Mk4 1.8t air leak

[Legendary123]

Hello I done a 2.0 to 1.8t conversion on my golf all went well apart from it runs lumpy with maf plugged in, I have been roundscrap yards trying others maf units but still dies when revs drop. Runs smoother without maf plugged in, someone says that could mean it's been remapped? I tried blocking the air intake off to see if the engine would stall itself but it didn't so I'm guessing there's a leak somewhere, is there anywhere common to check?

[MoMartin]

it could be a throttle body problem. Clean it up, then clear your engine of any fault codes using vag com.
Are you sure that you blocked off the air intake? Because it would have to be one hell of an air leak to keep it running when you've got it blocked off.
I would have a look for any hoses that might have been knocked off during installation, but as I said, I would give the throttle body clean a go because it won't do it any harm for one, and that solved my rough idling and stalling in one hit.

[Legendary123]

I cleaned throttle body out, wasn't too bad but bit oily, inside the pipe just after the maf unit it's oily too, where the recirculation valve feeds back into the intake pipe it's oily there too

[Dalo Harkin]

all of your pipes will be oily, from the turbo right down into the Intercooler.

have you checked the pancake pipe? its behind the drivers side wheel basically and they are reknowned for leaking at the engine side