K-Jet Idle 8 valve

Having issues with my K-jet hunting when cold, not much but annoying!

I reset the microswitch last night as this wasnt clicking when the throttle was closed (is this correct??)

Now the problem seems worse revs vary from 1300-200 nearly cutting out, the micro switch controls the ISV correct? this is clicking on and off but not working smoothly maintaining the revs.

Should the micro switch be on/in when the throttle is fully closed?

Thnaks... going mad!

 

The switch should click as the throttle opens, so should be off when throttle is closed

 

What's your idle CO like? Might be worth getting it checked, I had a similar problem when mine was way too rich at idle.

How the ISV works varies a little between models I believe. It should be trying to keep the engine idling between 700 and 1200 rpm, but if this is impossible due to wrong mixture/timing/vac leak etc it may keep clicking on and off in an attempt to make it run smoothly.

 

8V K-Jets don't have an ISV, unless you mean the aux air valve on the inner wing?

 

That's the one. Opens up if the idle speed drops below 700 rpm, then closes if it rises above 1200. Some cars have two, depends if it has aircon fitted iirc..

 

Yes thats the valve, had another play tonight thinking it could be fueling the timing is spot on think its running lean on cold so going to try the 16v WUR tomorrow when i have some longer bolts the vac advance should help the mixture on idle.

The CO was spot on at the MOT in June...

 

Yes that the valve...

Been sugessted by a friend lean fueling at idle, going to try fitting my 16v WUR the vac advance may help with the fueling at idle.

CO was spot on at the MOT in June.

 

I don't think the WUR vac advance will do much at tickover, iirc they richen the mixture at wide open throttle, the 8v didn't have vac ports on their WURs.

Have you tried increasing your idle speed with the screw on the throttle body?

 

Yes rest the idle.

It will run fine for the first 90 seconds and as soon as it starts to warm it will hunt and the revs fluctuate between 1200 and 200...

Once warm is running fine idle's at 900rpm

Wondering if the Aux air valve is at fault is clicking on and off though!

This is a 1900 TSR but should'nt really affect anything unless its the cam!

 

You could just pull the electrical connector off the aux air valve & see what happens, also it might be the 5th injector not shutting down as the engine warms up, try pulling the plug on that too & see what effect it has.

 

I'll try those in a bit now the car is cold, and report back...

Thanks

 

No difference with the sensors unplugged still hunting at cold...

Going to try swapping over the WUR tomorrow... warm up reg... may be underfueling during low temps??

Last ideas

 

Where in the UK are you?

I've got a spare metering head/fuel distributor that you could try if you're anywhere near Bristol.

 

Thanks but about 230 miles away!

Fitten a new WUR but no change, but with regaurds the air control valves what function does each one have as i think im getting cross information.

1. The small solinoid block on the suspension turet is??? this clicks when the RMP drops.

2. The cylinder valve under the inlet im gussing this is the idel control or auxilary air valve? not sure if this is functioning.

 

1. The small solinoid block on the suspension turet is??? this clicks when the RMP drops.

Opens a little valve, allowing air to bypass the throttle plate and raise the revs, when revs drop below a threshold value (iirc 700rpm or thereabouts). When revs rise above 1200rpm (again iirc) it closes, allowing revs to drop back down.

2. The cylinder valve under the inlet im gussing this is the idel control or auxilary air valve? not sure if this is functioning.

This chap?:



is the auxilliary air valve yes. Closed when warm, open when cold. It has a heater inside to warm it up at the correct rate, engine heat as it warms up will also help it to close. Provides extra metered airflow to keep the engine running when it's cold (and oil is thick making it hard to turn the engine etc).

Should look roughly like this when cold:



Should look like this when warm:



There is a bit of adjustability in it, by loosening the little nut on a stud from the first picture, you can move the starting position of the internal plate a fraction. You need there to be no visible light through it when it's warmed up. Connect 12v to it, if you need to check it off the car.

 

^^^

Big thanks

Thats what i though they were... i have a funny feeling the Aux air valve isnt functioning for one reason or another, and the other valve only is controlling the revs at cold hence the hunting up and down between 600 and 1200.

Will clean and check the aux air valve tomorrow,

 

Can anyone confirm the wiring colours to the 5th injector and the Aux valve?

Possible wiring problem when i rewired the bay.

 

My K-Jet 8v had a simialr issue that could also lead to stalling. It turned out the idle bypass in the TB was gunged up with crap. So I unscrewed it and gave it a good dose of carb cleaner and its been fine ever scince. It was so gunged up the idle had droped to the stage the idle valve would have to open to keep it running, then when it clsed it would die again, hence the revs going up and down

 

Not sure on the colours, but the AAV should have 12v any time the ignition is on, whereas the cold start valve is controlled by the thermotime switch.