Hello, and thank you for choosing Just Answer to help you with your questions!
how is it idling now? What is it idling at?
low? high? surging?
its idleing about1800 rpms and I can't slow it down
Sounds like a vacuum leak to me
You need to check things closely for a vacuum leak
Any of the vacuum lines,
Remove the large tube from the air filter to the throttle body, and check to make sure the throttle body is moving fully and closing all the way
Sometimes they'll get caked up with carbon buildup and stick, just need to be cleaned out
There is an idle adjustment screw, but it's not going to drop it 1000rpm's
I have checked and double checked everything for vacuum leaks can't find any
IS this that happened suddenly? something that gradually got higher and higher? or did you just buy the truck
just got truck
how are you checking for these vacuum leaks?
and have you pulled the tube off the throttle body to make sure the throttle plate is actually closing all the way?
I have traced every vacuum line and conectors and yes the throttle plate is closing
Get some carb cleaner or starting fluid, something like that. Spray it all around all of the vacuum lines, intake gaskets, etc and see if the idle changes
Also inspect that big tube from airbox to throttle body, as well as all of those pplastic baffles in there closely
I've seen that intake tube tear on the bottom or back side where you can't see it
Also, does it make any difference if you unplug the throttle position sensor?
and have you checked timing?
it has anew throttle position sensor and it does not change if it is unpluged the timing is right on and the big tube is intact
How did you set the timing?
with a timing light
Did you jump the terminals in the diagnostic connector? If you turn the distributor, does the idle go down?
yes I jumped the terminals and I haven't tried to slow the idle down by changeing the timing
If you set the timing to 10 btdc at 1800 rpm, then it's certainly not gonna be right
I would start by trying to pull it back with the dist and see if the idle goes down. If the previous owner had removed the dist, there's a possibility it's a tooth off
And I'm assuming you adjusted the throttle position sensor correctly (with a meter and feeler gauges)?
yes I adjusted the tps according to the book
ok. If you are 100% certain there are no vacuum leaks or intake leaks (which I still wouldn't rule out, just because there are about 14,000 vacuum lines on the back of the intake side) then I would try and turn the dist back and see if the idle drops down
if so, you may want to make sure it is at TDC and reinstall the distributor. Make sure you line up all of the matchmarks on the dist before putting it back in, there are markings on the shaft, the dist, and the gear that need to be lined up
Also there is a valve on the bottom of the throttle body that is the "high idle" valve. Sometimes this will gunk up. If you remove the throttle body, you'll see the coolant hoses. These connect to the valve. IF it gunks up in there, or if that temp sensor goes bad, it can make the valve stick open in the "high idle" like when you start it from a cold start. Sometimes cleaning this out real well will help things considerably as well
Let me know what you find, or if you have any more questions :)