K-Jet idle adjustment question

[AllHailKingVolvo]

Hi all,
My wife’s new ‘88 NA 740 (B200E) is an absolute peach of a car. The engine is smooth and peppy, and runs like a sewing machine. The quietest redblock I’ve come across, clearly a car which has had an easy life and maintenance intervals met.

I’ve tidied up a few bits that needed doing (drive/PAS belts, epic level coolant flush to rid it of the nasty OAT rubbish that was in it for some reason, new thermostat as it wasn’t getting up to temp etc) and now it is super smooth, reaches running temp quickly and all works as it should in terms of heating and cooling.

The only thing I haven’t been able to sort out is a bit of an idling oddity. Starting from cold, it fires up as it should and sits at around 1000rpm for a minute or so, then drops down to around 800rpm for the second stage of the warm-up cycle.

So far so good…the curious thing is, however, that after a run, when the car is up to temp, it then idles unusually high again, at around 1200rpm!

I’ve noticed that there is a microswitch behind the throttle lever (similarly to my LH2.4 cars) but that the throttle lever is adjusted so as not to touch said switch at any point in its travel. When the car is up to temp and I toggle that switch manually, the idle drops down to where I’d expect it to be when hot, around 700rpm. Release it, and it goes straight back up to 1200.

Is this a similar setup to the IACV trigger on the LH2.4 system? This is the first K-Jet car I’ve owned so am learning as I go. My suspicion is that it’s been adjusted in the past by a mechanic who doesn’t understand the system, but this is coming from me, a (very much amateur!) mechanic who doesn’t understand the system…

Any advice would be very gratefully received!

Ta,
Phil

[Steve 940]

Hi Phil,

Think I saw some mention of idling on a thread about Saving Kilorans 940 on here.

Pretty certain Luke (360 Beast) was replacing an engine for Kiloran, plus a myriad of other stuff, and recall some posts from either Luke or Dave (Laird Scooby) mentioning exactly about mechanics adjusting the idle incorrectly.

Might be worth a look at the thread, sorry I haven't yet fathomed how to copy and paste on here yet?

Cheers
Steve

[Steve 940]

Phil, see page 6 on Saving Kilorans 940
Cheers
Steve

[Laird Scooby]

Originally Posted by AllHailKingVolvo

So far so good…the curious thing is, however, that after a run, when the car is up to temp, it then idles unusually high again, at around 1200rpm!

I’ve noticed that there is a microswitch behind the throttle lever (similarly to my LH2.4 cars) but that the throttle lever is adjusted so as not to touch said switch at any point in its travel. When the car is up to temp and I toggle that switch manually, the idle drops down to where I’d expect it to be when hot, around 700rpm. Release it, and it goes straight back up to 1200.

Is this a similar setup to the IACV trigger on the LH2.4 system? This is the first K-Jet car I’ve owned so am learning as I go. My suspicion is that it’s been adjusted in the past by a mechanic who doesn’t understand the system, but this is coming from me, a (very much amateur!) mechanic who doesn’t understand the system…

Any advice would be very gratefully received!

Ta,
Phil

You've hit the nail on the head Phil! First you need to adjust the throttle butterfly so the idle microswitch is made. There should also be a knurled head plastic screw with an insert hole for a large (8 or 10mm) Allen key, wind this all the way in, counting the turns until it stops. Now wind it all the way out and remove it. Clean the pointed end with carb cleaner and also the holes it screws into - one hole is obvious, the other is deeper inside.

Now refit the air idle bypass screw (as it's called) and screw it all the way in. Start the car and make sure the idle microswitch is activated so it's idling at its slowest. Adjust the throttle butterfly to get it to 600rpm, making sure that if the idle switch disconnects while you do this that you adjust the TPS position to keep the idle microswitch made.
Once complete and it's idling at 600rpm, lock the locknut on the throttle butterfly screw and preferably put some quick drying paint on the threads of the screw and over the nut (TippEx, nail varnish and similar all work too) to prevent accidental movement and provide an indication if it has been touched by someone who shouldn't touch it, lock the screws that secure the TPS and then with it still idling at 600rpm, slowly undo the idle bypass screw until it idles happily at 700rpm.
I'm sure you've done the PCV system already but double-check the small bore vacuum stub on the inlet manifold is clear.

Job done!

Originally Posted by Steve 940

Phil, see page 6 on Saving Kilorans 940
Cheers
Steve

Close but no cigar Steve - Phils is K-Jetronic and Alans (Kiloran) is LH-Jetronic 2.4 - translation, K-Jet is purely mechanical and LH is fully electronic. Although the setting up procedure is similar it's slightly different as the K-Jet doesn't have an Air Idle Control Valve and likewise the LH2.4 usually doesn't have the Air Idle Bypass Screw. The procedures are very slightly different as a result and also because of a couple of other things too.

[AllHailKingVolvo]

Amazing, thankyou Dave!! Stellar advice as always. Will get onto this asap!