New to malfunctioning Bosch KE-jetronic
 

I have a 1988 420 SEL that has a most unnerving problem when it's started cold. It has a horrible miss and will hardly run on its own without me giving it some gas. I changed out the plugs and found one that was fouled pretty bad. I suspect a leaky injector but would like the opinion of more experienced minds present on this wonderful forum.

When it's fully warmed up, it acts like it won't get out of it's own way until about 4500 RPM. I realize this small engine is somewhat "cammy" but I drove a friends 420 and it would chirp 2nd gear--felt far stronger than mine and had twice the miles.

Any suggestions??? Thanks in advance.

:confused: :confused: :confused:

I don't think a 'leaky injector' will have much affect on normal driving. Unlike solenoid injectors, yours only shut off during decel and with the engine off. I imagine the fouling is more likely from oil from worn valve guides and seals. Did the engine drive better with the new copper plugs, at least briefly?

Steve

Nope, no burning oil. The car has brand new heads, guides, and seals. The fouling is very sooty, not oily looking at all. Like I said, it goes away once it's warmed up and driven some but it still has an unstable idle and runs very "un-Mercedes" like.

The car came from an estate auction in Palm Beach, FL. I'm not too terribly versed in the ways of Mercedes dealer service but it looked obvious to me that the car had been serviced by the numbers. Is it bad that the timing chain may have let go sometime before I got it? The left side valve cover looks as if it had been repaired at some point which makes me think the chain/guides let go.

Thanks for your input, though.

I would go to a indy MB shop and have them plugged in to their code reader ,should show the problem. the The Euro 420 engine in my 500 SE is anything but slow my wife says it sounds like a jet airplane when I kick it down to pass, the 420 develops max horsepower at a higher rpm than the 117 V8's.........
William Rogers.........