Cold starting problem - W124 300CE

[grenachenoir]

My 1991 300CE starts absolutely fine, first "ping" of the key and no need for throttle when warm - or at least not stone cold. However, when starting in the morning or after it has been sat for a few hours it "churns" for a few seconds (not many, 4 or 5) and then bursts into life if I give the throttle a good push.

Any ideas as to why?

I have changed the plugs, filters etc - but not the HT leads or rotor arm yet. Anyway, I think the fact that it's fine when warm rules out ignition problems doesnt it?

I believe these cars have a cold start device that squirts fuel in when starting from cold - making use of throttle unecessary. Could this be the culprit? If so, where do I find it, how easy is it to investigate/change and is it expensive? Is there a fuse for it anywhere that may have gone?

Also, the idle seems slightly lumpy, not terrible but not absolutely rock steady either. It hovers around 500rpm which seems a bit low to me. How can I adjust? The "ever helpful" Haynes manual is utterly useless - it seems to me anyway - on either of these 2 points so I hope someone here can offer some advice.

Many thanks for any help!
Adam

 

[MangoMan]

See here: http://www.mbclub.co.uk/forums/showthread.php?t=37292

Ciao.

 

[grenachenoir]

Thanks Mangoman. Have changed the OVP relay fuse (it was blown when I got the car leading to very poor running) but that hasnt solved the cold start prob. Looking at the thread it does back up what I am thinking - just dont know where to look for the cold start injector.

Any ideas?

 

[MangoMan]

Sorry, I can't help you with that, haven't a clue.

I hope you get it sorted.......

Ciao.

 

[Dieselman]

It could be spark power but unlikely as it runs Ok once fired up.

A few things to check
Air leak into the inlet manifold will cause weak starting mixture, pull out the cold start injector and check it's spraying and also meter for 12v being applied to it.
Not sure about this but is the idle adjustable by adjusting the throttle flap or there may be an air bleed in the side of the throttle body. 500rpm sounds too low for a cold start, it should be nearer 1000rpm for that, then 600 when warm.
There must be some device to allow additional air when cold.

It sounds like it's just too slow as it starts when you press the accellerator.

 

[MangoMan]

Start Valve is number 32 in Dia.

Hope it helps.....

 

[grenachenoir]

Thanks Mangoman - I'll let you know how I get on.
Adam