Idle Speed Control Valve - High idle problem

[Mike P]

The 16V is running slightly too quick at idle when warm, about 1200rpm.

I suspect either the Idle Speed Control Valve or the ECU temperature sender on the thermostat housing.

Bought a Bosch valve from Eurocarparts for £85 all in.

The application listing is correct and the manufacturers part number is the same as the one on the car, 0 280 140 516.

Started the car up and it ran at about 1100rpm. Fitted the new one, started the car and it idled at 2500rpm

Tried this twice with the same result and the idle would not drop down.

Am I missing something obvious in thinking it is a bolt on replacement that doesn't need calibrating or setting up.

The valve does a small brass screw on the side but this is covered in a tamper proof resin and so I didn't touch it.

Mike P

[jayw]

Here's the new one i bought, works perfect, check the p/n:

[NZ16v]

How long did you leave it running? The dumbass computer needs a bit to register that something has changed, and goes into some kind of base mode, before resetting itself with the new part... didi it on mine when it was freshly rebuilt, and Dad assured me the computer would settle the car down, as it revved its tits off, and i ran around like a headless chook...

...and it did!

[Adrian E]

Might also be worth disconnecting the battery for 10 minutes to force the ECU to reset (assuming it's clever enough to remember anything/learn in the first place!)

[Mike P]

I've never had to change an ISCV before.

I had the car running for maybe 10 seconds with it screaming away at 2500rpm idle.

Would this be the recommended approach:

Disconnect battery.
Fit new valve.
Leave for 10 minutes.
Start car.
Let idle settle down.

Mike P.

[prm]

If the high idle speed remains with the new unit fitted? Try removing the CTS plug and bridge a 4k resistor across the pins, then try 2k, to see if there is any alteration with idle rpm.

Check the resistance on the new unit, should be approx 8Ω at approx 20°C also the resistance on each injector match.

Regards

[Mike P]

Sorted:

Didn't disconnect the battery as I don't believe the ECU is that sophisticated. Ran the car for 5 minutes with the old valve still fitted to warm up and push the oil round the engine.

New valve fitted and it starts up at 2500rpm. 5 minutes later is slowly settled down to 1700rpm. Switch off and start again, 1700rpm settles down to 1200rpm after another 5 minutes. Switch off and start again, 1200rpm now becomes 1000rpm - getting there slowly

Took the car to the local garage for them to check that the emmissions were now correct and found to be running a bit lean, so the mixture pot on the AFM adjusted.

Here the embarrassing bit: I dropped the hose clip that clamps the pipe to the ISCV that comes from the inlet hose and couldn't find it so I decided that I would buy one on the way back from the garage. 20 yards from the garage this pipe has worked loose and the car stalls and won't start, with a long line of traffic building up behind me. Pushed into the church carpark next to the garage and I have to walk in and get a hose clip from the stores to clamp the pipe and close the air leak.

Once this hose clip was on and the mixture adjusted, the car now has a nice stable 900rpm idle again

Mike P.