I had an Idling problem that seems to have been caused by several different issues. In the troubleshooting I got it down to a few possible and I was not able to determine the actual cause. My 1997 TJ 2.5L was idling at ~2200 RPM. I finally decided it was the computer, but I was told that it was not the PCM. I tried changing the TPS 2 times and the IAC 2 times because of the forums talking about getting bad ones from the store, but there is no way to determine if they are good or not, especially if you aren't sure that is the issue. So after being told that it was not the computer by the PCM folks and sending it to the mechanic and being told they thought it was the PCM, and the Jeep dealer telling me it was too old for them to work on, I had to do something. I needed to determine the issue or at least rule things out. So I made an IAC tester. What is an IAC tester? Well, this one didn't exist before. it may never be useful again, but I wanted to save someone else the trouble I had. This device will plug into the IAC plug in the Wire harness and graph as well as record the the pulses the PCM sends to the IAC. It will also connect directly to the installed IAC and move the IAC valve. You can uninstall it and watch it move as well if that is your preference.
My preference was to be able to move the IAC while installed to cause the engine to idle high or low and then see what the PCM did in response, so connecting this device to the IAC and the PCM will allow you to do that. You are in control of the IAC and the PCM does what the PCM does, but the device records it and allows you to download the response log. I was able to determine it was neither the IAC or the Computer in my case and that it was a multitude of issues, but i was able to get it fixed. Only after I could prove to myself that the IAC was being controlled properly and the IAC was responding properly. I have no intention of keeping this thing for myself or producing them, so I have released the information on GitHub. I would call it open source Hardware and Software.
The tester has no buttons on it. It has a website so you control it from any device with a browser connected to the network it is on. it will connect to your Wi-fi or produce its own if it can't connect for some reason.
You can find details here https://github.com/dustywill/IAC-Tester
I hope this helps someone.
My preference was to be able to move the IAC while installed to cause the engine to idle high or low and then see what the PCM did in response, so connecting this device to the IAC and the PCM will allow you to do that. You are in control of the IAC and the PCM does what the PCM does, but the device records it and allows you to download the response log. I was able to determine it was neither the IAC or the Computer in my case and that it was a multitude of issues, but i was able to get it fixed. Only after I could prove to myself that the IAC was being controlled properly and the IAC was responding properly. I have no intention of keeping this thing for myself or producing them, so I have released the information on GitHub. I would call it open source Hardware and Software.
The tester has no buttons on it. It has a website so you control it from any device with a browser connected to the network it is on. it will connect to your Wi-fi or produce its own if it can't connect for some reason.
You can find details here https://github.com/dustywill/IAC-Tester
I hope this helps someone.
