Rough idles and high revs

[theburger]

Hi all,

I have a 53 plate C180K and a few weeks ago the engine started to rough idle at tickover when warm. I have changed the plugs but it seems to be getting worse. The car runs fine in normal driving but when at standstill after 10-15 seconds it becomes rough. On my way home last night I put it in park a blipped the throttle a bit and the revs went to 1500 and stayed there. I had to put it in drive to drop the revs down. It does this every time now.

From what I have read it could be a breather or vacuum pipe.

Any ideas and what and where to check.

Thanks

 

[theburger]

I think I have found the problem

Just been doing some testing.

Hoping that I had an air leak I took a can of WD40 and sprayed it around the MAF intake area and the engine picked up for a second. This points to a leak. I then removed the spark plug cover and sprayed down where the vaccuum pipe goes down under the airbox and it picked up again.

So I guess that this points to an leak under the airbox. Will take it off tomorrow and check.

 

[Stratman]

A Jonah says:-

"WD40 sucked into the MAF may have contaminated it".

 

[BlackC55]

There is a breather pipe that splits under the air box. Remove it and take a look.

 

[theburger]

A Jonah says:-

"WD40 sucked into the MAF may have contaminated it".

Thanks for the reply and yes I agree it would do this......

The leak if after the MAF, that is why the car runs rough. If it was before MAF then there would be no problem as MAF would sense the extra air.