I have a 1993/4 S500, on two occasions after about 15 minutes of running, the engine starts to misfire.
Unless I can keep the revs up, which I have managed on other occurrences, the missing gets worse and eventually the engine will die.
Last night I had to call the AA out and after doing some tests the mechanic determined that the problem was overfuelling. When the engine was cranked, it backfired. He removed the fuse from the fuel pump and cranked the engine for about a minute then re-fitted the fuse and after a bit more cranking, the engine started. It stuttered for a few seconds and then worked as normal.
The car had been standing for about 5 weeks prior to this and although it started immediately the battery could have been a bit low in voltage.

It appears that the "choke" is not coming off or is coming back on again. (I know on fuel injection its not a choke, but can't think of a better word.)

Has anyone had a similar problem? I can't take it to a repairer, because the problem is not consistent. Are there any tests that I can do or does anyone have any advise.

Just on the side. The AA man couldn't get over the car. He just kept on saying what a marvellous car etc. And to put some of the sceptics comments into perspective he checked with other associates and they had never had a call out for an S500.

Help or advise would be much appreciated.

Regards
Piper
Kent
ENgland

 

One big question. When was the last time you tuned it up? Changed the plugs, checked the fuel pressure regulatior, knock sensor, 02 sensor. I mean...does your check engine light come on at all? Does your car have an idle speed regulator. Silenoids may need to be replaced...I don't know, but just a thought. What do you think?

 

Check for condensation in dist. caps. Pull them off and look inside, if there coated with a greenish powder , replace caps and rotors.