Revs not dropping between gears

[hughesy83]

Hi,
I bought my first mk2 16V not long ago and am having fun to say the least!

Unfortunatley tho now i've now got a small problem with the revs not dropping back to idle between gears, and wonder if anyone here could offer advice.
As an example, if i'm driving along the motorway in 5th at 70 and depress the clutch, the engine still runs away at about 3200 rpm and doesn't drop in speed.
If then I approach a junction or whatever and have to stop, the only way to drop revs and not sit there sounding like i'm revving the nuts off my car in an attempt to impress the ladies in car next to me, is by engaging clutch again and forcing revs down. But once they are down, they dont rise back up by themselves - they just seem to get "stuck" up there.... this can happen in any gear...

I was wondering if its the ISV unit? although other stories i've read on here RE: ISV mention either erratic idleing or revs dropping below 1000 and stalling so i'm wondering if something else is up with my car?

And btw i do take my foot off the throttle lol, and don't think its a sticky throttle cable as i can drop the revs using clutch as mentioned above...

Cheers for any advice...
Hughesy

[Wayne]

Is your clutching slipping.

[jezza16v]

Could be the idle switch on the throttle body is not operating when you take your foot off the throttle or the isv sticking. Just had this exact prob on an 8v digi and it turned out to be an intermittent isv fault, replaced the isv and it was sorted. I know the 16v kjet is is different but I think the ISV works in exactly the same way. On the 16v there's a separate electronic control box for the isv behind the centre console but I've not heard of these going wrong very often. Always worth cleaning the isv out with some carb cleaner, there's a guide on here somewhere.

[VeeDubGTI16v]

sounds throttle related. whats the cable like? it might be frayed and its sticking at this point, on the springs and linkages are sticking.

i had the same problem when i put an abf in mine, the top of the throttle linkage was jamming on the bonnet 

[fishnchipsx2]

Try unplugging the ISV - idle will be pretty rough, but if it stops revving, that's your problem!

[hughesy83]

No clutch isn't slipping.

I'll try unplugging the ISV now and see what happens... thanks for the tips!

[hughesy83]

Any idea what this is? Its been attached to my ISV using a plastic tie clip.
It appears to connect fuel lines and a sensor (temp?) But i'm pretty sure this isn't how car left the factory. Any idea's on whats going on here? Thanks

[jezza16v]

Looks like some sort of by-pass or piggy back on the warm up regulator, perhaps to enrich the mixture for some reason. Perhaps the cams or timing are not standard?

[Gambit]

you can test your throttle switch by hand, with the engine running open the throttle by hand to over 2k rom, press the button on the throttle switch and hold it. if working it will activate the bypass valve and the rev's will temp plummet then lift again. it will do this continually for as long as you have the button pressed. if it dont do it, the switch is goosed

[DarnPB]

Have your brakes got harder lately? Check the NRV between the brake servo and the induction and also check the interity of the servo pipe. Any leaks there may cause the symptoms to have.