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I purchased the car about 3 month ago. It supposedly has 78,000 original miles. It sat without being ran for 2 years because the owner lost the key. I had another key ordered and got a new battery. The car started right up and ran very smoothly. I did the basic things like replace the plugs, wires, ditr. cap, rotor and air filter. The engine still seems to run very rich and idles eratically. Does anyone have any suggestions on how to adjust the fuel mixture or idle ?? It did idle fast at first but there were a few disconnected vacuum hoses. I hooked them up and now it idles to low and almost stalls.
 

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Bill,<p>I did the previous post on the fast idle. Here's some thoughts based on my research on idle in general. <p>These engines use the Bosch CIS system. Remove the air filter and there is a white plastic screw about the diameter of a fat pencil. Wait for the engine to warm up (175F or so). Turning the screw out should raise the RPM. The next thing to check is the timing. Should be 8 to 12 degrees BTDC. <p>The last resort is the mixture adjust. Everything I've read gives me the impression that you don't want to monkey with this unless all else fails. Right in front on the fuel distributor is a hole. May have a screw or plug in it. Takes a 3mm allen to adjust the mixture screw inside the mixture control unit. Try the mercedes mailing list, there are several posts on the procedure.<p>JV
 

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I had this problem with my '79 280 SEL. We remedied the problem by replacing the spark plugs with ngk plugs and borg warner cables. It appears the Bosch cables have major inductance problems (the wires actually glow on a cold dark night)causing erratic firing and eventually fouling of the plugs (bosch plugs seem to foul very easily). This has remedied everything from starting problems to engine noise through the sound system. I have also noticed these same conditions on a Jaguar XJ6 and VW GTI w/bosch cables and plugs as well.<p>-Phil<p>: I purchased the car about 3 month ago. It supposedly has 78,000 original miles. It sat without being ran for 2 years because the owner lost the key. I had another key ordered and got a new battery. The car started right up and ran very smoothly. I did the basic things like replace the plugs, wires, ditr. cap, rotor and air filter. The engine still seems to run very rich and idles eratically. Does anyone have any suggestions on how to adjust the fuel mixture or idle ?? It did idle fast at first but there were a few disconnected vacuum hoses. I hooked them up and now it idles to low and almost stalls. <p>
 
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