I am having a fast idle problem with my 2.5L 4 cyl., in my 86 S10. Is there a way to adjust the throttle body for idle, like a carb?

With the air cleaner lid open, the fuel is constantly being sprayed in to the throttle body as it idles and I am wondering how to control this?

I have not worked on these throttle body systems.

Thanks,

Diehard
86 S20 2.5L
5 spd

 

i'd check for vacuum leaks, clean egr and idle air control valves. throttle body can't really be adjusted like a carb. there is something else going on.

 

I failed to mention in my first post that I am not getting a Check Engine Light that stays on. It sometimes with come if I am idling for a while but disappears when I start driving. There are no codes set in the computer that I can find.

I have checked for a vacuum leak around the throttle body and replaced on hose that seemed loose but could not find a leak. I sprayed WD40 around the throttle body while it was running but there was no change in RPM.
I have not checked out the EGR valve yet but I did switch out my MAP sensor with another used sensor and saw no change.
Is the static position of the EGR valve Open or Closed? I am guessing it would be closed.


Thanks,

Diehard
86 S20 2.5L
5 spd

 

there should be a screw with spring that you can turn that should adjust the near or on the throttle body

 

Unfortunately WD-40 Isn't volatile enough to be used as an air leak detector. I would use brake clean or starter fluid both are alcohol/ether based and are more volatile and will cause a rpm jump if sprayed on a vacuum leak.

 

I was having the same problem with my 93 s10 with a 2.8L and I took off the throttle body and drilled out the factory cap sealing the Idle screw. I re-adjusted the idle down to where the screw was not touching the linkage and it took it down to about 1000 rpms at idle but it still idles high at start up and stays up until the engine gets warm enough. I am going to try replacing the injectors because I noticed a drip from the injector on the passenger side and I think that it may be putting too much fuel into the intake causing the idle to be fast. Will post to your question after I swap injectors and let you know if this worked. Hopefully this will solve my problem as well as yours. When you drill out the cap start with a small bit and work your way up because the cap is made of some hard steel unless yours is the flat style and not the pointed type like mine.

 

I thank you for your advice. I have not cured the problem yet but have helped the driveability of it. This has been setting for a little while now as I have been busy with other items.

One thing that helped a little was resetting the timing to factory specks. It was high. This brought into play another problem with acceleration in 4th and 5th gear.
The Throttle Body does not seem to have a vacumn leak as I used carb cleaner around it to see if I could get an increase in RPM.

I will return with more information later.

Thanks Again.