Surging revs and misfires after PCV replacement

[TsiTaxi]

Hi

I have a 2.0TSI EA888. Had been having issues with high idle. Car would tick over around 1200 and not really come down from that. Was also getting P0507 Idle RPM higher than expected. I changed the plugs for Bosch Platinums last week as I was still on the original VW/NGKs after 70k, but kept the coils. Upon testing by removing oil filler cap at idle the revs stayed the same so I thought PCV. Ordered one off eBay and fitted. Now it's even worse - After fitting I started up the engine and it sounded very loud/tappy and sounded as though it was misfiring with a boat-like chug from the exhaust and engine wobbling all over the place. I was worried some crap may have fallen off the nooks on top of old PCV upon removing into the valve cover but had cleaned up what i could.

The idle generally now falls back down to 800ish after initial warm up and the car does seem to drive a bit smoother, but revs are now surging which they weren't before. For example if i pull up to lights and put it in neutral the revs gradually creep up to about 1500ish and more, and take a while to fall back down. Also the effect of engine braking is not what it should be - car decelerates slower in gear now too as it is still giving a bit of gas when foot is off the accelerator. P0507 code is back too. If i remove the oil cap at idle not much happens with the engine which suggests that the air leak is still there somewhere. I didn't replace the PCV to intake manifold plastic hose - should I have? Last night when I started up, the car also felt like it was misfiring again, with a flashing CEL but no extra code other that P0507. Vacuum reading fluctuates a fair bit when I monitor with my OBD tool.

I also have oil seeping down bell housing so suspect blowing out of rear main seal; any ideas of where to look for vacuum leaks next? Or could RMS be a considerable source of leak? And reckon I will be safe to drive 500 odd miles to York and Back this weekend? 

Edit: I do own VCDS but don't have access at the moment - I used torque and OBD reader which now shows pending codes 0300, 0301, 0302, 0303, 0304 namely all cylinders misfiring

[pburgess22]

Im also very interested in what people have to say about this. My 09 scirocco has the same symptoms before and after a pcv change as well as plugs and coils. The garage also found oil at the back of the engine so i was thinking rear main seal has gone.

[pudding]

Hi

I have a 2.0TSI EA888. Had been having issues with high idle. Car would tick over around 1200 and not really come down from that. Was also getting P0507 Idle RPM higher than expected. I changed the plugs for Bosch Platinums last week as I was still on the original VW/NGKs after 70k, but kept the coils. Upon testing by removing oil filler cap at idle the revs stayed the same so I thought PCV. Ordered one off eBay and fitted. Now it's even worse - After fitting I started up the engine and it sounded very loud/tappy and sounded as though it was misfiring with a boat-like chug from the exhaust and engine wobbling all over the place. I was worried some crap may have fallen off the nooks on top of old PCV upon removing into the valve cover but had cleaned up what i could.

The idle generally now falls back down to 800ish after initial warm up and the car does seem to drive a bit smoother, but revs are now surging which they weren't before. For example if i pull up to lights and put it in neutral the revs gradually creep up to about 1500ish and more, and take a while to fall back down. Also the effect of engine braking is not what it should be - car decelerates slower in gear now too as it is still giving a bit of gas when foot is off the accelerator. P0507 code is back too. If i remove the oil cap at idle not much happens with the engine which suggests that the air leak is still there somewhere. I didn't replace the PCV to intake manifold plastic hose - should I have? Last night when I started up, the car also felt like it was misfiring again, with a flashing CEL but no extra code other that P0507. Vacuum reading fluctuates a fair bit when I monitor with my OBD tool.

I also have oil seeping down bell housing so suspect blowing out of rear main seal; any ideas of where to look for vacuum leaks next? Or could RMS be a considerable source of leak? And reckon I will be safe to drive 500 odd miles to York and Back this weekend? 

Edit: I do own VCDS but don't have access at the moment - I used torque and OBD reader which now shows pending codes 0300, 0301, 0302, 0303, 0304 namely all cylinders misfiring

Rear main seals going on the EA888 is common when the PCV goes.  A leak down test will confirm, but oil dripping out of the bell housing is a classic sign.  Did you fit a genuine PCV or a pattern one?