intermittent engine idle problem

[birder-uk]

Hi everyone.
I'm new to this forum, since buying a 240 CLK. Its an 03 model, and all running fine, except, sometimes when stopping at junctions or traffic lights, the engine idle will drop almost to the point of stalling, but will then pick up to normal within a couple of seconds. it only happens now and again, so any ideas please as to what could be causing this intermittent problem.

 

[Pendragon]

Hi, I had the same problem.
Don't spent a penny until you have had it on a diagnostics machine otherwise you may well end up spending money on parts that you do not need. Initially I had mine on a diagnostics machine (before I bought my own STAR system) and it came up with faults relating to injectors, coils etc'.............but it was none of these. They cleared the "faults" which may well have been old codes that had not previously been cleared.

Mercedes had it for 3 days and couldn't find out the problem either.

Unfortunately I spent over £600.00+ on parts and it still didn't cured mine but also my STAR diagnostics machine, which I bought soon after Mercedes had the car, showed no faults so I was no closer to solving the problem. It seems to be a common fault on lot of Mercedes.....the forum is full of threads from members with the same unsolved problem !

I eventually found that the oil breather pipes were clogged up and the breather pin holes on the metal plates that attach to the engine where the pipes attached to were blocked. I cleaned them and it eased the problem a lot but didn't cure it.
It wasn't until I had to go on a 250 mile round trip, mainly motorway, that I gave it a good blast and that seemed to sure it. I had only ever used it locally in heavy traffic around Cardiff and I reckon it needed a good long hard blast on the M/way
I also used a product that cleans the valves etc' which seemed to help but I could have saved myself hundreds of £'s had I of checked the pipes etc' first.
Not saying this is your problem but worth checking and good luck in solving your problem as I know just how ruddy annoying it can be.

Keith

 

[birder-uk]

Big thank you to you Keith.My car is still under warranty, so at least I can go back to the dealers armed
with this info. I might even do it myself, where abouts around the engine will I find these pipes ? And is
it fairly easy to do....

 

[Pendragon]

Not sure where they are situated on your model but should be easy to spot but I dare say another member will be able to direct you where to look and on mine it was a dead simple task.

Good luck with sorting it and let us know how you get on. Hopefully the dealer will be better than the one in Cardiff who were useless.


Keith

 

[Man18430]

Allo Friend
You could have a go at having the MAS (Mass Airflow Sensor) looked at, a faulty MAS will certainly give you sloppy rev's / tick-over.
All the best mate.

 

[birder-uk]

Thanks again Keith....
Bill.

 

[WG M-B]

Some good advice above. It is always best to get the car checked over on star first though. Your issues could be anything from the above to ignition leads/ plugs.

 

[BlackC55]

As has been said.

Fault codes may not appear but live data can be analysed to see possible discrepancies.

 

[birder-uk]

Thanks to all the above for your kind help. I'll get the breather pipes cleaned, once Ive found 'em, see how that goes, and if needed will check the other things you mentioned. The car drives perfectly, only on the odd ocasion does it play up. just a bit irritating. its my first Merc, and I love it.
cheers guys. Bill....