throtle solenoid
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throtle solenoid
I noticed that my throle solonoid stay on all of the time unless you unplug it. when you plug it back in it stays off until you tap the throtle and then it comes on and stays on. Is this normal? i thought it was just used to up the idle when the AC is on. oh yeah it is on a 77 F-150 400
thanks
David
thanks
David
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Joined: Feb 2000
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From: Brea CA
throtle solenoid
Oops, missed the second half of your question. It depends on the application, some were on all the time (anti-dieseling solenoid) and some were on only with the ac (bumps up the idle speed). Will have to look it up when I get home tonight unless someone chimes in sooner.
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throtle solenoid
Most engines in the late 70's early eighties where tuned for emissions. One way to reduce emissions is to retard the timing at idle. This requires the carb butterflies to be opened more to keep a decent idle speed. The increase in air flowing by the butterflies helps lean the idle mixture and reduce emissions. But it will also cause the engine to "run on" when you turn the key off (especially in the summertime). To keep this from happening, the factory added the solenoid on the carb so when the ignition is turned off, the solenoid drops back and fully closes the butterflies, preventing the run on problem.
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throtle solenoid
The way i noticed this was because my truck just started dieseling a few days ago. i posted a message here and was told that it can be caused from too high of an idle. I dont know the RPM from lack of a tac but the truck could idle at 15 MPH. when the solenoid is off the idle is much lower. Should i just adjust the position of the solenoid so that it dosent hold the idle so high or what? 
:-X11
Sorry, i dont know too much abot engines etc. but i am trying to learn
thanks
David
:-X11 Sorry, i dont know too much abot engines etc. but i am trying to learn
thanks
David
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Joined: Feb 2000
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From: Brea CA
throtle solenoid
I hear ‘ya franklin2 but I had a ’73 Maverick with a 302 and the anti-dieseling solenoid plus a ’79 Capri with a 5.0L and the solenoid for bumping up the idle speed for ac only, go figure.
David, assuming it’s an anti-dieseling solenoid, adjust the idle speed with it activated and pushing on the throttle. The whole unit is mounted on a bracket that can be adjusted back and forth for how much it pushes open the throttle. It basically IS the idle speed adjustment. When you shut off the engine, the solenoid is deactivated and lowers the throttle position so the engine is starved for air. Then the only thing holding the throttle open is the old-fashioned screw that you are used to seeing. That screw needs proper adjusting too, just back it off and then turn it in until it just contacts the throttle. This keeps the butterflies from sticking in the bores.
David, assuming it’s an anti-dieseling solenoid, adjust the idle speed with it activated and pushing on the throttle. The whole unit is mounted on a bracket that can be adjusted back and forth for how much it pushes open the throttle. It basically IS the idle speed adjustment. When you shut off the engine, the solenoid is deactivated and lowers the throttle position so the engine is starved for air. Then the only thing holding the throttle open is the old-fashioned screw that you are used to seeing. That screw needs proper adjusting too, just back it off and then turn it in until it just contacts the throttle. This keeps the butterflies from sticking in the bores.
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throtle solenoid
And what if its not for anti-dieseling? also, ifit is for anti-dieseling then what about when you turn on the A/C?
Just trying to fully understan this stuff.
thanks for all your help.
David
Just trying to fully understan this stuff.
thanks for all your help.
David
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Joined: Feb 2000
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From: Brea CA
throtle solenoid
David it is for anti-dieseling, looks like all '77s are (should have listened to franklin2). Go ahead and set it the way I said earlier. The engine idle speed with the solenoid ON is 650 rpm. It doesn't matter if you have AC or not. Now with the solenoid unplugged, the slow idle speed should be 500 rpm by adjusting the old-fashioned screw. It's probably close to where I said anyway.
Barry
Barry
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