uneven CDI tickover

[automaniac]

I was wondering if any of you very clever chaps can offer advice on my year 2000, w210 220 cdi, apart from setting fire to it, that is...

when i start the engine the tickover is uneven, this lasts for about 30 seconds or untill i drive the car and it settles down. Usually worst when the car has a hot start. The car has been like it since i brought it a year ago but i lived with it and its now got worse, to the extent that it fluctuates so much it starts engaging the gearbox.
my local merc specialist could not find a fault, mainly because the diagnostic computer told him nothing!! What happened to knowlege of how things work, and what goes wrong?

Anyhow, has anyone had this problem with their car and what was the cure?
the car has 123k miles and is regularly seviced by the way.

any advice gratefully recieved

Thanks

 

[Dieselman]

The ECU performs injector balancing during the initial running phase. I suspect you have an imbalance in the injectors volumes.

Try a strong dose of injector cleaner, if that fails to fix it look for air leaks, otherwise you may have leaky injectors.

 

[automaniac]

Try a strong dose of injector cleaner, if that fails to fix it look for air leaks, otherwise you may have leaky injectors.

Thanks dieselman, would you get a smokey exhaust from leaking injectors?

 

[Dieselman]

Maybe, but not necessarily if it's only affecting idle due to there being such a low fuel delivery it's easy to have imbalance.

 

[BlackC55]

Normally on that engine missfires only point to injectors.

But, Is the glow system working properly? Have you got the afterglow?

(does your glow plug light extinguish after you start?)

 

[automaniac]

the glow plugs should be working ok, as they were replaced only last month. this fault was noticable by a really uneven initial tickover and the glow plug light staying on for 60 secs or thereabouts, longer than it should. (this problem according to the specialist's computer is now fixed) the real problem is when the engine is hot and when glowplugs are least needed that the worst fluxuations occur. I will try dieselmans suggestion of fuel additive first, as thats the cheapest solution, and see if it improves the situation