HELP Idle control valve question

[ThePurplePanther]

Help oh great and generous collective font of brickish wisdom...

I have a stubborn Lambda light, fault code read it and all points towards an idle control valve issue (plus the car doesn't have a great idle)

So i pulled it to clean it, and the throttle body while im there, but on inspection the rotating bit just seems to be flapping around inside.

So my question is, do these valves have two way electronic adjustment, or is it like the 940 one - i am more used to the simpler world of 940s atm, new to 960s - where the centre part is held closed by a spring and opened with the application of the voltage.

TL,DR - should the central 'spinny bit' on a 960 idle control valve be pressing against an internal spring, or should it be free spinning?

Car is a 1995 960 2.5

Many thanks in advance

PP

[Laird Scooby]

That Idle Control Valve doesn't sound healthy Phil, worth swapping for a known good one to see if it puts the EML out. As far as i'm aware, the centre part of the ICV is the bit that moves, depending how it's made either in and out to open up and close down an airway or if it's the disc type with a varying width slot, should rotate but only under motor control.

The other one you describe is an Auxiliary Air Valve. Basically a plate on the end of a bi-metallic spring that bends when it gets warm from the current passed through the heating element inside the valve body.
When the bi-metallic strip is straight/cold, the air channel is open, as it heats up, it bends and closes the air channel.

Not sure if that actually answers your question but i hope so!

[TonyS9]

I'd guess that if it is like a servo it would need 3 wires, otherwise it needs to open against a spring. The 940 is 2 wire as you know, what is the 960?

[mjk164]

I think from what you describe, the ICV is shot. On a 960 B6304 engine, the center part should rotate against light spring pressure and the position will be set by the stepping motor that is part of the valve, getting its signal from the Bosch Motronic engine management system. I think that all ICV's used in the 960 series have a black plug on the side with 3 wires, but that does not matter if the internal spring is broken, which is your symptom. Change the ICV. Before you finish, make sure the throttle body and butterfly are clean and the 2 vacuum holes in the throttle body towards the rear, are clear. Lastly read any fault codes and then clear them.

[ThePurplePanther]

Thanks all - agree it is shot, just wanted to check it was supposed to spin against a spring as all the others i have played with on other cars do.

Ordered a known working 2nd hand one so fingers crossed it will sort it.

Was just loathed to splash out on a new one (have you seen the price!!!) if i didn't know it will fix it, if hte 2nd hand one sorts it i will consider gettign a new one at some point as all the original ones are now 20+ yrs old.

Fingers crossed

PP

[mjk164]

I'm sure the 2nd hand one will be fine; just check its clean by spraying some suitable cleaner into it (WD40 will do), and just make sure the inside rotating valve is going against light spring pressure. Don't forget to clean the throttle, butterfly and vacuum holes and then read and reset/clear the ODB; that's important.
My 1993 960 has done around 380,000 miles and still on the original ICV....just have to keep it clean!
Good luck.

[ThePurplePanther]

Funny you should mention that, spent today cleaning up the tb - while it's apart I will clean as much of the inlet side as i can.

Thanks all

PP