high idle only once warm.

[watchamakalit]

In the last week or so I have developed a high idle after the truck is warm. Everything is ok when cold.  Once it starts to get even a little heat in the motor the idle settles in between about 1250 and 1500 and won't come down for nothing. Need suggestions. I'm pretty sure its a sensor issue somewhere.

[Pete M]

Could be heat expansion pulling the intake manifold from the head. Double check the torque on the bolts.

[MiNi Beast]

Tps

[watchamakalit]

Didnt think about heat cycling. Ive had intake bolt issues with this truck before so its very plausible.

 

Tps seems like it would be a constant problem even when cold. 

[cruiser54]

I wouldn't rule out the TPS. 

[watchamakalit]

Well I can rule out the intake bolts.  Just checked them and all tight.  I guess its on to testing the tps.....

[watchamakalit]

tps test values:

4.9V between terminals A/B

.7V between B/C with throttle closed.

 

Looks like it could use some adjustment but seems to be reading good when I sweep the throttle open it seems to be a nice smooth climb in voltage.  Doesn't seem to jump around or blank out.  Are the values far enough off I need to adjust it?  Might be my cheap @$$ dvom also....

[cruiser54]

Can't hurt. 

Tip 5 and 6 done? 

[watchamakalit]

1 hour ago, cruiser54 said:

Can't hurt. 

Tip 5 and 6 done? 

Yup. Did all that before I swapped this harness in. Am pretty sure ive fully cruserfied this truck except for a dizzy indexing.

[Pete M]

have you tried spraying a bit of carb cleaner around the intake manifold gasket?  even if the bolts are tight, it might still be leaking.

 

[watchamakalit]

I have not. I had kinda ruled out vacuum leaks with it idling good cold. Ill check it out....

[MiNi Beast]

Next be o2 sensor but i just throw parts at it without testing things first. 

[watchamakalit]

I'm gonna try not to go that route for a change.

[watchamakalit]

Update:  high idle has become constant, regardless of temp.

 

I found this issue today. Time to clean a TB......

 

 

[watchamakalit]

Upon close inspection you will notice I am wrong in my first diagnosis of a dirty TB. Look close at the cruise control cable and its orientation in the bracket. The servo cable is holding the throttle open. Unhooked it and ill is back to normal.

 

[MiNi Beast]

Good deal. Sometimes its just a matter of looking at things closer and understanding how things are suppose to work. Good job figuring it out. 

[cruiser54]

Excellent!!