Clk 230 irratic tick over

[alano]

Am hoping someone can help me it's my clk 230 convertible 2002 model. Sometimes / more than often when stopping at a junction the car's tick over goes up and down forcing the car to lurch forward. Even in neutral the revs still up and down , on the rev counter it looks like between 500 and 1000. But !!!! I can turn ignition off then on it goes away ??????
This is becoming embaricing more and more.
No errors coming up on dash and it's not all the time. Sometimes it's like it's firing on 3 cylinders when pulling away. I just stop and restart the car.
Has anyone had this problem before ?

 

[Tinkerer]

Sounds like it could be a dodgy MAF as I had that effect when I bought a cheapo off of fleabay.

 

[Pendragon]

Take a look at a thread I started a little while back. I was having exactly the same problem as you. It may be of help and it may not but better than spending a fortune on bits when they MAY not be required.

http://www.mbclub.co.uk/forums/parts-maintenance/128573-slight-miss-w202-2000-c240.html

Keith

 

[alano]

I am thinking of going down the checking pipes rout. As I have fitted a new maf unit and plugs which when I start the car it becomes lumpy. There are no engine errors on reader but when I rev a little it clears but comes back. Is the engine a negative set up where if there was a damaged or cracked hose it would cause this ? Like bmws. I will start in ten mins going round all the hoses with engine ticking over then off one by one. Will keep you informed lol.

 

[alano]

Just on a note what hose was choked as I will start on that one ?

 

[Pendragon]

It was the not actually the breather pipes but the metal cover they fix onto. The pin hole that lets the air in to the pipe/s were blocked on both mine. As soon as I had thoroughly cleaned them out she ran fine.
Not sure about the negative bit though.

Keith

 

[RichAJ]

Don't rule out a coil pack either.. i had the same one my previous 208 230k.

 

[Pendragon]

I fitted brand new coil packs all round a few weeks back along with all new leads and plugs and 02 sensors.....diagnostic is showing nothing at all so sat here scratching my head wondering where I go next with it. Thing is its not like it all the time. I can turn it off and start it again and its fine.

Keith

 

[RichAJ]

surely its the MAS/MAF then? if its not then i really can't think what it could be given what you have done. :-/

 

[Pendragon]

Nope, MAF is fine.................I'm the same mind as you, can't think of anything else either !

Keith

 

[RichAJ]

you've done everything else that would be obvious too

 

[Pendragon]

Its doing my head in to the point that I am thinking of selling it even though I just paid £1350.00 to have a Romano LPG sequential system fitted !

Thing is it runs fine and mpg is not down either !


Keith

 

[RichAJ]

quite extreme .. I know what you mean though, when its not exactly how you want it you start having those thoughts don't you.

I cant remember if we tried anything else with my old one (never happened on current). its only coils, leads and mas that come up and the fact its not constant would assume either of the 3 too. grr

 

[RichAJ]

the fact it runs fine most the time would rule the mas out i guess actually. would be more constant if it was that..

were all thinking ignition/air but could it relate to something as far back down the chain as pre ignition? im note sure what.. maybe its how you open the door?! HAHA

 

[Pendragon]

It could be that I upgraded the horn to a VERY loud one lol

 

[RichAJ]

HAHA.. nah must be down to the colour of the car.. respray in bright yellow and pink and it will sort..promise!

 

[RichAJ]

on a serious note is there any noise or a whine from the engine.. i guess not sure as its not doing it all the time.. couldnt be something like a wearing bearing in the alternator?

 

[Pendragon]

No, its as quiet as a church mouse. Petrol & match spring to mind !

 

[RichAJ]

55K engine

 

[alano]

Well I could rule out rocker cover breather and plugs. Just had two error codes showing two separate miss fires but running ok now. Then drove about 35 miles and low and behold its feckin back. Turned of ignition and back on its gone. No faults on ecu and still does it when I got home. It's like the revs dip below 800 or so then it compensates and pops above 1000 back and forth which sucks. If you sit at a junction and the car lurches forward even when I have the breaks on. It's a bit scary reversing in a space also, this is as intermittent as it gets. Still no fault found not giving in because I actually still love the car. Any other ideas ?.