92 s10 high idle

[jestersht]

hi i have a 92 s1o pu it runs great when i first start it but as soon as it warms up it revs upto about 1800 rpm, but if i unplug the vacuum sensor thats located beside the throttle body it will idle down to about 1100, i cant find any vacuum leaks and all vacuum hoses are in good shape but when it warms up and idles high if i touch the gas at all it will stall then i need to floor it to start it then it runs rough for a couple min then will idle about 1800rpm and run real rich itll stall if i put it in gear aswell when warm its a 4.3l tbi

its driving me nuts i cant figure this problem out so any help would be appreciated

[MT-2500]

Originally Posted by jestersht

hi i have a 92 s1o pu it runs great when i first start it but as soon as it warms up it revs upto about 1800 rpm, but if i unplug the vacuum sensor thats located beside the throttle body it will idle down to about 1100, i cant find any vacuum leaks and all vacuum hoses are in good shape but when it warms up and idles high if i touch the gas at all it will stall then i need to floor it to start it then it runs rough for a couple min then will idle about 1800rpm and run real rich itll stall if i put it in gear aswell when warm its a 4.3l tbi

its driving me nuts i cant figure this problem out so any help would be appreciated

What is the engine code NO?
What vacuum sensor?
One with a vauum hose on it or hooked into intake?
If you can post picture of it.

Any check engine lights or codes?
Clear codes and run and without unpluging anything.
Recheck for codes.
Post back code no.

The TBI on these have a problem on base gasket sucking air and carbon build up on inside by buttery flys.

Check and replace the TBI base gasket and clean TBI buterflys with carb cleaner and tooth brush.

[j cAT]

Originally Posted by jestersht

hi i have a 92 s1o pu it runs great when i first start it but as soon as it warms up it revs upto about 1800 rpm, but if i unplug the vacuum sensor thats located beside the throttle body it will idle down to about 1100, i cant find any vacuum leaks and all vacuum hoses are in good shape but when it warms up and idles high if i touch the gas at all it will stall then i need to floor it to start it then it runs rough for a couple min then will idle about 1800rpm and run real rich itll stall if i put it in gear aswell when warm its a 4.3l tbi

its driving me nuts i cant figure this problem out so any help would be appreciated

my guess the TBI has a fuel leak, diaphram is known to leak at this age.

[jestersht]

thanks im gonna change the tbi base gasket and see if that changes things before i change the iac, i havent had a chance to scan to see if there are codes on it but the light isnt on

[rprough]

How long does it stay at this high idle after starting it. Is it a cold engine problem only?

[jestersht]

itll stay at normal idle about 600rpm for about 5-10 min till it warms up then itll rev up to about 1600 and stay there, i think i narrowed it down to the egr vacuum solenoid