Piece of crap idle control valve
 

So I was kindly renovating the rubber pipes on my 190E, fitting nice new ones for it. However in the process I decided to clean out the idle control valve by removing and filling the inside with carb cleaner. Well what a mistake that turned out to be. Now the thing is jumping around all over the place, sometimes. 2000rpm, sometimes 700, frequently stalling. What a disaster.

So what can I do? Can I make this piece of rubbish work right (it was absolutely perfect before, I guess I shouldn't have messed with it) or does it need replacing? I tried some spray lube inside there in case I had dried it out with all that carb cleaner, but no luck.

I have also concluded the whole KE Jetronic setup is a giant compromise that should never have got past the drawing board. Suitable for a military vehicle perhaps but not a car. Rant over...

K-Jet is actually robust, and reliable. I've cleaned out a few ICVs with carb cleaner and never had one issue. Are you sure you got the rubber hose onto the head properly? It's really hard to get seated properly...if not...you would have a HUGE vacuum leak, stalling, etc. ;)

Did you orientate the ICV the correct way too?

Agreed. KEjet is a collosal POS. Check to make sure you idle activation switch is still aligned properly and being triggered when you close the throttle.

Cheers for replies.
In terms of vacuum leaks it seems okay, I have a vacuum tester which shows 15 - 17 in at idle depending on where you connect it. The economy gauge sits all the way left when at idle. I starts much more immediately since replacing the rubber pipework - even now when it is doing its bad idle. However I will double check vacuum just in case. I will bear in mind your comments that the IACV should not be damaged just by cleaning with carb cleaner and try to think of other culprits. Can I open the IACV up to look inside?

I still do suspect it's the IACV that's the problem though. My reasoning is because, if the idle is too high and I tap the IACV with something metal, then the idle comes down the more that I tap it. Which makes me think that it is sticking, somehow, and struggling to move smoothly on its own. That's why I hoped the lube would hell but I guess not.

I believe the direction should be so that air flows in the direction of the arrow embossed onto the IACV, yes?

Yes, the arrow should be pointed toward the intake manifold (direction of flow). Do you have a 2 or 3 wire ICV? The bosch ICVs are pretty universal to almost all euro cars from that era so you can use another one from pretty much any car.

I have a 2 wire IACV. However thanks for the tip about interchangeability, I didn't realise that would be the case since mine is a rare 2.5-16 190. I actually had a spare but I lent it to someone else to help fix his 190 and can't get it back!

I am still inclined to think that these IACV's can't be very complicated and it can't be hard (if you can open it up) to diagnose what is wrong with it. If only to learn what happened and why it broke to prevent others from doing the same. Anyone ever tried to dismantle?? Or anyone know a good way to test them? What happens if I apply a straight 12v to it from a spare battery I have?

It will just open and close.

If it does it sporadically like my old one it usually needs a clean. If you have already done this and it still misbehaves it might be just worn out.

They are listed here and are generally readily available so they must be something that needs replacing every now and then. Although the price makes my eyes hurt.

PeachParts FastLane Mercedes Parts Store

ICV
 

You are partially correct.
As a Mechanical Engineer, I can unequivocally state the the Bosch ICV in and of itself is not a POS. However, the entire K-Jet system as a whole IS a HUGE POS, Rube Goldberg, clap trap, overly complicated, WTF, fuel delivery system. If only someone made a replacement intake manifold for a carb they would be financially well off. Look at all the expensive, delicate crap (and weight) that could be eliminated from these cars. It is readily apparent that KISS is a totally alien concept to German (fuel delivery) Engineers.
Yes Virginia, the Emperor is naked.