W126 Lumpy idle and high vacuum gauge
 

Hi all.

Just recently my 560SEL has developed a lumpy old both cold and hot, slightly worse when cold.

I noticed this morning when the car was hot that the vacuum gauge at idle had the needle about half way between the far left stop and the beginning of the red marker.

Is this normal or indicative of a vacuum leak that is causing my high idle.

Cheers
Matt.

Matt,

Did this come one all of a sudden, maybe immediately after a start? I had a similar episode, rough start accompanied by a pop, rough and lumpy idle and the economy gauge was 1/2 way (or more) at idle.

Remove the air cleaner and look along the driver's side of the throttle body (RHD driver's side, passenger side for LHD). Look to see if a large vacuum line has come off the nipple. I posted about this a long time ago, I'll try and dig it up.

Hope it helps.

found my earlier post .