Won't idle down
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Won't idle down
My '88 Econoline 302 starts great and idles down, but won't idle down after I have used the accelerator. The van is seldom used during the winter and I have had mouse problems. I have to take the van on a trip, so I am going to remove the air cleaner to get at the throttle body and check for mouse nests. What should I use for a cleaner/lube in this situation? Any particular place you would suspect the problem lies?
Lead Driver
Joined: Jul 2007
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From: Rhode Island
I would suspect a sticky throttle linkage, or a failing/sticking idle air control valve. The idle control valve will be a large aluminum cylindrical device with one electrical connector on the end somewhere near the throttle body. It is secured with two bolts. Often times they get gummed up when sitting.
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Removed air cleaner assy. Should idle work with it removed? I assumed so and checked throttle plate. Has three cables, one to accelerator, one to some type cannister behind left headlight, and a small one to a unit high on engine compartment on right side. All seemed working OK and just a bit of rust. Worked the throttle many times and still no idle down. There is a diode on the wire coming off the air bypass valve (same as "idle air valve"?). Do these diodes ever fail?
So I will remove the air bypass valve per your suggestion. What do you use to clean these valves?
So I will remove the air bypass valve per your suggestion. What do you use to clean these valves?
Lead Driver
Joined: Jul 2007
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From: Rhode Island
I don't recall ever seeing one burnt out. Most of the time the actuator just gets all gummed up and stops working reliably.
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Thanks. Thats what my local Ford guy said. He also said he knew no way of testing them, but that the motor should idle down when you disconnect the actuator. I ended up buying a whole new unit ($66) and will install and report back.
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Put in the new unit and thought it was fixed, but no go. Seems to idle OK when transmission engaged, but as soon as I put it in neutral the engine RPM goes way up again. Does that diode on the actuator ever go bad? Is there some type of neutral switch involved?
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Thanks. Throttle linkage returns sharply to the idle adjust screw, so it must be a vacuum leak. Where can I find a diagram of all the vacuum lines? Is that cannister behind the left headlight a vacuum source?
Lead Driver
Joined: Jul 2007
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From: Rhode Island
The vacuum source is the engine itself.
I can't help you with a vacuum routing diagram, or about any canister underhood as I am not very experienced with the E-Series. Usually the emissions sticker underhood will have a routing diagram. If it doesn't, a Haynes service manual from Autozone should.
I can't help you with a vacuum routing diagram, or about any canister underhood as I am not very experienced with the E-Series. Usually the emissions sticker underhood will have a routing diagram. If it doesn't, a Haynes service manual from Autozone should.
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OK thanks. Is the main vacuum source is somewhere on the throttle body?
Does anyone here know about the little diode in a boat-shaped holder just inches from the connector to the idle air valve? Do these diodes ever fail?
Does anyone here know about the little diode in a boat-shaped holder just inches from the connector to the idle air valve? Do these diodes ever fail?
Lead Driver
Joined: Jul 2007
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From: Rhode Island
Can you take a picture of what you're talking about? I'm not aware of any diode.
There will be multiple vacuum ports on the intake manifold. I do not know specifically where they will be. The routing diagram would show where ports are.
There will be multiple vacuum ports on the intake manifold. I do not know specifically where they will be. The routing diagram would show where ports are.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
No, the main vacuum tree is located on the intake manifold itself. The diode you are referring to has never gone bad in my experience.