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2.0 TSI fuel in oil/rough idle issues help please

Posted: Sun Nov 05, 2023 4:08 pm
by Monzoa
Wondering if anyone can help diagnose what’s wrong with my car before I put it to the garage.. any suggestions appreciated.

Car is a 2009 scirocco 2.0 tsi caw engine.

Bought it a few weeks ago with misfire codes on all cylinders, car idled rough and when revving slightly in neutral revs would take ages to fall back down.

Changed pcv, cleared codes and thought all problems were fixed. No misfire codes on vcds, revs were fine again etc but idle did still seem to be a little rough/felt like it was missing slightly but no codes or misfires logged on vcds.

Drove fine like this for a few days then mpg dropped from 32 to 22 with a smell of fuel coming from oil cap and dipstick and also noticeable in cabin at idle. This was also very soon after I hit a big pothole on front n/s wheel but don’t see how this could be related.

Changed plugs as they needed done anyway and they seemed to have oil/maybe fuel on the threads? Have photos if they are any use.

Just did compression test and 192 psi across all 4 cylinders (dry test with engine warm).

Was thinking injectors, car is on 120k and haven’t been done that I know of but wondering if anyone can suggest other checks I can do or if there’s a way of testing faulty injectors without pulling them out?

Car also puts out some white smoke at idle. Does it when outside temp is warmish so don’t think it’s condensation, increases when revved but no smoke when driving.

I have vcds but not great with it tbh, happy to learn though.

Checked fuel rail pressure and then switched engine off and it rose 20 bar or so which I believe means hpfp/fuel system isn’t leaking?

If anyone can help would be much appreciated, I have a week off work so hoping to try get it sorted before then. Cheers.

Re: 2.0 TSI fuel in oil/rough idle issues help please

Posted: Wed Nov 08, 2023 6:15 pm
by bigkris06
White smoke and fuel in oil would lead me to point in the direction of head gasket, but your compression test would suggest otherwise.
Have you done an oil and filter change? As a misfire could also leave un burnt fuel in the cylinders which may seep past the piston rings which may explain the smell of fuel in oil.
Petrol injectors aren’t a big deal to take out but I’d assume you’d get a code for that if it were the issue.
May be worth revisiting the pcv to make sure all surfaces are sealed properly and tight.
May also now it’s been a couple days may also be worth checking codes again.
Sorry it’s not much info but hope it helps 😊

Re: 2.0 TSI fuel in oil/rough idle issues help please

Posted: Wed Nov 08, 2023 8:04 pm
by Roy_01
Other possibility could be high pressure fuel pump leaking fuel into your engine block oil.