NefMoto

Hi to all,

I'm working on a Audi S3 2.0 TFSI 199kw CDLF, that is facing a big issue with misfire.

This issue will interrupt the Lambda closed loop and the misfire counter is reaching abnormal values at idle, partial throttle and WOT.
The only good thing observed is during the first 60sec after Engine starts.
In that moment, Lambda control is working and meantime misfire counter remain at 0. Once lambda control stops to work, misfire counter starts to increase back again.

We have check mechanically speaking everything (leaks, EVAP and all around Kat and Lambda probes) and all is perfect.

Someone has got some issue like this or has some feedback?

According also the MED9.1 Function manual, I believe that bit CWAEVAMZET cab disable the misfire recognition. Could be nice if someone has more infos to share about it.


Thanks for your cooperation.

In the absence of any ori or modified files to check...

Have you tried flashing ori and see if the issue on idle persists?

Check fuel trims in block 32
It is leak related most of the time.

Pressure Test from intake with 0,5bar maximum and see if it holds boost.

File ori in attachment. Thank you!

To be fair, the ori is irrelevant. Anyone here capable of diagnosing the issue will have the ORI. Knowing the changes made to the software is key to understanding if it's a calibration fault.

Flash that ORI back in and see if the issue disappears. If it does, there's your answer.

I've tried to flash the ori file again, check the ori file read from the ecu with an ori taken from Alietech data bank and there aren't any differences. So means file is ok.
I've tried to swap with another Med9 same issue.

The only thing that I've forgot to say is the PCV test that has been done. At the beginning once the oil splint was removed the rpm starts to increased (at idle). So means some air was sucked by PCV system.
We have checked and change everything and now even with PCV system sealed sometimes (specially at cold) the rpm are dropping, but when engine is warm and hot, rpm are still raising once the oil splint is removed.

Hi , have you replace coils ?

I usually got that behaviour from coils or from high mileage injectors

Hi Teo,

coils has been changed with new red one.
I've discovered just now that the spark plugs installed where another type.

Originals normally has 5kohm resistance and the sparks plug founded has 1kohm resistance.


This can affect something on the electronics components ECU included?

Thanks

sparks can not affect something at electronics part . But it can definatelly make car misfiring

Agree. I had to change injectors as one of them caused missfires. This is a common issue on DI injectors with high mileage.

Injectors changed... same issue  :'(

I'm going now to disable CDMA, CDFO and CDMD to see whats up.

Starts to be a night mare...  :'(

Any logs of injection time and rail pressure?

have you make compression test to the car ?If injectors , plugs , coils are checked is the next think in my opinion

Yeah, I believe this is the last thing to do.

I'll do it and I'll report.

Thanks Teo!

Some updates:

- Leak down test (ok)
- Compression (ok)
- Injectors (ok and new)
- Ignition coils (new R8 original Bosch)
- Spark plugs (new BKR7EIX)
- EVAP system (no leak all hoses replaced)
- Flywheel (visual inspection, perfect)
- Fuel system (HPFP and LPFP working and follow the specific pressure)

Car has still Misfires when Lambda control is disabled. Once Lambda control is enabled and it starts to trim, no misfires.

There is something that stop lambda control. But too many functions  :'(

We can close the post...

I've disabled missfire monitoring and that's it.

Thanks to all

If you've got a misfire, then there's something causing abnormal / failed combustion. You need to source that issue and fix it.

Ignoring an illness does not make the body well.

O2 sensor ?

Are the manifold flaps working?

Disable CWBBKH (cat heating after cold start) too, no one needs it...