W126 5.6 high idle?.

[widebodysec]

Hi guys recently the car has started as normal then the idle once bit warmer stays about 800 850 rpm. It there a mechanical turn down or is this electrical?
Cheers again.

 

[television]

What year is the car please

 

[widebodysec]

1988

Hi fella we met at bbq 3 years ago. Silver wide body amg!
Car is 1988 5.6

 

[television]

OK I know who you are now.

OK there is 2 parts to your system. the car when at idle runs from the idle ECU, if there is a fault on the throttle switch or idle ECU then it reverts to the main ECU and high fail safe idle, do check the change over switch on the throttle.

Its easy to check if running on the idle or main computer ECU. if the speed goes up by 50 rpm when you engage D or turn the air con on, then working on the idle ECU if no change its running on the main computer ECU

 

[widebodysec]

Ok will investigate when get time and let you know my findings, thank you.

 

[ianrandom]

Worth cleaning your idle control valve by soaking it for a week in petrol or brake fluid. A simple and very cheap 'worth a go' thing.
They get full of carbon.