Volvo 480 Club Europe

Hello, I have a 480 Turbo of 1992, when cold start the rpm remain at 600 and the car vibrates but once the engine is warm the rpm remain at 800-850. I have tried to disconnect the idle control valve with the car warm and the rpm stay the same with no variation, I have also checked the resistance of the valve and it is between 20-40 Ohms. What should I look? Because spark plugs, distributor cap and rotor, ignition cables and temp sensor are new.
I also cleaned the idle control valve but with the same result.
Also tried to start the car with the idle control valve disconnected and the rpm go up to 1200 but tried to repeat with no luck, with the idle control valve connected and disconnected the car has the same 600 rpm on cold starts.

Can you interrogate the diagnostic port?

The diagnosis port doesn’t work

Idle control is managed by the Jetronics ECU and starts when a switch under the throttle body connects a wire coming from this ECU to mass. Apparently this is working at higher temperatures. The throttle cable may be too tight and prevent the switch from acting at low temperatures. Loosen it a bit and see what happens.

I had this years ago with my old 480, it was the valve that runs from the control valve round the right hand side of the engine, no idea what its called, not even sure if you have the same engine or year as mine but it solved the problem for me though. This post might help..

viewtopic.php?f=11&t=12966&p=201561&hil ... rt#p201561

Make sure the idle control valve is not bypassed by the bullet plugs being connected.. They are on the same loom as the horn and plug for the idle control valve on my car..

Hi,
I agree with Rachel. the most probable culprit here is that diaphragm valve just before the ICV. Those give all sort of issues. Even if it has not gone bad, I would suggest replacing with a 710N valve.
I had a very similar issue (if not the same) in the past. Take a look at Rachel's link You'll see me there

The reason why disconnecting (or earthing) the ICV does not make any difference is because in your case there is not enough air reaching it in the first place since that diaphragm valve is closed.

The reason why the car seems to idle correctly when warm is because that small pipe that connects from the turbo inlet to the cranckcase breather has a valve which opens when the engine is warm which allows more air. I'm not entirely sure about this one but makes sense to me.

The good news: the valve is cheap.
The Bad news: it is not a direct fit. You'll have to adapt the pipe that comes from the turbo.

Hope it helps. keep us posted.