Need help diagnosing bad idle

Kinja'd!!! "TheLOUDMUSIC- Put it in H!" (theloudmusic)
05/02/2016 at 17:29 • Filed to: help me oppo-wan kenobi, you're my only hope

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86 2.9 Ranger, won’t idle when hot. Idles fine when cold, but once it’s warm it needs very slight throttle input while running. My thoughts are IACV, because if I unplug that while cold it idles just like it does when it’s hot.

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F-Type burnouts for your time


DISCUSSION (10)


Kinja'd!!! crowmolly > TheLOUDMUSIC- Put it in H!
05/02/2016 at 17:33

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Yup, pull it and try cleaning it to start.


Kinja'd!!! PatBateman > TheLOUDMUSIC- Put it in H!
05/02/2016 at 17:34

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It sounds like you have a problem in the engine area.


Kinja'd!!! TheHondaBro > PatBateman
05/02/2016 at 17:58

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That’s what I was thinking. Probably has to do with the car. Could be the engine area, could be the rest of the car.


Kinja'd!!! PatBateman > TheHondaBro
05/02/2016 at 18:27

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Most likely, it's something either metal or plastic.


Kinja'd!!! Jayhawk Jake > TheLOUDMUSIC- Put it in H!
05/02/2016 at 18:37

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Problem: it’s 30 years old.

Solution: Buy new car


Kinja'd!!! Ike > TheLOUDMUSIC- Put it in H!
05/02/2016 at 19:07

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Throttle cable came slightly loose maybe? Try turning it a quarter turn tighter?


Kinja'd!!! DynamicWeight > TheLOUDMUSIC- Put it in H!
05/02/2016 at 19:39

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If you unplugged the IACV then the motor is always going to sputter right? That’s why it’s there. Sounds like you have a vacuum leak. But I’d do the normal things: plugs / wires / air filter / fuel filter / ignition / fuel pump / look for vacuum leaks / intake gasket / etc. etc. etc. Did ford ranger forums not show anything helpful?


Kinja'd!!! TheLOUDMUSIC- Put it in H! > DynamicWeight
05/02/2016 at 21:30

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Well, I cleaned it, and it idles WAAAAY better now, so that was at least part of the problem.


Kinja'd!!! TheLOUDMUSIC- Put it in H! > crowmolly
05/02/2016 at 21:30

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See reply to DynamicWeight


Kinja'd!!! gmporschenut also a fan of hondas > TheLOUDMUSIC- Put it in H!
05/03/2016 at 00:33

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when in doubt check vacuum lines. I kept having a weird thing on my 914 it would be hard to start, run rich and then run lean. I thought it was the Aux Air valve. anyway swapped the AAV and if semi fixed the problem before coming back. then it returned. I was double checking to make sure all hoses were on tight when I touched one random vacuum line and my idle instantly smoothed out. it was also one i had to undo to change the AAV, and again had loosened up over time.

lesson: if they are old, change your vacuum lines

and if new, get some hose clamps and snug them up