After a frustrating drive home last night, CEL/MIL appeared - no limp mode etc etc but idle was rough and dipping. No problem, reset ECU will deal with that .... great until tonight at which point it got to the point where it wouldn't idle at all and was sat shaking at around 300rpm.

Having done a bit of searching, it seemed IACV was the likely culprit especially bearing in mind that mine has never been great at tickover.

So 5 minutes with mini pliers and small spanner saw the IACV removed





As you can see, it's pretty skanky in there. I didn't have carb cleaner to hand so just used WD40 and an old toothbrush and several good squirts at close range.





Come up nice and clean and given what others have said about the motor / bearing, washing it in something like WD40 seemed a far better option than using carb cleaner. Been for a quick thrash, no CEL/MIL and idle is beautifuly stable at 800rpm, doesn't matter if i blip the throttle or let it fall from 3000rpm, it just returns smoothly to idle.

All in all, 10 minutes very well spent.

 

Time will tell

 

Yeah i'm just not convinced either MB but i am convinced there was a LOT of crap in there that will be much better off not being in there. Ordered one of those OBDII code readers today too, not going to play 2nd guess with a CEL but I saw no harm in checking the obvious - all in your excellent thread about idle problems

 

Mine went like that, cleaning it like you have gave me a few months more but in the end £60 for a used one from scrapyard fixed it

 

Just been back out for a further test - no matter what I do with the throttle, i cannot get it to stutter and stall. It's also stopped shuddering at low rpm as it bottoms out on the revs - looking at it, i'd say it has been like this for some time.

 

So where/what is that?

 

On the right side of the intake just behind the throttle cable adjuster. Big fat plug into it and two coolant pipes on it.

 

Clever little gizmo, and well worth a clean!

 

I don't fully understand the impact of this on anything other than idle - would it also affect urban mpg if you're in stop start traffic? I assume it gets gunked up and then can no longer move or restricts air flow through it?

 

It's just a throtle bypass, on old cars you needed to set idle speed by opening the throttle a little. This devise is a rotary throttle controlled by the ECU all it does is set the idle speed