets replaced, 2 were found to be bad. Might as well do them all while I've got Matt in there.
Checked o2 sensors, and tmap- they all respond wonderfully when being monitored in real time
Searched for boost leaks, found a cracked VC, replaced. No other boost leaks found with smoke test.
New battery installed this weekend, old one crapped out and was giving me issues for months.
We think my Low pressure fuel sensor is bad, Matt is sure it is. Thinks it wont affect what's happening, since he has no reason to believe that the lpfp isnt giving appropriate pressure. it's pegged at around 107psi IIRC, and doesnt change much. I told him today that I'd like to go ahead and replace it anyway, just to get a working sensor in there. In theory, it could be the sensor/ the lpfp crapping out, from the strictly low demand situations my oscillations and stumbling occur at. Idk, just my brain trying to comprehend the money I've thrown at this problem while it undoubtedly persists. And I'm hesitant to work on the 335... my 330 drift car I'll drop the transmission again without hesitation, but the tech in the 335i scares the piss out of me.
Just my 2 cents, let me know if there's anything blatantly I'm missing anything, and my manual car behaving the same means it might not be your tq converters contributing to the issues.

[RSL]

Originally Posted by bartbes

That doesnt matter.

Lambda 1 and 2 seems odd to me

Just because it happens at that RPM at other times, doesn't mean it doesn't matter. Whenever it does occur, does a little more or less pedal make it stop?

Yes, AFRs are messed up when the surging occurs. The double-helix pattern of the AFR in the first log is correct.

The issue is easily correctable via tune.

[bartbes]

More throttle makes it stop, less doesnt until im completely off.
According to nu tuner, it isnt in the tune unfortunatly, but i still hope so it is.

If it is in the tune could jou explain why one moment it occures, the next minute it is gone, then it is there but less pronounced, and the next day it is back again? All in random order btw

[RSL]

Originally Posted by bartbes

More throttle makes it stop, less doesnt until im completely off.
According to nu tuner, it isnt in the tune unfortunatly, but i still hope so it is.

If it is in the tune could jou explain why one moment it occures, the next minute it is gone, then it is there but less pronounced, and the next day it is back again? All in random order btw

Far be it from me to tell your tuner how to tune, but if still using stock request tables or even close, I suggest taking a close look at them and then ask why you’d want to request so much output (especially after tune increases) smack dab in the middle of the cruise RPM/pedal ranges. There are other things that can be done in addition to/instead of, but I'd start there.

Much goes into the DME calculations and almost anything can trigger it here and there if it’s right on the edge, but more likely, it's the simple fact that minute differences in pedal position could mean anything from a 20-70% request in the cruise range on the stock tables.

[Sgop335]

Was going to elaborate some...
The log i saw, showed a 5% increase in pedal w a 20 point incrs in load. I will try to post my pedal tables from tunerpro. But that seems a litl high, since a 20 pt increase could be 10-15%. Guess what happens is when the load tables are increased perhpas the % increases get higher...

[MJ80.]

Checking in with similar sputter/hesitation at only cruise and light constant load. Mhd e40 flash.

New injectors and plugs, i know i have o2 issues, suspect o2s.

[bartbes]

This goes beyond my knowledge sorry guys.

I could flash it back to stock to check if it solves the problem,
cant hurt when i baby the car right? (It has stage 2 turbo's)

[RSL]

Originally Posted by bartbes

This goes beyond my knowledge sorry guys.

I could flash it back to stock to check if it solves the problem,
cant hurt when i baby the car right? (It has stage 2 turbo's)

That stock table is the problem. By flashing back to stock, it may only alleviate it due to the lower output at the same requests. Your tuner should be able to knock that change out in a few minutes. If the map isn't locked, you can DIY.

[bartbes]

Thanks, i wil contact my tuner about this. I'll be sure to post of it can be taken care of