Please help with Mk4 1.4 8v throttle body query.

[djwnomad]

Hi I have just serviced my girlfriend's 97 P reg 1.4 8v polo and have a question. It idles a bit rough (steady rpm but feels a bit shaky). It is also a bit violent on throttle (revs increase rediculously quickly like the flywheel has no thickness?) and can stall when slowing down as the rev's approach idle speed.

Anyway I tested loads of the components like the idle control valve and throttle position sensor and they were within Autodata's normal votage and resistance ranges although the TPS is hard to test correctly so I can't discount it. At the same time I had a look at the butterfly valve in the throttle body and noticed on closed throttle the butterfly was ever so slightly open, probably a couple of degrees? It was not the throttle cable being over-tightened because it stayed like this when I unclipped it. I could push the butterfly closed to 90 degrees but then it popped back open a few degrees. Can anyone tell me if this is normal? I suspect the TPS!!

Thanks from a newbee!
David

[The_phat_controlleruk]

I would suggest cleaning it and having it re-aligned using VAG-COM. Cleaning it will get rid of any gunk that has built up while VAG-COM will correctly position the butterfly. If that doesn't work, then I would suspect the TB.

[djwnomad]

OK thanks, I'll give it a good clean then.