high idle

[Rick 0]

wen i first start my corrado (1.8 16v) it idles lovely around the 1000rpm mark but i take it 4 a drive it idles around 2000rpm any ideas?

[CaiosG60 PWR 0]

idle stabilisation valve????

[Rick 0]

were is that located in the engine bay and is it expensive cheers mate

[stevemac 0]

Had a similar problem with my old Scirocco 1.8i - similar mechanical k-jetronic injection system.

 

Turned out to be a sticking throttle cable. When your engine is idling at 2000rpm, lift up the bonnet & check the cable is releasing properly. Cable & mechanism should be either on top of or at the back of the cam cover, next to the thottle housing on the inlet manifold.

 

Could also be a 5th (cold start) injector problem or a problem with the "warm-up" regulator - part of the cold start system. Quite common with this type of injection system.

[Kevin Bacon 5]

The Idle valve is the metal tube with Bosch written on it next to the distributor. When the engine is next idling at 2K, try hitting the ISV with a hammer. If the idle slows down again, the ISV's internal valve is sticking. In which case you can either clean it out with carb cleaner or replace the valve, circa £100.

 

Also, as Steve said, check the throttle cable because if it's snagging, the microswitch on the throttle body won't activate, and therefore neither will the ISV circuit.

 

Kev

[ben16v 0]

is there any way to adjust the tension on the spring as mine and my missus` dont quite touch the microswitch!!

[Kevin Bacon 5]

Nope is the short answer! There is a very small grub screw on the throttle body which sets the throttle butterfly stop position. Try adjusting that until the switch triggers. The yellow blob of paint on the threads indicates it's still in it's factory setting. No yellow paint means it's been tampered with.

 

K