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Model specific boards => Golf mk2 => Topic started by: blu16v on 11 April 2005, 09:53

Title: Violent surging on over-run - closed throttle
Post by: blu16v on 11 April 2005, 09:53

Hi guys, been lurking on this forum for some time now while i have been getting my Ebay valver ready for MoT - new front suspension, antiroll bar bushes, front brakes setup off an early MK3 for the bigger discs, new rear caliper, various new brake pipes etc.

Just picked my '86 valver up from MoT station and it is suffering from violent surging on closed throttle, any ideas welcome. It passed  :grin: so the emissions must be OK, but wonder if he has screwed the mixture to get a pass. :undecided:

It has been stood around with little running for about two years. As you are a knowledgable bunch i thought i would run this past you before i did anything.

Thanks for your time

Title: Re: Violent surging on over-run - closed throttle
Post by: Gambit on 11 April 2005, 09:55

only closed throttle what are the rev's sitting at? sounds like your closing the throttle but the rev's aint dropping?

Title: Re: Violent surging on over-run - closed throttle
Post by: Ant on 11 April 2005, 10:09

Could this be an ISV problem?

Title: Re: Violent surging on over-run - closed throttle
Post by: Gambit on 11 April 2005, 10:29

aye something to do with the ISV operation

likely to be either caused by an air leak or a duff ISV control unit which is usually caused
by a duff throttle switch which fries the ISV control unit.

Title: Re: Violent surging on over-run - closed throttle
Post by: blu16v on 11 April 2005, 10:54

Thanks for the quick response guys.

Gambit, sorry to be pain, could you elaborate on the ISV, what is it? what is does?

Thankx

Title: Re: Violent surging on over-run - closed throttle
Post by: Gambit on 11 April 2005, 11:37

its the Idle Stabilisation valve. basically controls the idle.

here's a pic of it in the engine bay just sits above the dizzy with an electrical connector on the back of it.
ISV location (http://www.golfgtiforum.co.uk/gallery/displayimage.php?album=48&pos=0)

Title: Re: Violent surging on over-run - closed throttle
Post by: blu16v on 11 April 2005, 13:51

Thanks guys, i'll check it out and let you know, will probably be a few days, i'm supposed to be on garden watch/renovation/new path/cut the garss etc.

Title: Re: Violent surging on over-run - closed throttle
Post by: rubjonny on 12 April 2005, 15:24

If it has a throttle switch (were they only on digi models?) check it clicks shut when you release the throttle, and test it with a multimeter to check it is working correctly.

Title: Re: Violent surging on over-run - closed throttle
Post by: Gambit on 12 April 2005, 16:09

it does have a throttle switch.

PM deefadog - he had a post on here a while back about all this. it will explain evverything you need to know about the ISV control circuit

Title: Re: Violent surging on over-run - closed throttle
Post by: monzablue16v on 13 April 2005, 23:34

pls post up here when you find out my isv needs an overhaul me thinks  :sad: