[335_DE90]

Hi all,

I've got a stock 2010 335D with 128k on it that keep overboosting while cruising on the highway.

The car runs fine around town and during wot pulls but if on the highway doing 60-80mph and you go up a small incline the car goes into limp mode for a couple seconds then return back to normal.

I have replaced all of the vacuum lines and checked the pressure converters and they are fine. I have also replaced the map sensor b/c the car was acting a little hesitant down low and that seemed to alleviate that problem.

Any suggestion are appreciated.

[Asonchadwick]

Any idea the psi at cruise?

[CRJ68]

Well I'm just learning how all this works (I have opposite issue, underboost at higher RPM)

You sure the wastegate is operating?

[335_DE90]

Usually targets 5-10psi

Wastegate is functioning since it holds 27psi steady at wot.

Below is a link to the log I took, Highlighted in yellow is when it actually went into limp mode.

https://docs.google.com/spreadsheets...it?usp=sharing

[335_DE90]

Bump

[badylarz91]

Is it original software or have something made like Stage 1 ?

Please also check EGR Valve, it seems that is closed all the time (or it's offed in software) and that could also make that limp mode.

Regards

[335_DE90]

How would the EGR cause an overboost condition?

It only goes into limp mode under minimal throttle input. Functions normal if driving like an a-hole.

How can you tell the EGR isn't functioning? I didn't log egr percentage.

I am not the original owner of the car, as far as I know it has the stock tune on the car.

[badylarz91]

Originally Posted by 335_DE90

How would the EGR cause an overboost condition?

It only goes into limp mode under minimal throttle input. Functions normal if driving like an a-hole.

How can you tell the EGR isn't functioning? I didn't log egr percentage.

I am not the original owner of the car, as far as I know it has the stock tune on the car.

If EGR is closed all the time, all the exhaust gases goes by HP Turbo, that could make overboost condition becuase of to much exhaust pressure (if EGR would open, some % of gases goes to the engine, pressure in exhaust manifold is lower and then HP Turbo slows down, got it ?).

EGR is controlled to some injection quantity, on WOT its always closed, all clear ?

So log how EGR is operating and we You will see whats going on.

Next possibility is to check the lenght of the rod on the Flap between HP and LP Turbos. Someone could shorten it, and thats why the flap is a little bit to much closed... it could also make overboost when cruise.

As You see there are few options, but You need to make it step by step.

Firstly check EGR and Air Flow (requested and measured - that would give You the answer how EGR is really operating, if all good - it must be almost 1:1 each other).

Regards