rough idle

[keithcdb]

I own a mk3 golf gti 2.0 16v (93)
It starts ok and revs well, put the foot down and it really shifts !
but at idle it runs really ruff! it has a k&n filter fitted (not by me) not sure if it is original?
Any help gratefully received

Cheers keith      

[trebor.vr6.]

What do you mean by ruff. How many revs at idle.? Is there any shake or juddering  

[keithcdb]

it revs around 800rpm but there is a bit of shuddering going on if i am sitting at traffic lights and if i give the throttle a quick blip it drops right down to almost stalling !!

any ideas

[trebor.vr6.]

The idle speed sounds spot on. ?I think your engine is ABF with a multi-point ?injection system. Maybe one of the injecter is not opening and closing at the right time. Try a couple of bottles of injector cleaner when you next fill up the tank. It sound like your engine needs a clean how about changing the oil while your at it. I would suggest a minium of  every 8 thousand miles  possibly less.......!

[Mikester]

Clean the throttle body.

lol

[Deano2711]

+1  Clean the throttle body. My 8v had a similar problem until I cleaned the throttle body Monday night and now it's ok again. It's a fairly straight forward job.     Cheers     Deano

[javalin]

sounds like its running rich - test & change the coolant temp sensor and/or the engine temp sensor if fitted.

[justalex81]

check the vac pipe from the inlet manifold to the ecu it senses the inlet air pressure. if it's knackered then the car will idle like a bag of sh!t

[VW BUSH]

You need Vag Com/Fault computer + Carb cleaner for Mk3's
Then when that fails come on ths forum for abuse help 

[t-tim44]

mine did this as well. its was the MAF sensor. Mine was the hitachi type. Take it out, put boiling water into a bowl, give the maf a quick rinse in it, leave it a few secs and dry it off with an air line. That fixed it! Clean the TB too but as this is the usual problem.