Hello Folks,
I'm after some advice if possible.

I have just replaced the headgasket on my trusty W126 300sel. It runs very well, very quiet, however when at idle and in drive, it is rather lumpy, as if it's misfiring but isn't.

I have replaced....

Headgasket,
Exhaust, inlet gaskets,
All oil seals,
Spark Plugs,
Distributor Cap,
Rotor Arm.

I've checked the leads as well, they are fine.

Must admit, I'm a bit at a loss now, unless it's the idle control valve that needs clearing out, but it was fine before I took the engine apart. The engine and drive are fine other than this....

However, Could it be one of the multitude of vacuum pipes that I took off and have re connected . Stupidly I didn't take a note of where they went. Doh....

All help gratefully received folks,
Mike.

First of all, how do you know that it is not miss firing. Second the quickest and easiest thing to do is to try a bottle of Techron in the gas. You also had to remove your FI lines dirt could have gotten in there. As far as the vacume lines you will have to get a manual and see where they go.

John Roncallo

You've changed a lot about how the engine runs. My guess is the mix is wrong now. Check the ratio and EHA current at idle and 2500. The mix needs are probably different now that you've fixed a bunch of problems. Search on X11, X92, EHA, and idle mixture

Thanks folks, I'll try the injector flush.
with regard to it missing - I have replaced all of the electrical side, it's sparking on all 6.
It's only slightly lumpy at idle - perfect otherwise.

__________________
Mercedes Benz 300sel. 309,000 miles (What that is in km I don't know) - My workhorse, faultless mile eater that refuses to die.

TVR Chimaera...4.0V8 A whole bundle of tailsliding fun.

Volvo S80 - So sensible it's boring.

did you do a valve job when the head was off?

did you do a compression test before taking it all apart? if so what were the results?

a vac leak would more likely cause a high idle i would think, but my experience is more with carbed engines. you can of course run a vac test and see what you get. that should reveal any vac leaks. better do this before tweaking the mixture.

save adjustments of mixture for after all troubleshooting has been done.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

hi Tom,
No valve job or compression test, it was running very well prior to the new gasket going in.

Its much better now, and seems to improve the more I drive it.

__________________
Mercedes Benz 300sel. 309,000 miles (What that is in km I don't know) - My workhorse, faultless mile eater that refuses to die.

TVR Chimaera...4.0V8 A whole bundle of tailsliding fun.

Volvo S80 - So sensible it's boring.

That would make sense....

__________________
Mercedes Benz 300sel. 309,000 miles (What that is in km I don't know) - My workhorse, faultless mile eater that refuses to die.

TVR Chimaera...4.0V8 A whole bundle of tailsliding fun.

Volvo S80 - So sensible it's boring.