Valver idling problem, SORTED!!

[skinnyman9000 0]

I've ran a search on this but it all seems to be with cars that are struggling to idle and cut out, mines the other way around!

 

I've replaced the throttle cable and adjusted that accordingly, so i know that isnt the problem. Basically i start the car and it will idle at just above 2k rpm. Now it used to do this anyway, and a quick blap on the throttle would bring it back down to 1k rpm, but that is no longer working. So, does anyone have any ideas? The weather might not be helping as the warmest its been here for a few weeks is 3deg, and the car hasnt been started for about a month, so its constantly been cold for a while now. Also its still running cheap local garage oil from when i had the oil leak as i havent had the chance to get some decent stuff put in it yet.

 

Anyway, anyone got any ideas?

[davidwort 0]

sounds like classic duff idle valve, try one off another car to rule it out, although not a perfect fit where the bracket supports it, a mk2 golf gti or passat 8v one will connect up and operate correctly, possibly some of the mk3 and audi ones too, providing it has the same basic long metal body and the electrical connector fits.

Cleaning them doesn't always work.

[skinnyman9000 0]

Do they just randomly break then without any prior warning? Because one day it was fine, the next day it wasn't. Originally when i started the car it was fine, 30secs into my drive the revs picked up on their own every time i dipped the clutch to change gear, and when i lifted the accelerator back up they dipped off again, hence why i replaced the throttle cable. Now ive replaced the cable it doesnt lift the revs on its own (altho i havent actually driven it to make sure, due to the high revs). I suppose the best thing to do would be to take it for a spin round the block, to make sure the initial problem of the revs climbing on their own is gone, so at least i know the replacement of the throttle cable has sorted that problem.

 

I dunno, it was off the road for a week whilst the rear brakes were sorted, then 30secs after that job something else breaks!!

[davidwort 0]

from your comment about blipping the throttle to settle the revs I read that as the valve starting to play up, the other thing to check is that the idle circuit is being switched on, there's a micro-switch on the throttle body that does this when the throttle is in the shut position, sometimes the mechanism gets gunked up and the switch doesn't quite get pressed, you could also check if the switch is actually operating with a multimeter/test light.

[skinnyman9000 0]

Your comments are perfectly inline with what my mate at work has said (also a corrado owner) so it would seem the next thing to do is sort that out tomorrow. Im going to try everything before replacing the ISV i think.

[skinnyman9000 0]

Ok, had another play today, and it goes along a little something like this.

 

Step 1, the throttle housing is in this position:

Although you cant see it, the stop is on the switch in circle one, and in circle two the throttle is resting against the correct stop.

 

 

Step 2, i start the car. It idles at just under 2,000rpm. So i begin to move the throttle. Now instead of moving to the other stop immediately i have to move the throttle round approx. 20mm, then the throttle 'snaps' to the other stop, like so:

 

 

 

Step 3, i now let go off the throttle. The throttle does not return to the other stop as it should do, resulting in this:

Now the car is idling at 3,000rpm, obviously because the throttle has not returned to the correct position.

 

 

 

Step 4, this is where it goes odd. I push the stop back onto the switch, so the throttle returns the position that it should be in, like so:

 

 

Now with the throttle in the correct 'rest' position the revs drop, BUT, the revs raise and drop between 1,000 and 1,500rpm, it just keeps going up and down, up and down. Then when the move the throttle again, it doesnt hit the switch properly, so the car idles at 3k, then when you push it back onto the stop it idles up and down again

 

 

 

SOOOOOOOO, what the hell is going on?!?!? Obviously there is a problem in the throttle housing somewhere as it doesnt return to the correct position. But then when it does, the revs are very strange.

 

Any ideas?

[G60SC_Stoney 0]

i'd say you need to de-gunk everything and clean it up, there must be some muck stopping it going back to the correct position. get nvolved with loads of engine degreaser and wd40!

[skinnyman9000 0]

i'd say you need to de-gunk everything and clean it up, there must be some muck stopping it going back to the correct position. get nvolved with loads of engine degreaser and wd40!

 

Take the throttle housing apart etc and degunk all that? Reckon that will sold the random idling problem? Or am looking at replacing the ISV for that one?

[easypops 8]

I'd also be looking at the throttle position switch or more likely the wiring that goes into it.....on mine my bad idle was caused by 2 broken wires on the plug that connects to the throttle position switch.....not easy to spot though as the plastic sheath was still intact.

mine is a 2.0 16v but the info i have here says you have a similar throttle setup......i'm sure someone will correct me though :D

[G60SC_Stoney 0]

i would take the whole thing off and give it a good clean and degrease, then put it all back together. maybe put the whole assembly in a washing up bowl and liberally spray it with engine degreaser, give it a scrub with a toothbrush or similar, try to remove as much gunk as you can and leave it an hour or so, do the same again, check all the contacts are good, apply a bit of WD40 and refit.

 

at least this way you know there is no grit/dirt stopping it pivoting/returning to its correct position. at the end of the day its covered in years and years of engine bay/road filth, which is bound to hamper its performance. my G60 assembly was the same...

[jonesyUK 0]

If that doesn't cure the idle going up and down I would refer you to my experience here with very similar symptoms to yours, although my throttle wasn't sticky. Have detailed all the things that were eventually replaced on pages 14 and 15.

 

viewtopic.php?f=1&t=47311

 

Have you had a diagnostic done to see if there are currently any electrical faults?

[skinnyman9000 0]

I think the first step is to clean and de-gunk everything throttle related. I have a mate at work that has a rado, currently off the road, but with a working ISV, so i might borrow that just to rule that out of the equation.

 

I cant see it being anything more severe to be honest, i had a full engine rebuild last than 3,000 miles ago, so i cant see it being anything injector related. Judging by the 15 pages in the above thread though i can see this being fun. Looks like ive paid another 6 months road tax for 3 months use of the car :(

[skinnyman9000 0]

SORTED!

 

I took the ISV off, left it in some petrol for an hour then gave it a bloody good clean with come carb cleaner, stuck it back on and job done! Fired up the car, nicely idles at 1k, not lumpy or too high, so job done!

 

I also took the throttle cable arrangement off, cleaned it all up, and played with the adjustment, thats sorted too.

 

Cheers for the help guys!!