N55 with DCT RPMs fluctiation with AC On Finally Resolved!

[TridenTBoy]

Originally Posted by Ganque

Hey guys, just a quick update. I informed everyone that after going back to the stock intake the car got partially fixed. But on hot outside weather the issue will come back no matter what.

So I finally got it fixed! This time for real and permanently:

After going through all the fixes mentioned at the OP, and of course going back to the OEM air box I decided to use my K+DCAN cable one more time (I was bored and wanted to "chat" with my DME and have a deep conversation on how much I hated my car at this point)...
So I loaded INPA
Selected 1 Series
Selected Gearbox
and I couldn't see my DCT transmission listed... if I select any other transmission (GS19 for example) I was getting an error message saying (No response from GS19 module. Your current module DSG_90)
So I decided to go directly to my INPA.ini editor and include the DSG_90 option manually.
Well.... boilá, I was able to finally get into the DSG (DCT or DKG) transmission menu through INPA!

So I was able to reset all the adaptations including clutches pressure levels, oil adaptation and even temperature adaptations.

Then I want back to the Engine menu and reset 2 things:
- Reset Throttle Adaptations
- Reset Air Pressure Adaptations

And then... BOOM!! Problem solved! No more throttle lag, no more RPMS fluctuation... no more issue.

SO here is my theory:
The Throttle Body was acting with a software based delay, so the transmission working with the tb was not coordinating in the correct time. Long story short: The thorttle body was opening later and closing later, generating a false vaccum and causing the stall on the car.


SO AS A FINAL CLOSURE, and I HOPE THIS HELPS TO ANYONE HAVING THE INFAMOUS DCT (DKG) PROBLEM RELATED TO THROTTLE RESPONSE AND RPMS FLUCTUATION AND STALL WITH AC ON:

Do this in this order:

- Make sure that you are not having boost or vaccum leaks.
- Took the car to the dealer for a software update (Mentioned the SIB 12 15 14)
- Use INPA to reset transmission and throttle adaptations (the dealership won't do this for you).

This is a SOFTWARE related issue.

Christ... This needs to be something we can easily do with an app.

[Ganque]

Tagging some of the OGs around just for awareness.
MHD Tuning WedgePerformance @Terry@Burger

[UR25IO]

JUST GET MHD AND PROBLEM SOLVE!

Over the last 5years with various tunes MY 2011 135i N55 dct had been doing it, after jumping onto MDH a few months ago- issue GONE!!

[Xer0449]

Originally Posted by UR25IO

JUST GET MHD AND PROBLEM SOLVE!

Over the last 5years with various tunes MY 2011 135i N55 dct had been doing it, after jumping onto MDH a few months ago- issue GONE!!

Not an option (yet) for some of us.

[Ganque]

Originally Posted by Xer0449

Not an option (yet) for some of us.

Exactly! Mine is also a 2013 which has the MEVD126 DME, MHD is not available for us yet... So yeah, that's the current solution, even for thos who doesn't want to install a tune to fix this.

[Xer0449]

Originally Posted by Ganque

Exactly! Mine is also a 2013 which has the MEVD126 DME, MHD is not available for us yet... So yeah, that's the current solution, even for thos who doesn't want to install a tune to fix this.

I got my bimmerfreaks cable in the mail. Cars on the lift getting some goodies in, but I'll let you know how reseting the adaptions goes.

[juld0zer]

Thanks OP for testing and demonstrating INPA works with the DCT! I personally would strongly advise against using the Tool32 method. Yes it resets the parameters but it doesnt recalibrate like ISTA/D does.

[mjack]

Just wanted to update this thread and let everyone know that I had this exact same problem and solved it 100% simply by taking out my MAF sensor and spraying it down with CRC MAF Cleaner.

I had a feeling it may be the MAF after I forgot to plug it back in after I installed my DP . When I had the MAF completely unplugged, my DCT was nearly completely stalling and was brought back to "normal" when I realized it was unplugged and plugged it back in.

Even though the MAF looked spotless, after I sprayed it down, my RPM fluctuations and even the throttle delay while the AC is on has completely disappeared.

Cheers!

[Xer0449]

Not only does mine fluctuate, but sometimes it tries to save itself from stalling and revs up as I crawl to a stop in traffic...in gear - lurching the car forward.

[zx10guy]

See my thread here:

http://www.1addicts.com/forums/showthread.php?t=1386273

I too had the lurching problem. It got really bad it was consistently repeatable with the A/C turned on. And it made the car practically undriveable in stop and go traffic.

