Hello...I just bought a 1979 450sel...it has a bosch cis injection system and the idle on this vehichle is running high at 1750 rpm...Also...the dual header pipes from manifold to muffler have some holes rotting through due to welds from brakets...I was wondering if anyone knows if the back pressur of the exhuast system will affect the idle speed ? I was also wondering if anyone knows about any links regarding the tin plate that is used to access history of vehicle service, spare key purchase, etc...I purchased this vehilce from a very well to do family in my small community....she was the only the owner and it was chauffer driven...it currently has 68,000 original miles and is excellent shape but just needs some TLC due to age and lack of use....I will post a picture of the beautiful vehicle once I get it polished. I hope my first message wasn't too long and that everyone here is patient with new owners with many questions...I have only just begun working on this vehicle and the sheer quality of materials and enginuity that went into this manufacture of this vehicle is nothing short of art and brilliance merged into one. Thanks again for your indulgence and I promiss to keep future posts shorter.

Respecfully,,,The Handy Man

 

[size=2]welcome.

as far as i know the back pressure have little or no effect on gasoline engine. on diesel engine, yes. F1 cars got no mufflers but it's quite fast

high idle speed?
was there a black smoke on your pipe... i mean the exhaust pipe?

on the upper front part of that fuel distributor, there is a tube -like that has a sealed plug. knock off that plug and using a 4mm allen key, adjust the idle speed to the proper rpm. but before you do that...
*check for any air leak. air leak causes high rpm. you can use water (it's safe) spray around injector area and inside where the intake manifold meets the throttle body. that seal always gets leaky. you can use carb cleaner too. any changes in rpm indicates the leak point.
behind the engine near the firewall is also a frequent leaky pipe. this pipe connects to the brake booster.[/size]