OK, I admit it...I'm getting lazy - I appeal to all those that know K-Jet better than me to school me on the idle side of that crazy mechanical injection set-up. For review, 1981 242 GLT with B23E. The idle has always been a little rough (not the cam...really) but now the idle is inconsistent. Shouldn't it be more stable? The car will idle anywhere from 1000 to 500 rpm at the same settings.

I've replaced just about every item - hoses, plugs, wires, basic stage zero stuff. I haven't checked the injectors for flow rate or pattern (suppose this is the logical place to start) - but I'm wondering if there is some part of the idle control system that I'm overlooking. I've cleaned the TB, changed the idle control valve (air aux valve), changed the hoses etc. The engine was Sea Foamed last fall. My engine harness is disintegrating and I've got a new Volvo replacement to install. The connector for the CPR is broken, but it is connected and should work?

I've noticed the fuel pumps are making a fair bit of noise - I don't know what normal is - could this be the problem? How much buzzing is too much, or do you wait until you don't hear the buzzing?

Let the games begin.

You're saying that it idles, right? As in it doesn't die? It'll just sort of be 'odd' about what RPM it feels like idling at?

Could be a million things, but since it's 500-1000 and not 200 to 5000... I'd say you're doing all right

Now, you've changed the aux air valve, the idle majigger for kjetz - the wiring to that guy, have you checked it?


every kjet car i've owned, the fuel pumps have been loud as all balls. I can't guarantee that every kjet car I have owned didn't have dying fuel pumps though.


Good luck on finding the culprit, may I suggest switching to megasquirt? or a carburator?

Carbs...naw, one of the reasons I bought this car was to force myself to learn something about this new fangled fuel injection stuff. It will idle, I just never know at what RPM between the given range. Sometimes it's very low and almost dies and then other times it's higher and fine. If I get a chance this weekend I'll pull the aux air valve and ensure that it opens as it is suppose to - I've got to get the head ported and the new valves installed on this car before the snow flies (as well as get it painted), so if I can figure this out before all that happens it would be nice.

in my experience the aux air valve does almost nothing. you can check it in the morning to see how open it is, then let the car run and see if it closes off at all. I think their really only designed to work when the temps get below freezing. There isn't much of an "idle control" system on the non-turbo cars, so idle really comes down to spark and fuel pressure once you've got the airflow stabilized (idle screw set and no leaks).
So, monitoring fuel pressure is a step. dirty injectors will probably cause a rough idle, but should still flow consistently enough to maintain rpm.
I would check the intake boot under the manifold, and give the whole fuel distributor assembly a good cleaning, especially the flow plate. make sure it's set/positioned/moving as per the book too. the crankcase ventilation tends to allow oil to drip down from the throttle area onto the air flow plate which makes the car do funny things.

Craig, when you say it idles all over the place, are you talking about it surging from 500 to 1000 and back? Or that you'll be idling at 500 when you pull away from a light and at 1000 when you pull up to the next light? Or that in the morning it's at 500 and in the evening it's at 1000?

IAC valves on these cars get lazy - I'm convinced of this. At the very least, they've all had 30 years of operation, with a weak little clockspring trying to slide a plate that's being pulled against a seat by vacuum. They're going to wear. The heaters inside the mechanism fail and get weak too.

If your heater system is dead, or your wires are putting out intermittant current, the IAC valve is influenced by only two things: the temperature of the intake air, and heat transfer from the engine and compartment. Hot underhood air, hot engine, and not so much movement of the car will make the IAC valve try to close off, while lots of movement with the throttle lightly open will cool the IAC and make it want to open up.

These cars had another feature that has been disabled on your car: heated intake air. The warm intake air would minimize the amount of cooling the air brings to the IAC valve, and would help it close sooner and more completely.

In the winter, I've had the IAC valve try to stay open for my entire drive to work, but if I stopped for a coffee along the way, THAT'S when the idle would come back down to normal. Once it did, it would be fine until everything got cold again. At -35 or -40 and with a cold air intake, there isn't enough heat being picked up from the engine and from the heater to close the valve, until the car stops running and has a chance to heat soak.

