Audi S3 coolant "boiling", misfires, coolant in oil

[bodzik155]

Hello guys,
Audi S3 2015 CJX, 90k kilometers mileage.
I'm running out of ideas.
It started with water pump leak - replaced.
While bleeding coolant system after replacing water pump thermostat housing we noticed there is problem with bleeding and water is "bubbling" (video).
My mechanic said it's normal behaviour, because of pressures etc. I didn't quite believe in that, because there isn't any "boiling" in my father's A3 2.0 tfsi and even my friend's same S3.
I was trying to make test for CO2 in coolant, but it was impossible due coolant reaching too fast to the tester.
Engine was sometimes running a bit I did basic diagnosis in VCDS - it showed misfires on all 4 cylinders. Few misfires after 10 min on idle and about 10-20 misfires on each cylinder after hard 1 km ride. Also there was something which looked like coolant under oil cap (picture) - mechanic said it's not coolant (then WTF is this)
Head was reassembled - no signs of wear or anything on gasket and cylinders. Head was checked under pressure with hot water for cracks, then planned and assembled. Coolant system was checked under air pressure. Head and block are straight. Compression is fine.
Result after head regeneration - same problem with boling coolant, no misfires on idle, no coolant in oil.
At least that's what mechanic said. There wasn't test drive yet, because car was on summer tyres. I am picking it up tommorow and will check by myself on road if there really aren't misfires and no coolant in oil.

Car has no problem with power, no white cloud from exhaust. Oil coolant radiator wasn't checked yet, because he said that if it was damaged then oil would be in coolant, because of much higher pressure of oil. Bottom of the engine block wasn't checked too.

I'd appreciate any ideas why is this happening & what else could be checked.
Video

 

[B5NUT]

The system needs to be pressurised, otherwise once up to temperature it's going to boil over. If the tester you have is not working well then try a different tester. You should also be able to bleed the system before the car is fully up to temperature, there is usually a couple of bleed points in the coolant system one being one of the hoses going to the heater matrix.

I don't think you have any problem with the car make sure the coolant is at the correct level and take the car for a run if it's all normal and level is similar to where it started before the run and the hoses are not rock solid then you have nothing to worry about in respect to the coolant. So then it's finding the fault of the misfire

 

[Damo S]

"Few misfires after 10 min on idle"

This is normal I think

" and about 10-20 misfires after 1k blast"

yeah, not great but its not terrible either. The fact its on all cylinders rather than just one counts out a lot of the usual suspects (plugs, coilpacks. injectors). It would be good to test whether just careful normal driving triggers the misfires or whether the car has to be under load / full chat.

Regarding the test. I didnt think the engine had to be running to test the coolant. Its just looking for the presence of hydrocarbons in the coolant. They dont just disappear when the engine stops. Might be wrong.

Sorry to hear about your problems though. There is little more depressing than when your motor is playing up and in potentially expensive ways

 

[AudiRace]

If there was white smoke you blown your turbo... and you posibly fried engine too
if your car is producing a thick, white smoke – you may have a problem. Many times, this thick smoke is due to the likes of a blown head gasket, damaged cylinder, or a cracked engine block, which is causing coolant to burn

 

[Garrett 69]

Oil coolant radiator wasn't checked yet, because he said that if it was damaged then oil would be in coolant, because of much higher pressure of oil.

Get a new mechanic, this one is a clueless monkey.

 

[bodzik155]

Car is probably after chiptuning. I've discovered turbo is pumping almost 1.6 bar (23 psi) in peak. I'm going to restore ECU to stock tommorow. Also EPC error with turned off 4th cylinder (too high pressure) showed up. Probably due too many misfires or knocking. Additionaly error about blocked auxiliary water pump showed up yesterday, but it may be related with me changing HVAC hot country settings from cold country to normal.

 

[bodzik155]

After installing new ecu software misfires are gone. Engine is still lil bit shaking for every several seconds though. I don't know what to check about this shaking if there aren't any misfires.. We've discovered that ignition timing angle is up to -5* on every cylinder from 5 to 6k rpm. Is it normal for these engines?

 

[george forbes]

After installing new ecu software misfires are gone. Engine is still lil bit shaking for every several seconds though. I don't know what to check about this shaking if there aren't any misfires.. We've discovered that ignition timing angle is up to -5* on every cylinder from 5 to 6k rpm. Is it normal for these engines?

pretty sure it's plus or minus 5 max but have heard of issues at 4.5 up