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Question by shadfurman: what is the black plastic screw on the bottom of the throttle body of my ’86 volvo 240 dl?
I have an ’86 volvo 240 dl (B230F engine w/LH 2.2 injection) there is a black adjuster screw on the bottom of the throttle body, what does that do?

Best answer:

Answer by David S
It is part of the idle speed control. On the fender above the battery you will find a plug with two wires that is not plugged into anything. If you ground one of the wires,I don’t remember which one, the idle speed will drop to it’s base setting. While idling at the base setting,turning the knob will allow you to raise or lower the base setting. Usually you set the base idle to where the motor is idling around 650-700 rpm. Un- grounding the connector should cause the idle to rise momentarily and then settle down to around 750 -850 rpm.

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