Throttle back on plus a cleaned IAC

I found a few minutes recently to reattach the throttle body. It was a pretty unceremonial act, and since I was pressed for time I didn’t get photos of it. Really the experience can be imagined by going back to the post where I took it off and looking at the photos is reverse order. The only difference you would notice is that I replaced the gross old gasket.

Tucked Away All Down There…

While working on the throttle I noticed the idle air controller valve (IAC) tucked down there. The IAC is a device that is in charge of maintaining an engine’s idle speed. It has a servo motor controlled valve inside that is opened and closed to varying degrees by the ECU using a pulse width modulated signal. This allows the airflow to bypass the throttle valve in order to maintain a steady idle. The action of the servo can become dirty and sticky over time, and since I had clear access to the IAC I figured I take it out and clean it. It sits inside a rubber collar that is attached to the engine with a couple of bolts.

Getting a photo of the actual valve with my phone was not easy. You can sort of see it in the above photo. In truth it wasn’t very dirty, but it did have a thin coating of gummy residue on the outside. I blasted both ports with carb cleaner and ran a rag inside to clear that off. Then I moved the valve back and forth manually to make sure it could move smoothly. I could have rigged up a servo control circuit to actually test it out, but that seemed a bit more effort than I had time or patience to handle right now so I’m trusting that the servo itself still works.

A Series of Tubes

Since I had removed the main air duct to clean the throttle, I cleaned it off and looked it over to make sure there were no holes in it that might lead to excess air coming into the system after the MAF sensor. There were no big holes, but I did find a teeny, tiny hole in one of the bellow ridges. I doubt this was causing me the problems I am experiencing, but I put a little dab of rubber cement on it and covered it with a small piece of electrical tape just to plug it up.

I began to reassemble all the air hoses between the throttle, the IAC, and the engine but got called away half way through the process. Total reassembly and the next attempt to start the engine will have to wait for the weekend.