Like Athal says, once it's closed, it's closed. It's SUPPOSED to be closed when everything's warmed up. If you've got inconsistant idle speed, it means it's partly opening for some reason. Check the heater operation, check the power to the heater from the fuel pump relay, and consider that without brand new parts and a heated intake, you may never get it right.

Also consider installing an idle control system from a 240 turbo. They've got a standalone electronics package, and though they use two other sensors in the block that you don't have, they operate just fine without them.

I only count one sensor on a turbo for the idle brain...the temp one, which as was said can be easily bypassed with very minimal effect. The other "sensor" on a turbo k-jet is the thermal cutout for the lambda brain. Having the electric idle stabilizer is real nice in comparison to the bi-metallic slide heater thing...


I haven't had a K-jet car that surges really...had lots of other things happen, but more violent idle surging or wandering not being one of them usually. I have had ones that lazy hot start from accumulators or injector issues or that have lazy idle slides that heat soak or don't heat soak that make for a fast idle or a slow idle depending on heat soakage.

The latter - which makes setting the idle difficult - when it starts it may be at 500 rpm, then at the next light 1000...then back to 750 continue quasi at random (and I say this as it is mechanical and therefore very unlikely to be random in its operation).



I've had a couple of them installed in the car - and I do have a brand spanking new one to try - given your explanation, this may not be the issue.





I'll so as Athal advised and check the rest when I get a second. I did have the issue with the fuel distributor boot, and since I've fixed that - I'm getting the idle weirdness (most likely not related). What are people's thoughts on the idle quality - it seems very rough and the engine is bouncing all of the place. My thought is that it seems like it is not running on all cylinders, but I don't know why that would be the case (ie I've got new plug wires, plugs, changed injector seals, replaced hoses etc).

Maybe I'll just forget it for now and worry about it when I get the head pulled and can change out the engine harness and work on cleaning and checking all the other little things.

By the way, about one more week to go on garage repair marathon then I will be flooding the board with new posts for bodywork on the 240 and 122...the latest addition to the tool arsenal are...



and

Injector seals been done recently? I don't think I did them. Crappy idle quality might be caused by leaky injector seals...

I likely have a ton of them with all the upper head gaskets sets I've used over the years...

I changed them as soon as I got the car. So it's unlikely the cause - though you never know.

if you haven't done them before they can be tricky to get in without twisting or warping. Especially the small ones on the outside of the injector holder.

yes...stupid design on those seals. Volvo makes their own vaseline stuff to help get the things in there. If there is any justification for that horrible plastic holder they gave us, it might be heat related. PITA to get those things in there without pinching them. I even buy OE volvo ones. In


Porsche has it right...k-jet injectors you just screw into the cylinder head with a crush washer....vac leak now you bitch! In crazy james land, I'd like to build a volvo with Porsche 924 injectors and weld the head and thread it.

Ok, looks like I've got to do them again...is it possible to get the injector cups locally or should I go to FCP for them? May as well replace them while I'm doing the seals.

Shouldn't be anything wrong with the cups unless you crack(ed) one extracting them to change the tiny o-ring. Did you do both seals? Shouldn't really need to do them again this soon. The first ones lasted 30+ years...

Some of the cups were in less than stellar condition up by the bolt. I didn't think it would matter at the time since they only see vac - maybe it does. I'm not opposed to doing this when I get the head pulled.

Well the idle roughness may indeed be coming from a misadjusted fuel distributor or a worn out control pressure regulator. Think Greg's blue car, and how much smoother it got when I richened it up a bunch. The idle INCONSISTENCY is probably another matter along the lines of your IAC valve, or a worn out throttle body perhaps.

You were having some running issues this past winter too, were you not? Might have been down to the fuel distributor as well. Have you wired up the WB02 sensor into the 122 yet? If so, next time you're up (or I'm down) we should do a tuning sesh.