will a bad IAC cause bad mpg? - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 08-05-2007
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will a bad IAC cause bad mpg?

i cleaned my IAC about a month ago and it was filthy with black crap. so i sprayed it all out with the MAF cleaner i have and re installed it and it made a howleing sound but it went away and just makes it quiet now at idle.

but after cleaning it i went from 14mpg- 21mpg and averaged for 3 weeks around 20mpg with 32.8 AT tires

no i'm getting 50miles per 1/2 tank will a bad IAC cause this to happen if its not working right?

need ot know if i should change it but the cheepest here is 90$
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Old 08-05-2007
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im not positive but i would think if its not working right it will effect your mpg
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Old 08-05-2007
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Based on the amount of Mileage loss you are stating, I would think the IAC is not the only issue. A bad IAC only showed a 1-3 mpg loss for me.
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Old 08-05-2007
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well i just bought a new IAC aftermarket and i sprayed down my MAF again so hopefuly it was something! has brand new plugs and 8mm wires 90$set synthetic oil, exhaust, cold air,

so ill see what happens now.
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Old 08-05-2007
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I believe the IAC (Idle Air Controller) is just a calibrated air by-pass control device (air bleed past the throttle plate) used to control the idle the same way as an idle stop screw works on a carbureted engine. The only difference is the computer controls it and constantly adjusts it to maintain a steady idle. Once you come off idle its out of the equation as far as gas mileage is concerned.
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Old 08-05-2007
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FWIW, the motorcraft wires are now 8mm. I just put a set on the explorer, right on the wire it says 8mm silicone.
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Old 08-05-2007
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The IAC on my ranger says in big letters, "Do Not Use any Solvents on the inside of the IAC" I'm not sure if it's just to get you to buy a new one, but maybe all your carb cleaner messed something up in there?
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Old 08-05-2007
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Quote:
Originally Posted by diocide
The IAC on my ranger says in big letters, "Do Not Use any Solvents on the inside of the IAC" I'm not sure if it's just to get you to buy a new one, but maybe all your carb cleaner messed something up in there?
well it fixed it for a month then it started acting up again. now thats its replaced the rpm's went from 1.2k to 900ish and no houling and truck isnt bogging as much. feels like more power off the line also pulling away from a stop sign

but i also cleaned the MAF so idk what helped the most i will check it out
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Old 08-06-2007
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check engine light on?
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Old 08-06-2007
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my IAC is shot, but I am still pulling good mpg numbers.

My tachometer reads 0 sometimes then jumps up to 700 and back down to 0.
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Old 08-06-2007
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I cleaned my IAC with Carburetor Cleaner at 60,000 miles and put an additional 70,000 miles on it with no problems. Some solvents will break down the rubber o-rings inside it, causing it to bind and wear prematurely. Making sure you blast it dry with compressed air will prevent any malfunctions after cleaning it, IMHO.
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Old 08-06-2007
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my ranger was meesing up and i took it to ford, they said it was the iac too. I asked how to clean or fix it and they said just to replace it and try to keep your air filter clean
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