I did the usual suggestions. PPK and SIB 12-15-14 (if I recall the SIB correctly). and for good measure the Dinan S2 tune. The S2 tune seemed to fix the throttle response issues with the A/C off. But didn't help the situation with the A/C on. The link I provided above outlined the BMW tech's notes on what he did. So far I'm over a month out and the car drives pretty much perfectly now.

[mjack]

Originally Posted by Xer0449

Not only does mine fluctuate, but sometimes it tries to save itself from stalling and revs up as I crawl to a stop in traffic...in gear - lurching the car forward.

Mine would do the same thing and I also live in LA so I understand the risk associated with the symptom. I know it sounds silly but I highly suggest trying what I did with the MAF just to see what happens.

I've been lag/lurch/ac rpm fluctuation free for 3 days now.

[Xer0449]

Another N55 DCT in LA? We're gonna have to cruise!

I'll give it a shot, thanks!

[OTN55]

Originally Posted by UR25IO

JUST GET MHD AND PROBLEM SOLVE!

Over the last 5years with various tunes MY 2011 135i N55 dct had been doing it, after jumping onto MDH a few months ago- issue GONE!!

same with me

[PDXE82]

Originally Posted by jack135is

Just wanted to update this thread and let everyone know that I had this exact same problem and solved it 100% simply by taking out my MAF sensor and spraying it down with CRC MAF Cleaner.

I had a feeling it may be the MAF after I forgot to plug it back in after I installed my DP . When I had the MAF completely unplugged, my DCT was nearly completely stalling and was brought back to "normal" when I realized it was unplugged and plugged it back in.

Even though the MAF looked spotless, after I sprayed it down, my RPM fluctuations and even the throttle delay while the AC is on has completely disappeared.

Cheers!

This is interesting and simple if it sticks. I'm wondering if you had the battery disconnected during the MAF cleaning and it just reset the adaptations? Please give us an update after a few more driving cycles to see if the problem is resolved. It's such a mystery of which fix works on different vehicles.

[mjack]

Originally Posted by PDXE82

This is interesting and simple if it sticks. I'm wondering if you had the battery disconnected during the MAF cleaning and it just reset the adaptations? Please give us an update after a few more driving cycles to see if the problem is resolved. It's such a mystery of which fix works on different vehicles.

I was very surprised at how it fixed the issues entirely. I had my battery connected too so nothing was reset.

Just drove the car again today for over an hour and 50+ miles with some heavy traffic while it was 85*+ outside. Had the AC on, no fluctuations/delays/etc. My cars issue was definitely the MAF apparently.

[c1pher]

This may seem silly, but how do you clean the MAF? I always worry about somehow messing it up.

[mjack]

Originally Posted by MGM135is

This may seem silly, but how do you clean the MAF? I always worry about somehow messing it up.

I found and followed this DIY guide - http://www.e90post.com/forums/showth...46#post8937746

It's pretty straight forward, just be careful with the sensor. Make sure the car is completely cooled down.

[juld0zer]

Originally Posted by PDXE82

This is interesting and simple if it sticks. I'm wondering if you had the battery disconnected during the MAF cleaning and it just reset the adaptations? Please give us an update after a few more driving cycles to see if the problem is resolved. It's such a mystery of which fix works on different vehicles.

Driving with the MAF sensor disconnected usually logs a fault. Reconnecting it can reset adaptations on some makes of vehicles. Do some more driving and report back after a month

[mjack]

Originally Posted by juld0zer

Driving with the MAF sensor disconnected usually logs a fault. Reconnecting it can reset adaptations on some makes of vehicles. Do some more driving and report back after a month

I had already disconnected it previously when installing my JB4, and another time while changing spark plugs and I still had the issue after both times. I think its safe to say that the adaptations that need reset to potentially fix this issue have to be done with INPA. But first, try cleaning your MAF.

[DHsing99]

is this still the best/only way to fix the lurching with ac on? tried cleaning the MAF and the car ran better but didn't solve the problem

[Joe@TopGearSolutions]

Originally Posted by DHsing99

is this still the best/only way to fix the lurching with ac on? tried cleaning the MAF and the car ran better but didn't solve the problem

Your DME needs an update. There were two updates that corrects that problem.

[Ganque]

Originally Posted by Joe@TopGearSolutions

Your DME needs an update. There were two updates that corrects that problem.

I updated my car twice at the dealership and this did not fix the issue.
My suggestion is to ask the dealership to Reset the Intake, Throttle and Gearbox adaptations during the update period.