So, I’m not a car guy. I’m the guy who takes his cars to the dealership (not a garage!) and pays the service department to do whatever they recommend be done on the assumption that they know better than I do. All-in-all, I’ve probably shelled out thousands more than I should have over the years. That said, Melissa and I just laid out a lot of money for our upcoming move, so I was not looking forward to the bill I figured was coming when our 2002 Mazda Tribute wouldn’t start correctly this morning (nor, for that matter, the hassle of having it towed to the dealership).

The engine turned over (and the RPM needle moved up like a normal start), but then the RPMs dropped to zero and the Tribute stalled out. I started it again while giving it a bit of gas, and it would run as long as I feathered the gas pedal to hold the RPMs at the correct level, but as soon as I let off the gas it would stall out. I didn’t have time to mess around with it then because I was running late for church, so I moved my bass guitar to our 2006 Honda Civic and went about my business (trying not to think about the fact that the Tribute has already been in the shop twice for part failures since I got it eight months ago).

So I decided I’d try something new: attempt to diagnose and repair a car problem myself.

A quick search on Google revealed that this particular kind of ignition problem is often caused by a malfunctioning Idle Air Control (IAC) valve, which is apparently in charge of maintaining a correct air mixture when a car is idling. A malfunctioning IAC valve will cause the car to idle incorrectly (either too high or too low—even so low that it stalls out, as in my case) but will not prevent the car from working correctly when you give it gas. I found a number of people who reported the same problem with their early-2000s Tributes and Ford Escapes with roughly the mileage of ours, and they reported that replacing the IAC Valve solved the problem (and that replacing it was an easy job).

But I’m reluctant to lay out money for a new part unless I really need to, especially since the IAC valves run about $75 at each of the places I checked and my goal was to NOT spend much money unless absolutely necessary (though $75 is much better than $75+labor). So I kept researching, and some people reported that IAC valve problems are usually caused by carbon, dirt, and grime that builds up in the valve over the life of the car, and removing the carbon, dirt, and grime can solve the problem without requiring a new part. So I made a quick run to the nearest Advance Auto Parts, bought some throttle-body cleaner and some oil-absorbent paper towel things (total: less than $15) and got to work. I also picked up a battery-operated thermometer with an external sensor, since I’m spoiled by the thermometer in the Civic and wanted one in the Tribute ;-) but that’s neither here-nor-there.

I ratcheted off the two bolts holding the IAC valve in place, popped off the electrical connection, and inspected the part—which certainly seemed quite dirty. I cleaned it out as best as I could with the throttle body cleaner, left it to dry off for 20 or 30 minutes, then re-installed it in the car.

The moment of truth was upon me. I started the Tribute.

It worked, idling happily at the correct level :-).

Now we’ll see how long it lasts. But even if the part ends up going out on me in the near future (the cleaning is sometimes only a temporary fix) I know exactly how to replace it, and won’t have to pay the Mazda dealer to do it for me. It might not sound like a big deal to you, but this is for me!

Is this the beginning of a new trend? Am I going to go out and buy an automotive error-code reader and self-diagnose any future car problems? Will I learn how to change my own oil and filter or rotate my own tires?  . . . only time will tell ;-).