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  #1  
Old 05-18-2010, 05:23 PM
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1985 300D idles high when motor is hot?

When the car is cold and when it first start up, the motor idles aout 700 - 800 rpm. When it get warmed up the idles is almost 1000rpm and the motor vibrates a little more. What is could be the cause for this change. I do not see any problems with the power in the engine it always pulls, but the idles issue bothers me.
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Old 05-18-2010, 10:42 PM
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Best go through the archives. I thought the late 84 and 85s might have some idle control regulation incorporated. Their injection pumps are a little different I think. Just not sure though.
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Old 05-18-2010, 10:49 PM
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sounds like someone upped the idle to cover a problem with the motor.
I'd lower it and see what shakes. I'd bet the timing is off, and the chain is worn.
new motor mounts, and shocks are needed I bet.
along with an updated rack damper bolt.
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Old 05-18-2010, 11:18 PM
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how would i lower the rpm
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Old 05-19-2010, 08:20 AM
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look at the linkage on the IP. down between the IP and the block, there is a long screw pointing up, with a 14mm jam nut on it. you have to loosen the jam nut, then adjust the idle with the long screw, then tighten the jam nut... not an easy task with good tools...
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Old 05-19-2010, 09:18 AM
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^ Yeah, the screw is turned using a flat screw driver.
That 14mm socket is three inches long, I've found it needs to be that length. It's a 1/2 inch drive, I loosen it with a breaker bar, then remove the bar, and turn the screw ccw to lower the idle, while holding the socket. I then hold the screw driver still while I hand tighten the socket, then finally tighten it with the breaker bar.
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Old 05-19-2010, 09:42 AM
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Quote:
Originally Posted by barry123400 View Post
Best go through the archives. I thought the late 84 and 85s might have some idle control regulation incorporated. Their injection pumps are a little different I think. Just not sure though.
The only difference I am aware of is the rack sensor.
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