Chevrolet Repair: 93 Chev 454 in motorhome with Throttle body injection, chev 454, throttle body injection

Question
On start up idles at high idle for 4+ minutes before returning to idle RPM even at 75 degrees temp. I replaced the idle air valve on your recommendation (AC6 Standard). Plunger length is adjustable, so screwed out longer and longer with no better results. I am thinking there must be a sensor or sensors that drive the idle air valve. If I'm on the right track, where is it or they located? Could there be a problem with the computer. Haven't found the computer yet. Don't know what it looks like. Any ideas? Thanks a bunch. Bill

Answer
Hi Bill,
Normally I try to encourage people to test and clean existing parts. I hate to see people just replace parts without being certain the part is bad.
I for sure would be hesitant to replace the computer for that problem, because the computers used are very dependable, and just react to inputs from an assortment of sensors.
One sensor that could cause the high idle is the temp sensor. Now, even that is testable. Mitchell manuals have a chart on what the ohm reading should be at various temperatures.


Van