Idle ECU

[jsloden]

I was working on this problem a few months ago and gave up. I'm not sure if the idle ecu is out or if there's something else going on. You have to keep your foot on the gas for the first couple of minutes until the car starts to warm up. If you do this the car runs fine. If you take your foot off the gas within the first couple of minutes though, the car will die. I can unplug both plugs from the idle ecu and the car runs exactly the same. The green wire going to the ecu has power when the key is on. I'm guessing this is the power wire. Can anyone tell me where it is grounded at? Also, does the idle ecu get an rpm reading from the rpm relay by chance because mine has been having problems lately.

Thanks

[Bitsyncmaster]

The idle ECU gets the RPM signal from the ignition ECU (that signal goes to the ignition coil, RPM relay and tach). The RPM relay does not affect the idle ECU.

One owner I know just had that same problem and it took a bunch us to get his car fixed. A lot of things were fixed so he may be able to list all the things that needed repair. I can PM you his name if you want to get in touch with him.

[David T]

Anything that is not correct can upset the idle. Vacuum leaks, dirty injectors, CPR, worn spark plugs, to name just a few things. It usually isn't just one specific thing but a culmination of a bunch of little things.

[jsloden]

The engine was gone through at DMCH back in August. It was brought to me in September. It ran fine for a few weeks. There were several things that were replaced. The idle control valve, cold start injector, and the frequency valve are all new. I know that the idle is supposed to go up to about two thousand rpm's when the control unit is unplugged. Mine doesn't do this, which leads me to believe there is a problem with it. The car actually runs fine with it completely unhooked once it starts to warm up.

[RobotMartian]

I had this very issue for years. Just lived with it waiting for it to warm up. Disconnecting the idle ECU did the same as yours. After a VoD job and replacing a handful of wear items (plugs, spark plug wires, etc) the problem persisted and actually got worse. I set the mixture with a Dwell meter (on Dave's suggestion) and that fixed it.

[Elvis]

Did you try the "Search" ?

probably explained a hundred times that the idle motor could be stuck and how to check it



or a loose connector

or a bad power stage in the ECU

[jsloden]

Okay, finally had some time to do some more testing today. The idle control valve does have power going to it. I pulled the tube off of it and looked at it through the hole. Had a friend turn the key to position 2. It never moved. I actually got a screwdriver and move it a little bit manually. Started the car up cold and it idled up around 900 and never died. Then of course, once it warmed up it idled around 750. I believe I've found my problem. The ICV is less than a year old from DMCH. Anyone know what kind of warranty if any they have on parts?

Thanks