BAG Engine Underpowered - Stuttering / Dithering / Misfire - What to log on VCDS?

[willdudeuk]

Is there any particular spots I should pay attention too regarding leaks?

is it best with the engine cover off?

at idle? Or revving at a particular range?

[willdudeuk]

Can you also advise about resetting learned values in engine module > adaptations........

Is this the same as doing a battery disconnect for an hour? or touching the terminals together to completely discharge?

Or completing an autoscan and clearing codes? (Hear this resets fuel trims?)

It comes up with a pop up that says something along the lines:

WARNING
Resetting adaptations in this module is likely not reversible,
and reparametrization may require
the dealer tool with an online connection.


Are you SURE you want to proceed.

2020-04-26_221326.jpg.c295e74d98778b7e4f5fba769c971b0d.jpg

[Crasher]

Yes, that's the one. The crankcase of the engine must be air tight or the breather system will draw in air, to test the system you pressure test with a smoke machine from the throttle body and look for leaks.

[willdudeuk]

Could I therefore potentially have a leak on the oil sump? if this hasn’t been sealed correctly? Would that cause the rough running?

[Crasher]

Yes, or the chain cover but you would expect an oil leak if that were the case.

[willdudeuk]

It’s all looking pretty dry under there with no obvious leaks.

Will have to get it smoke tested but I don’t have one myself. Shall have to get it booked in somewhere that has one.


So the whole or the crankcase has to be sealed otherwise you’ll get an air leak and therefore lean running?


can lean running be identified with fuel trims in vcds? There are long and short fuel trims from what I’ve seen.

[Crasher]

Yes the crankcase as a whole must be air tight, the air in is provided by a breather line and the crankcase fumes vented out of the breather into the inlet manifold. There is a display for lambda correction, this needs to be less than ten percent, it should be labelled in advanced measuring blocks. In Basic Settings 099 you can also turn the Lambda control off but that is only useful if you have a pre cat sampling port and a five gas analyser.

[willdudeuk]

Lambda correction shows as 1.16

Lambda Correction.jpg

[willdudeuk]

Update .....after looking at misfire counter MVB 014, 015, 016

I am getting misfire on cylinder 1 (ocassionally) but mainly cylinder 2....

Just doing the test in netural on the driveway but the misfire recognition keeps going from enabled to disabled....

Do I need to go on a drive to check and log this?

Also it seems to clear the counter to zero when I lift foot off throttle?


But looks like Ive got a misfire on cyl 1 and cyl 2....


Should I be swapping round coils and new plugs? Or just replace the lot?

Compression check would be a good idea too....

Please advise as to what to do next.

Thanks

014 015 016 MVB.JPG

[willdudeuk]

Also keep reading about a bad earth under the passenger headlight that can impact the coils?

Is there a picture of this somewhere so I can confirm if it’s a bad earth / broken / severed cable?