86 S10 2.8 idle problem

[sawsharp]

1986 S-10 4x4 2.8 can not get it to idle under about 1300 rpm. I have replaced the IAC, TPS, MAP, O2, injectors, reset the timing, checked the EGR operation, and reset (several times) the idle by seating the IAC with the diag. grounded and then reset the TPS to the correct voltage. After all of this it idles fine until you shut it off. The first time you restart it the ilde jumps right back up to 1300. It runs fine otherwise. Any ideas.

[Crasen]

Originally Posted by sawsharp

1986 S-10 4x4 2.8 can not get it to idle under about 1300 rpm. I have replaced the IAC, TPS, MAP, O2, injectors, reset the timing, checked the EGR operation, and reset (several times) the idle by seating the IAC with the diag. grounded and then reset the TPS to the correct voltage. After all of this it idles fine until you shut it off. The first time you restart it the ilde jumps right back up to 1300. It runs fine otherwise. Any ideas.

It sounds like you have a vacuum leak. Try spraying staring fluid around vacuum connection and around the intake manifold gaskets, if you hear a difference in the engine sound when you spray it at a particular location you have a vacuum leak there. If that doesn't work you probably need to adjust the minimum air rate setting. I do have

[sawsharp]

Originally Posted by Crasen

It sounds like you have a vacuum leak. Try spraying staring fluid around vacuum connection and around the intake manifold gaskets, if you hear a difference in the engine sound when you spray it at a particular location you have a vacuum leak there. If that doesn't work you probably need to adjust the minimum air rate setting. I do have

Thanks I to thought about vacuum leaks but have been unable to locate any. I am not familiar with the minimum air rate setting could you advise. Thanks

[Cam1959]

did you check the 2 vacuum lines running down over (sometimes too close too) exhaust pipe to top of tranny or transfer case ?

as well as one 2 diaphram and ball at fron right for front axle...

and lines in dash for vac diaphrams that redirect inside air flow ?