Low RPMs

Nickc32

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Advocate I

Nov 3, 2020
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Nick
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Cirino
Hey everyone, I just got a 86 bronco and it has 100k miles. I start it up and only sometimes. It starts up. Rpms go up. Then go down to around 3-4 k. It sounds like it is going to then off. However does not. Any ideas??
 
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Jakob1972

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Aug 17, 2020
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1030 Park Rd 31, Spring Branch, TX, USA
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Steven
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Jakob
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Hey everyone, I just got a 86 bronco and it has 100k miles. I start it up and only sometimes. It starts up. Rpms go up. Then go down to around 3-4 k. It sounds like it is going to then off. However does not. Any ideas??
Hmmm I had an 84 that had a carburetor that would do the same thing until I put a predator on it. Is the 86 EFI?
 
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The Bronze

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May 20, 2020
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Kelly
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Shaw
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I couldn’t follow your post. Low RPMs, sometimes it starts? Sometimes it goes to high rpms and then lowers to 3000 to 4000 RPMs? Then offs?
Maybe you mean sometimes when you start it, the engine go up to a higher rpm, and then will drop to a low engine speed like 300-400 RPMs and sometimes sounds like it is going to die, but continues to run? 86 had fuel injection, I would look at the idle control valve which likely could be malfunctioning. It’s an easy component to change out. You can even just tap on it when it is idling low and see if the RPMs climb. If it does, it’s hanging up. You can try to clean it, but usually requires replacement.
 
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