Engine idle problems

chevrolet
s-10

#1


My S-10 is a 96 V-6 5 speed 110,000 mi.Starting the truck the idle is normal, But when you drive it the idle increases to about 1800 rpm.It will not go back to normal until you come to a complete stop. As soon as you start up and drive , again the idle goes up. I changed the IAC switch,and the TPS, no change. I then had the computer re-flashed, no change.I got a re-built computer , had it flashed, no change. I read that GM had a service notice and called it engine run-up. I disconnected the IAC switch. This keeps the idle down, but the check engine light comes on. Please help ! Thanks, Gordie


#2

If you read a service notice from GM on this, what do they say to repair the problem?


#3

I read online that there was a problem. I did not see it, nor was I able to find it. A GM tech told me he couldn’t find it, possibly because it was old and taken out of the system.
Thanks


#4

You may be able to search for technical service bulletins yourself at a local library. Some maintain subscriptions that allow you to do that.

Did you clean the throttle body when you replaced the IAC?

Does that transmission have any vacuum controls on it?


#5

Thanks for the reply. I’ll get to the library and see if any info is there. I did not clean it when I put the new iac in, but I did when the intake gaskets were changed. I’ll get it off today and clean it.Good idea. I don’t think there are any , but I’ll check that today also. I’ll let you know tonight.


#6

OK I took off the throttle body, cleaned it . No difference. There are no vaccume lines to the trans. I took the truck up to 40 mph, then depressed the clutch. The idle was at 2000 rpm. I then shifted to neutral and coasted to a stop. The idle stayed at 2000 until I was at about 2 mph. It then went down to normal. I disconected the cruise cable.to the throttle body, no change. I did the same with the speed sensor and the speedo, no change.


#7

HI
Just a note to say I found out what the problem was with the high idle. I had the throttle body off the car and cleaned it in laquer thinner. Bad move. It sure looked like there was nothing to harm in the body. Wrong. I went to the local bone yard and picked up a grungy unit and put it on the car without touching it. The truck now idles perfect. Thanks for the input Gordie