NefMoto

Hi!

I'm running a Seat Leon 1.8T, AUQ engine. Stock internals and original chip.
There's a strange stumbling problem with the car right after starting, or when loaded directly after  a successfull cold start.
All this happens only below ~5deg C.

I've checked vacuum lines, fuel delivery, temp and MAF sensors and still couldn't trace the cause.

I've prepared a log with ME7Logger (thanks to Setzi!) and apparently when the problem occurs the ECU simply doesn't supply enough fuel.
It's over my head why.

Any ideas welcome!

If not stock fuel injectors, did you read the S4 wiki tuning article regarding warm up fueling?

http://s4wiki.com/wiki/Tuning#Idle_LTFT_and_idle_misfires
http://nefariousmotorsports.com/forum/index.php?topic=320.90

Also, try cold start fueling maps

What are your STFTs during warmup?

Thanks for your answer.
Unfortunately the lambda control is not active yet when this problem occurs.  When it comes up the engine is running fine already. At that point it is between +-5%.  The LTFT values have been cleared before making this log.

The injectors are stock, as the whole engine is, the only alteration here is deleted SAI system -but not disabled in the chip yet.

Also worth to mention that the car has an LPG system but this problem only occurs when its running on regular gasoline after start.

If you've deleted the SAI system, the ECU is expecting to very lean lambda from the O2 sensors, since the job of the SAI is to lean out the mixture to warm up the catalyst elements.

The first thing I'd do is code out the SAI system.

This thread is a good read - http://nefariousmotorsports.com/forum/index.php?topic=615.0

CWKONABG should probably be used to code out the SAI system. Killing diagnosis != coding it out.

Thanks, I know I need to disable SAI code.   
Unfortunately this problem was already there before the SAI has been removed.
I have a log where I see lambda=0,75 when SAI is supposed to push air -for cat heating I guess.

Up to now I  haven't found definition files for my 06A906032DE ECU to fiddle with, maybe I'll need to go for another -well defined- base program (from similar AUQ engine)?   

Maybe SAI was not functioning prior to being removed, so functionally wasn't there even before being removed.

Apart from the whining noise it generated it seemed to work OK, there was no DTC related to SAI (before  ;D )