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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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2,280 Posts
Discussion Starter #1 (Edited)
My dad has an '80 450SL that idles high when cold and low when warm. Additionally, the car gets poor fuel economy.

One of the precatylitic converters was plugged so he had it removed (the other side is still there) and the O2 sensor was replaced. He's also replaced the injectors.

A local mechanic stated the mixture was leaned out "as much as he dares" but the car still runs poorly.

I'm a 108 guy by love and training so I have nothing to offer him. Any advice would be welcomed!
 

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1980 450SL, 1980 380SE
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9 Posts
I have the same car. It has the CIS injection which they had used since 76, but in 80 they added the 02 sensor and lambda control system. It adjusts the control pressure by rapidly cycling the frequency valve. The valve sits under the air cleaner just forward of the fuel distributor. It has a 2-prong plug and two small pipes going in/out. Don't confuse it with the cold-start injector, on the left cylinder bank.

With the engine running you should hear the valve buzzing. At first mine didn't work, and I could never make the engine run right. It was always rich and lacked power. I fixed it by replacing the overload protection relay. Inside the relay is a fuse, which had blown. The bad part was I had to buy the $35 relay just to replace the fuse since it's built in.
 

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1980 450SL, 1980 380SE
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9 Posts
I'm probably the age of the grandchildren of whoever bought my car. The name is part truth and part just because I like it.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,524 Posts
Sloane Rangers was a name given to well off and socially active girls in the late 60's who lived in Sloane Square in London, or was it Sloane St- hell, I can't remember, I'm not a Londoner.
 
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