1 step forward, 2 steps back!


Along with servicing my girlfriend's Polo today I decided to try and sort the way the idle would intermittently drop suddenly and the car would cut out.

I spoke to a mechanic friend of mine who said it wouldn't be the TPS as I'd guessed but the throttle butterfly and mechanism would be gunked up and brake/throttle cleaner etc. would sort it.

So I stripped all the airbox away, removed the throttle body and cleaned it up thoroughly.


Put the car back together and now, the idle is much higher than it should be (up to 2500rpm or so) but sometimes randomly lower.

Sometimes it idles at 1100rpm as opposed to the 750rpm or so it was before.

Also, when lifting off the throttle the revs drop slowly and by random amounts as opposed to 'snapping' straight down to idle.

I also changed the air filter and spark plugs.



Anyone got any ideas that could help would that be brilliant!

Thanks!

James

[Edited on 31/1/10 by James]

You havent got an airleak have you?

maybe you messed up the AFM sensor while cleaning?

Theyr very common to have a leak on the throttle body and cause alsorts of weirdness.

I have a 1.4 TC (75) golf, and this happens every 15k miles or so. It is a carbon buildup inside the throttle body, it blocks the tiny little bleed holes which allow the airflow when the throttle is shut. I upsets all the sensors which get signals they are not expecting.

The cure is a few spanners, an old toothbrush and a big tin of carb cleaner and about 45mins of your day.

When we bought the 1.6GL 1995 the throttle was doing weird things, after a while it got so bad that the revs would just go up and down up and down by about 3000 RPM... turned out the TPS in the throttle body was shot (a fairly common issue apparently)... got it replaced under waranty and the problem went away..

[Edited on 31/1/10 by tegwin]

Woohoo!

Fixed!

I stripped it all apart again. Spent a bit longer with the carb cleaner on the TB (and made sure the butterfly was spotless and in the right way round (it was).

I even dismantled the throttle pot, saw a world of spring and gear related pain, checked the wire continuity and put that back together rather quickly!

I removed the TB gasket and cleaned it (should be replaced according to Haynes but it was still pretty 'rubbery' ) and cleaned the gunk out of the grove the gasket sits in.

Started the engine and all was then ok.

I did up the TB more tightly (in case airleak around it) and then just put everything else back, one part at a time and started the ignition each time to see if anything else caused the problem.

Nothing broke it again so I assume all is fixed.

I can only assume I'd not fitted the TB back properly when cleaning yesterday, the gasket was not sealing properly or maybe the butterfly had a problem.


Thanks for the help everyone!

Cheers,
James

[Edited on 31/1/10 by James]