I have taken nearly all of the smog stuff off of my f-150 302 because I use it only on the farm. I rebuilt the engine and put a slight cam in it so it would still provide enough vacuum to operate the computer properly. My problem is that it idles at about 1500 rpm. It runs good other than the very fast idle speed. I have looked for a vacuum in every place I can think to look. Timing is set properly. Any ideas of what I can try next to get the idle down to where it should be?

 

What smog stuff have you removed and how did you do it?
What cam did you use?

 

Vacuum leaks are common to high Idle.
I suggest you try the smoke testing for leaks.
If you are using a spray, Starting Fluid works best.

Check to see that your Throttle Body Plates are all the way closed?
Do your throttle plates have holes in them or plugs in holes?

Are the 2 ports facing the driver’s side on the Throttle Body still connected to the Charcoal Canister or capped off?

Tape off the Throttle Body completely, check to see if it starts, if it does not, poke a hole the size of a small finishing nail in the tape on each side.

Take photos.

 

Do I reply here?

 

Yes you can.

 

I have sprayed starting fluid everywhere I can imagine that there could be a vacuum leak. No increase in RPM so I can't identify a leak. Throttle body plates are completely closed. In fact I put an extra strong spring on them just to make sure and no improvement. I will check to see if the 2 ports facing the drivers side are capped off, but I'm sure they are because I capped off everything I disconnected from the smog stuff. I am anxious to try your suggestion to tape off the throttle body and maybe poke holes to see if that makes a difference. I will try that tomorrow.

 

I removed everything I could see that was related to smog. I tried to get it back to a pre-smog 302 engine like I have in my older 302 engine trucks that didn't have any smog stuff on them. I don't exactly remember the specs on the cam I put in several years ago, but I do remember spending a lot of time on the phone with the Jeg's guy trying to determine how much cam I could go with without reducing the vacuum too much to mess up the computer stuff. The cam really wasn't that big. Just slightly more than stock.

 

Also when you get the chance, check the voltages @ the TPS connection.
Reference voltage, Signal voltage & Ground.