Struggling idle when cold. Bad WUR?

[dub be good to me]

Finally had my mixture set properly and now it (Kjet CIS 8v) doesn't want to idle when it is cold (before when it was running really rich the WUR would kick the revs up to abt 2k).

Before I lash out on new (or 2nd hand?) WUR is there anything else I should be checking?

Note: Once it gets warm it idles perfectly.

[h100vw]

Is the bypass valve fully open. Can't remember where it's located off the top of my head.

If the engine revs up willingly, the WUR is probably OK and the tickover needs increasing.

Gavin

[dub be good to me]

Is the bypass valve fully open. Can't remember where it's located off the top of my head.

If the engine revs up willingly, the WUR is probably OK and the tickover needs increasing.

Gavin

By bypass valve do you mean the auxiliary air valve?
From my understanding, when the engine is cold the auxiliary air valve bypasses the throttle valve allowing more fuel and air mixture into the engine. So what you're saying is if this bypass valve isn't opening fully, then it won't be getting the full dose of extra fuel/air mixture? How do I test it?

EDIT - Nothing like answering your own question - Aux Air Valve Testing Procedure

The engine revs up, but when cold staggers a little. What does tickover mean?

[dub be good to me]

Ok, so I quickly run outside to give the Aux Air Valve the pinch test (pinch air pipe up to aux air valve) and found the following:
-the hose was already bent flat in two spots (due to bending straight pipe into necessary 'S' bend).
-when I straightened the closed sections to allow for better flow (by hand) it made no difference to low cold idle.
-when I squashed the flat bends further (again by hand) it again made no difference.

Next step is to replace crappy pipes with a more suitable replacement & take Aux Air Valve off and see if its fully opening.

Will post results.

[roccodingo]

Check the aux air valve when cold , also check the thermo switch .

looks like this



Should be an electrical test proceedure in your manual.

[h100vw]

Tickover is idle speed mate.

There is a screw in the throttle body, you need to wind it out a bit. It should be set when the engine is warm.

The Aux air valve lets in extra air, the fuel goes up because the flap in the air flow meter is lifted further.

A weak mixture could drop the idle and make it hesitant. WURs cost money though. So I would check everything else first.

Gavin

[Golf Loon]

Thermo switch controls the 5th injector. The test for that is to put power to the 5th injector, you should hear it click. Do that when the car is cold and see if it starts better. If so, I`d change the thermo switch.

Expensive in Oz, cheaper O/S.

[dub be good to me]

Tickover is idle speed mate.

Of course! Terminology fail

There is a screw in the throttle body, you need to wind it out a bit. It should be set when the engine is warm.

A weak mixture could drop the idle and make it hesitant.

Cheers, I've already tried bumping the idle and mixture up, but it either idles to high or ends up far to rich (when warm).

The settings I'm at now (when warm) idles at about 900 and is a touch less (i.e. more rich) than 14.7:1.

Check the aux air valve when cold , also check the thermo switch .

Thermo switch controls the 5th injector. The test for that is to put power to the 5th injector, you should hear it click. .

Looks like I've got some testing ahead of me, I'll post when I've sorted it out (or have hit another wall )

Thanks all!

[h100vw]

The fifth injector only runs for a few seconds, if it won't tickover, I don't think that's it.

Gavin

[dub be good to me]

It's a bad auxiliary air valve.
I pulled the hoses off and had a look through (while engine off and cold) and the valve was almost completely closed. I gave it a wiggle with a thin screw driver (to see if it was just sticking) but it sprung back to being mostly closed.

As a final test I bypassed the aux air valve (by connecting air pipe from in front of throttle body straight to where the aux usually connects to the manifold). When I started it, it jumped up to a healthy 2k.

What's the cost of a new unit? Anyone have a good 2nd hand one of these?

Thanks all - group knowledge rocks