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Discussion Starter #1
Just curious how many owners have replaced this part, which costs something like $ 800.
A perfect idle is nice to have, but not necessary if the car runs well. My car wants to idle around 1500 rpm,
and I have the idle control screw completely closed.
 

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Never needed to replace mine. Don't remember reading about anyone else replacing theirs (on this board, or Probetalk, or 626net). So I think it very rarely needs replaced. But remember lots of posts about cleaning the IAC, because they can gunk up. And maybe stick open??

My car idles at 1500 when the engine is cold, but then slowly drops to 700 as it warms up. That's normal.

Other causes: Throttle butterfly sticking part open? Vacuum leak? (I'm just guessing.)
 

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Discussion Starter #4
I have an automatic, and one thing I have noticed is the requested normal idle does not work well for an automatic.
Idle usually means when not in gear. Usually an automatic is left in gear at stoplights, etc. The recommended idle is
too low when the car sits in gear.
 

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Just curious how many owners have replaced this part, which costs something like $ 800.
A perfect idle is nice to have, but not necessary if the car runs well. My car wants to idle around 1500 rpm,
and I have the idle control screw completely closed.
Mine was leaking coolant and, like you, I didn't want to have to pay for a new part, so I chose to take mine apart and see if I could refurbish it. Be very careful taking it apart, as there are springs and little bits that like to jump out at you. I ended up losing a piece at first, but there are a few pictures around Google of what the internal bits look like.

Also, the gasket between the two halves of the valve doesn't seem to exist anymore.

That warning aside, I took mine apart, cleaned it up and refurbished the gasket as best I could (thorough cleaning and moisturized with 303) and then put the thinnest layer of gasket maker on it before I put it back together, and it seems to be working great now. No more idle problems, no more coolant leak.

Also, also, I had seen a TB/IAC combo on ebay for like $280, so it wasn't an $800 price tag if I failed, but I'm quite glad I didn't have to buy it.
 

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I changed mine several times over the years. I bought a new OEM IAC 15-20 years ago. It was really pricey back then too. Improved the idle but did not bring it down to the 750 the car idled at when new. Tried a couple different IACs and none of them returned the car to 750. Best I could get was 850-950.

I have a few spare IACs I grabbed when at the pick-n-pull. I don't daily my PGT anymore so I can live with a slightly high idle. 1500 though would drive me nuts.
 

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Discussion Starter #7
I haven't ever seen a discussion of a different idle for automatics and manuals. If you have an automatic, usually it is left in gear the whole time, even at stoplights. The 750 rpm idle is too low, as the load brings the rpm down, and the engine will struggle. I find I have to have the idle at 1200 rpm. Then when in gear at a stoplight, it will be idling at around 800 rpm.
It has always seemed to me for a long engine life, you don't want the engine to struggle anytime, but keep the inertia going all the time.
 
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