Mercedes Non Start Woes

[Negative Creep]

Well that's just typical. Someone comes to look at the car and it breaks down for the first time since I've owned it.

 

I did have a sporadic problem where the idle would be rough and a slight misfire between 500 and 1000rpm after it began to get warm and stopped after about 10 minutes. It's been parked up for 2 weeks and fired first time , but just as the guy left it stalled. It restarted straight away then died as soon as I pressed the throttle. It was at this point I noticed smoke coming from the intake chamber of the injection system. Basically it turns over fine, almost fires, pops a few times and smokes out the throttle body. It's parked outside so I've given up for the night, but does anyone have any ideas? Perhaps something to do with the fact it's been tipping down and moisture has gotten into the fuel system somehow?

[Partridge]

Is it always parked outside or was this a one-off?

 

[Negative Creep]

Always parked outside, has been in the same spot for about 2 weeks

[Negative Creep]

Just tired it from cold and it fired first time. Had that slight judder between 500 and 1k though. Now I don't know whether to hope it was a one off, be totally honest or pay for a mobile mechanic since its SORN and has no insurance

[Barry Cade]

Dizzy cap and rotor, common issue with these.. replace or just dry, clean and loads of WD40.

[Angrydicky]

My dad's E220 had an annoying misfire, traced to knackered HT leads in the end.

[dollywobbler]

Another vote for dizzy cap. As I discovered on mine (something to bear in mind Chaseracer!) there should be a seal inside the cap. There wasn't one on my 300E. They also crack and wear out, but it is mainly damp that causes an issue, just like you experienced. It's the warmth that tends to make it misfire. Leave it until it's cold and it may well fire into life. 

 

The bad news is that replacements don't seem to be cheap, but worth pulling it off to have a look. Probably a lot easier on a four-pot but on mine there are three bolts, and the one underneath the cap was a right sod to access. Chaseracer can at least be happy that I fitted a new cap and rotor arm so he doesn't have to go there!

[Mr_Bo11ox]

I'D SAY ITS THE DIZZEE, THE LITTLE RASCAL

[srad34]

As above, dizzy first, plugs, leads etc, easily sorted even though its a faff.

[UmBongo]

There's nothing worse than a car wot won't start, Guv.

[Twiggy]

They all do that Sir........................

[Negative Creep]

Couldn't find a cap or rotor arm at any of the local factors so just gave the existing ones a clean and dose of WD40. Very easy to get to but no sign of any sealing ring which may be the cause. Started and ran to temperature fine then happily restarted, although there is still that low range misfire. I have someone coming to look at it today (who phoned to confirm this morning so hopefully isn't a timewaster), and although I mentioned the problem he still wants a look.