Hi there, I've got a 1990 190e 2.6 with the KE-Jetronic fuel injection system and a 5 speed manual transmission. Circa 120k miles.

A little background to my problem first. Occasionally, when I had stopped at some traffic lights after the engine had got to full working temperature, it would die if I put my foot on the gas too quickly. If I kept the revs above 1500 or so, it would drive fine, as though there was nothing wrong. The problem got gradually worse so that if I put my foot on the gas at all, it died. Sometimes it would restart almost straight away, more often than not, it needed ages before it would restart.

Anyway, I've tested all the sensors that I can, tested fuel pump and OVP relay - both appear fine (although I did go through and re-solder all the joints on them both anyway). Idle control valve has a good healthy pulse to it when cranking, pin 3 on the diagnostic socket checks out with 70% duty cycle (checked with an oscilloscope).

I left the car on my drive for a few days, now when I go to start it, it generally doesn't want to know, and when it does try to start, it makes an awful noise (like the exhaust is blowing, but it isn't...!) and tries to blow smoke out of the air intake (air filter is off).

One thing I've (stupidly) done is mess with the mixture screw (the one that you access by putting a 3mm allen key down through the air cleaner) and have no idea where it was set. How can I re-set the position of this screw?

What's my next step? What would make it try and blow gases out that way? It's been about 2k miles since I rebuilt the head with new valve stem seals. Is it likely to be a vacuum leak (can't find one so far), or something broken within the engine (although there's no funny noises).

I'm stuck, help!!!!

Cheers, Martin