Anyone had the "shift bog" on a stock or tuned 1M ?

[cstavaru]

Hello,

Not sure if you are aware of this "shift bog" occurring on manual transmission N54 cars. It's like after a shift (usually 3-4 shift), the boost builds very slowly and the car loses power for like 1 second before the boost begins building again.

It does not occur everytime, however.

It seems to be a transmission protection of some sort, the ECU orders the target boost to rise slowly instead of rapidly after certain gear shifts. So it's not boost lag, it's what the ECU really wants.

My question is, has anyone with an 1M ever felt this when shifting fast between 3rd and 4th ?

[Dackelone]

Maybe you are getting detonation in the higher gears. Most cars will build more sustained boost in higher gears. What kind of fuels do you use?


Or maybe you have a boost leak or BOV problem. I would take a good look at your charge pipe. Maybe even remove it and check it for cracks. Also... the vacuum lines going to the wastegates have been known to blow off at the turbo(s).

Dack

[cstavaru]

Originally Posted by Dackelone

Maybe you are getting detonation in the higher gears. Most cars will build more sustained boost in higher gears. What kind of fuels do you use?


Or maybe you have a boost leak or BOV problem. I would take a good look at your charge pipe. Maybe even remove it and check it for cracks. Also... the vacuum lines going to the wastegates have been known to blow off at the turbo(s).

Dack

No, it's not this, here is the graph (magnified at the shift event) and you can see how the ECU orders the boost (boost target) to rise slowly with a pre-defined slope. It's like it tries to protect the drivetrain. This only happens in certain cases, however.

GIAC said that it is a transmission protection (very plausible) but the question is, does the 1M have it or not ?

[OrangeCrush]

What RPM are you shifting fast between 3rd and 4th? I havent noticed it but I will test it out after work.

[cstavaru]

Originally Posted by OrangeCrush

What RPM are you shifting fast between 3rd and 4th? I havent noticed it but I will test it out after work.

About 6300-6500. The higher the RPM the more likely the bog. But you have to shift reasonably fast.

[Fundahl]

It's a boost targeting issue with the DME. I've tuned most of it out with the JB4, but the faster you shift the more likely it is to happen.

I say ditch all this vacuum canister shit for a single GTX3076 and run a conventional waste-gate!

[cstavaru]

Originally Posted by Fundahl

It's a boost targeting issue with the DME.

From that log it seems to be very deliberate action from the ECU. Look at how straight the boost target slope is. It's definitely a piece of code inside the DME that does this.

This evening I did some tests and tried to shift very abruptly (but not overly harsh). No bog...but I can see how the next time I'm going to the track the car will return to its habit.

[piele_bps]

Any 1M driver here ??

Any 1M owner could chime in and let us know if the 1M bogs on high rpm fast shifts ?

[dossantr]

Originally Posted by piele_bps

Any 1M driver here ??

Any 1M owner could chime in and let us know if the 1M bogs on high rpm fast shifts ?

Yep mine started to bog only from 3rd to 4th at around 6000rpm. My milage at that time was around 2 500km. Took my car to a BMW dealer and complained about it. They did a software uprade and the problem was solved. Old software intergration level was E89X-11-03-510 and the new software intergration level is now E89X-11-09-505.

[MrRoboto]

Havent noticed anything but I will pay more attention to it next time at the track. ~6300rpm in 3rd is ~180km/h. Not many chances to experiment.

[piele_bps]

^ We tried this software updates, and nothing, the n54 335i still bogs on high rpm fast shifts..

Maybe the 1M doesn't have this protection in ECU, because it is an M. But if you say that it bogged... Maybe you can try to fast shift 3-4 at 6500 - 6700 rpm. I am sure that it will bog again.

Let's see what others 1M owners have to say about this.

[ozinaldo]

Originally Posted by piele_bps

^ We tried this software updates, and nothing, the n54 335i still bogs on high rpm fast shifts..

Maybe the 1M doesn't have this protection in ECU, because it is an M. But if you say that it bogged... Maybe you can try to fast shift 3-4 at 6500 - 6700 rpm. I am sure that it will bog again.

Let's see what others 1M owners have to say about this.

I have shifted a few times from 3 to 4 and over 6500 rpm, never noticed anything unusual...yet.

By the way, to Mr. Roboto, if I remember correctly a stock 1M in 3rd can only reach to 181 km/h at 7000 rpm not at 6300, so either your car is with a strong tune or the speedo is showing way much more than real because my experience is also in paralel with stock numbers, I shifted many times around an indicated 180 (which means the car was doing in reality around 170 -175) and it was 6700-6800 rpm.

[rapter]

Bumping this old thread.
My friend 1m started to bog when shifting hard

Is there a solution or cause?

[twinturbovan]

Originally Posted by rapter

Bumping this old thread.
My friend 1m started to bog when shifting hard

Is there a solution or cause?

MHD has a shift bog fix now. I'm not sure if theres a difference of the 135i and 1M but I just installed Pure Stage 2 Pure High Flow Turbos and I wasnt able to build boost with anti-lag because of shift bog issues. Once I selected the shift bog fix on MHD it fixed all my bogging issues.