right my cossie idles fine when its warm and you disconnect the idle speed control valve connector plug. but as soon as u plug it back on the idle jumps up high ans starts going up an down an hunting kinda thing.

and when u pull it off again it sounds fine. and idles on the first line up on the rev counter think it stands for 750rpm.

anyone know whats up with it?

i'm trying to get a nice clear idle sound which is constant from my car. I only get it with idle control valve disconnected though, but i know i need to use my idle control valve for winter cold starting up etc, so need to get it working properly

cheers

 

TPS problem normally.

 

do they get dirty and need cleaning up? thats the red box on the side of the throttle body right?

my secs monitor reads 0% on idle, when i blip the throttle it increases in percentage then i let go and it drops back down to 0%

Also when i rev the car and let go of the accelerator pedal it bounces back up and it sounds like its getting a eletrical pulse or something coming through as the revs drop down to bounce back up. then it continues idleing abit hunty kinda thing. its not really bad hunting, but it does do it. Mate said its might be because of the high lift cams bd14 and bd10. But it can't be that cos it idles constant when the idle control valve is disconnected.

cheeRS

 

Yes that's it - red D shape thing stuck to the side of the throttle body. TPSs don't get gunked up as they're sealed (unless it's been broken ) - what normally happens with them is the tracks inside wear out and you get a zero reading in some places, normally exhibited by a hesitation or lack of power at a particular throttle point, including 'none'. WIth the ignition on but engine off you should get a smooth change in reading from zero to full (as you press the throttle pedal) on your monitor - if it works when the engine's not running anyway.

Your ISCV could be clogged up with crap - do you have a spare to try it with? if not, whip it off and soak it in carb cleaner.

When you reconnect the ISCV while the engine's running, it will rev high, up to 2-2.5k then settle down, and try to control the idle depending on engine load, cold start (read from coolant temperature), etc.

If it only 'hunts' while it's connected it's probably the valve getting stuck, so the ECU tries to open it wider, until it opens, then it sees the idle too high when it pushes past the resistance, closes it right up, then does the same again, etc etc. Clean the valve out to at least rule it out.

 

ok just had a look at it quickly and done as u said with ignition on oressed accelerator pedal and it goes up nice and comes back down nice and smooth on the secs monitor.

I have noticed something else recently aswell whilst idling. The car was idling and the reading of 950rpm 900rpm sometimes it was coming up with nothing 000rpm, then u drive and it starts working again.

what could cause this to happen?

 

Sounds like your TPS is probably OK.

It's more likely that you need to have words with the ISCV, which is only held down with two screws and a retaining 'ring'. Pop that off and leave it connected - get an assistant to turn the ignition on (but not start the engine) and watch the piston(?) - it should move in and out quite quickly, and you should hear it ticking as it moves. If it does that OK, it's probably OK but just needs cleaning. If it doesn't move it's either completely gunked up or knackered. Either way, disconnect it and take it indoors - spray some carb cleaner in it and watch the black gunk dribble out give it a couple of shots and leave it to dry for half an hour and refit it. Don't lose the screws or retaining ring

My rev counter started doing that a while ago - now it's 'off' more often than it's on , and will drop down to zero from any speed, randomly. It's a gauge fault normally, or could be a poor feed to the counter. As yours comes back up again when the revs pick up it's more likely a loose/poor connection than a gauge fault.