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Author Topic: car cuts out when you let the revs down  (Read 5241 times)

Offline aaron1980

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car cuts out when you let the revs down
« on: 19 May 2009, 21:36 »
Hi i have a mk2 gti 16v it drives fine and pulls very well. the problem i have is when you let off the throttle if you dont ease it off the revs drop wright down and the car cuts out. someone said it could be the idle valve, does anyone know if i can use the idle valve off of an 8v golf or know anywhere that i can get one that will work or dose anyone have any otherr idears as to what is wrong with it.
when i got the car i fitted a new head gasket had the head skimmed and re seated all of the valves the compression is ok and the car drives fine other than the problem i have said about i would be gratefull of any help thanks Aaron. :grin:
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Offline Conker

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Re: car cuts out when you let the revs down
« Reply #1 on: 19 May 2009, 22:52 »
Hi.

IIRC, the 8v ISV is different to the 16v, but you can use a k-jet ISV from a Corrado or I think the 16v Mk3 Golf ISV is fine too.


Some other suggestions...

1) Clean the ISV very well. I use WD40, sprayed into the two holes, shake and rinse. Repeat several times until the WD40 comes out clear.

2) Remove and clean the idle screw in the throttle body. Is the rubber o-ring around it perished maybe?

3) Reset the CO2 and idle setting (http://www.golfgtiforum.co.uk/index.php?topic=22031.0).

4) Unplug the overrun cutoff valve and see if that helps. Perhaps try cleaning it out with WD40 too.

5) Check for air leaks.

6) How old is the fuel filter, can you hear the fuel pump prime on startup etc. etc.


(My bet is on No.3)
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Offline neils

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Re: car cuts out when you let the revs down
« Reply #2 on: 20 May 2009, 00:03 »
plastic valve behind the airbox trust me clean it with brake claner or petrol or any thing to flush the sh!t out. i've been there, i've got a 16v gti and had this problem for ages, tryed replacing the isv and adjusting the timing and co, no good (to me). i've seen so many people on here goning on about this problem and i keep saying the same thing, but belive me try this before replacing things it's gotta be the cheapest option. let me know how you get on i'll hang my head in shame if it dont sort it out. :wink:
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Offline Conker

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Re: car cuts out when you let the revs down
« Reply #3 on: 20 May 2009, 01:24 »
Quote from: neils on 20 May 2009, 00:03
i've seen so many people on here goning on about this problem and i keep saying the same thing...


A strange thing to say when you've got a post count of just 13?


And I guess you mean the over-run cutoff valve, which I mentioned in my post above. Unless you mean the pressure valve (flying saucer shape) behind the airbox.
« Last Edit: 20 May 2009, 01:27 by Conker »
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Offline gavL

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Re: car cuts out when you let the revs down
« Reply #4 on: 20 May 2009, 01:29 »
Got the same problem but on  an ABF, off to the Mk3 forum with me :(

It happened today and the battery didn't have enough charge to start up again...
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Offline rubjonny

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Re: car cuts out when you let the revs down
« Reply #5 on: 20 May 2009, 09:09 »
this is the job of the over-run cutoff, make sure vac lines to it are ok, and check the yel/black wire has 12v with the ign on (its earthed via the isv control unit) also check the extra red/black wire to the coil is connected without it the isv control unit is in 'setup' mode and cant trigger the over-run to catch the revs.

If you put 12v to the overrun cutoff valve you should hear it click, if it doesnt, bin it.
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Offline aaron1980

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Re: car cuts out when you let the revs down
« Reply #6 on: 20 May 2009, 10:30 »
Hi thanks to everyone for there help im just off down the workshop to see if it works i will let you know how i get on in a bit. thanks again :grin:
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Offline neils

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Re: car cuts out when you let the revs down
« Reply #7 on: 20 May 2009, 11:46 »
Quote from: Conker on 20 May 2009, 01:24
Quote from: neils on 20 May 2009, 00:03
i've seen so many people on here goning on about this problem and i keep saying the same thing...


A strange thing to say when you've got a post count of just 13?


And I guess you mean the over-run cutoff valve, which I mentioned in my post above. Unless you mean the pressure valve (flying saucer shape) behind the airbox.

ok ok i'll change that to i keep thinking the same thing  :wink:
i think it's the pressure valve i'm on about. i'll have to get a pic of it.
« Last Edit: 20 May 2009, 22:49 by neils »
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Offline aaron1980

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Re: car cuts out when you let the revs down
« Reply #8 on: 20 May 2009, 22:46 »
Hi i have checked the isv valve as stated in the post where when the car has warmed up i disconected the breather pipe the the air box and bloked it and the revs stayed the same there is no (buzzing) coming from the valve so i think i will need a new one anyway i will try to get a new one tomorrow.
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Offline Conker

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Re: car cuts out when you let the revs down
« Reply #9 on: 21 May 2009, 23:01 »
Quote from: aaron1980 on 20 May 2009, 22:46
...there is no (buzzing) coming from the valve so i think i will need a new one anyway i will try to get a new one tomorrow.


Remember its not a loud buzz. Your better off touching it while its on and it will be tingly (ooh err!!).

Before you splash the cash on a new one check that your getting volts through the wire to it - theres a possibility it might be dodgy wiring.

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