Hmm, lumpy idle after changing Idle Control Valve
 

Bit of a curious one this if anyone has had a similar issue.

Earlier on I removed my idle control valve off my MY99 UK wagon. Was giving it a clean with some carb cleaner and I bust the bloody thing :Whatever_

So faffing around I managed to source one off a mate tonight and have just fitted it maybe an hour ago. Beforehand I also gave this one a clean with carb cleaner. It took a couple of goes to start up which I thought maybe due to the cleaner.

Anywho she fired up and I took her for a drive to see if all was well, only a few miles around town. Even when warm, the symptoms I have are the following...

1. When dipping the clutch at junctions etc., the revs drop right down to about 400rpm before picking up (before she was warmed up, it just about stalled but not quite).
2. When leaving to idle either with the clutch dipped or in neutral it seems to be idling quite lumpily (word?) between 700-900rpm, going up and down, up and down.

On the other ICV (the one I bust), it idled fine usually around 750-800rpm.


Is it a case of the new ICV just bedding in, or does it need another clean perhaps? Or does my problem point to something else? There's no engine light on or any codes etc.
If it makes any difference, my mpg recently hasn't been great (18-21) so I unplugged the MAF earlier and the engine spluttered away not quite cutting out.

Thanks,

Andy :)

That's usually indicative of the MAF being knackered isn't it? :wonder:

If the MAF's knackered, it would cause idle problems. However, it could be a vacuum leak, give your pipes a good check my good man. :D

did you check voltages with a meter? might just need setting up

Hi Matt, this is what I was doing yesterday before buggering my other ICV as I have some spare silicone pipe. I was looking at just replacing what I could but I don't think there are any leaks.

No mate. How do you mean setting up? I always thought the ICV was self adjusting with the spring inside it?

Well today I've put another known working maf on and she seems to drive ok and more smoothly BUT still has this god awful idle when warmed up and dipping the clutch when in gear.

I'm going to try another s/h idle control valve off a breaker on here to elliminate this part then if it still persists it maybe time to take to a specialists. Not found any air leaks etc. and she boosts fine.

So you car was idling fine and you decided to take the icv out to give it a clean, if it ain't broken and all that.
Not a very constructive post I know.
My early classics icv was fitted with 2 screws through slots, with this you could turn it which would effect the tickover speed but I don't think it will smooth out lumps. As for checking voltage I thought that was just for setting up the tps.

:lol1:

No worries mate as I know there's no malice or 'I told you so' in your post. The reason I took it out to clean was the idle took a while to drop to general tickover, which having read up was a sign of being clogged up. :)

Have you triued adjusting it Andy? Mine is adjustable. I watched Bob adjust it once, but can't for the life of me remember what he did fully, except loosen two screws and tap the valve one way.

It's not mate, no. There's nothing on it to screw in/out or adjust it depart from physically pulling on the spring loaded valve.

I've been suggested to disconnect the battery for a few hours in order to reset the ECU and then take it for a drive. If that doesn't work I will try one more ICV and then speak to a garage about it :)

Mine doesn't LOOK adjustable.......

there are two phillips screws on top of the icv slacken them off and you can move the top of the valve left or right:)

Are we talking about adjusting a pre 99 IACV which is on the rear passenger side of the intake manifold. Or adjusting the post 99 IACV which is located near the throttle body, I know that the pre 99 has 2 visible screws for adjustment but not so sure of adjustment on post 99.

Cheers Iain

There's nothing there to use to adjust.


Not on a MY99-00 ICV

:thumb:

IIRC if you get a multimeter and a pinout diagram for the ecu and measure the voltage across the ICV wires you should be looking for 0.47V with the engine at idle. Which should give you around 750rpm. Pinout diagrams for ECU's can be found on jolly green monsters website.

Mike

Is the O ring seal that seals the IACV in it's housing in good condition?

The smallest of air leaks there would upset your idle.

Cheers Iain

Yep, all in one piece and not deteriorated.

I presume there's no gasket that sits on the throttle body to IVC face is there? Sits flush anyway but just asking incase.

I've disconnected the battery and manually locked the car up for a few hours. See if this resets the ECU and makes any difference to my issue. :thumb:

Well this is a curious one. After receiving a pm from mattybr5@poleposition as I'd contacted him re. another ICV recommending to disconnect the battery for a few hours, the issue has (currently at least) gone :freak3:

Took her for a drive earlier to Asda andwhen warmed she dipped to approx 600revs a couple times but then sat idling away around 750-800 with no heavy fluctuating like before.

Hmm, strange indeed :D

When we change IACV on the impreza's we carry out a dealer check mode procedure which sets everything up as it should be, This can only be carried out with a select monitor though.