Throttle Control Valve

[bpossel]

My 1971 280SL idles very low when in gear (600).  When I switch on the air-conditioning, the idle kicks back up again (800).  In the processing of checking this out, I noticed that my "throttle control valve" seems to "spin" freely on its bracket.  There is a 19mm nut close to the bracket itself and another nut up by the "idle stop" (which I belive adjusts the idle stop itself).

Does this valve need to be tighten down?  If so, how can this be done without adjusting the "idle stop"?

Thank you for your comments.
Bob

bpossel
1971 280SL
Automatic, Light Beige, Cognac

[George Davis]

Bob,

it sounds like the idle compensator is not activating when you put the car in gear.  It should come on and move the linkage to keep the idle up, same as it does when you switch on the a/c.  I don't know enough to say more than that, but others who know the automatics should be able to help.


George Davis
'69 280 SL Euro manual

[Tom]

If you wire the positive lead of the constant speed solenoid to the Neutral Safety Switch (as opposed to the A/C clutch), the solenoid will activate when the car is in gear.  Theoretically, your car should be tuned such that you don't need the solenoid to activate upon entering a gear, but these cars are old and need a little help...

Best,

Tom


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1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
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[bpossel]

Hi George,

Can you point me to the "idle compensator".  Can't locate this in the previous posts.  Also can locate in the Haynes manual.
Thanks!
Bob

quote:Originally posted by George Davis

Bob,

it sounds like the idle compensator is not activating when you put the car in gear.  It should come on and move the linkage to keep the idle up, same as it does when you switch on the a/c.  I don't know enough to say more than that, but others who know the automatics should be able to help.


George Davis
'69 280 SL Euro manual

bpossel
1971 280SL
Automatic, Light Beige, Cognac

[Tom]

Bpossel,

Don't mean to speak for George, but I am pretty sure that when he refers to the idle compensator, he is refering to the part that sits on a bracket over the intake manifold that has a plunger protruding toward the front of the car that pushes the linkage rod adjusting air flow to increase idle.  It is also called:

Constant Speed Solenoid
Anti-Stall Solenoid
Idle Increase Solenoid

Hope this helps

Tom


_____________________________________________

1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
_____________________________________________

[George Davis]

Exactly; thanks Tom!

George Davis
'69 280 SL Euro manual