I have a 1988 F250 with a EFI 460. The top end was recently rebuilt with a rv cam. Currently it idles 1750-2000 rpm's cold and wont come down when it warms up. I am thinking the reason my truck is idling so high is because of all the vaccume lines that are unhooked. I need a good vaccume diagram so Ican replace all of the lines. Also, the coolant temp sensor is disconnected because the dash gauge is not reading. I also wanted to know where the coolant temp sensor is so i can hook it back up.

Thanks,
Matt

 

Oh.. that could be a problem.

Well yeah, so plug them back in. It doesn't matter where you plug them in either as long as the lines fit, vacuum is vacuum.

Dash gauge has it's own sensor.. a single wire thing right behind the #5 injector, the engine coolant temp sensor is a 2-wire in the thermostat housing.

 

The "sensor" for the ECM has two wires. The "sender" for the gauge has one wire.

 

I called the local ford service department earlier, they said to disconnect the idle controller solinoid thing below the intake openings on the throttle body. Would this work? And also would this throw a code?

Thanks,
Matt

 

Band-aid fix at best. There is a reason why there is an IAC in the first place. Fix the root cause, then move on. I highly suggest you never call that Ford service place ever again. Bad advice IMHO.

 

i also had this problem and was told it was map sensor replaced it and fixed the problem but mine kinda would idle right the all of a sudden climb and stay around 1900

 

you may have too radical of a RV cam for these engines !

 

Fix the vacuum lines first. Having open vacuum lines is equivalent to cracking the throttle open. It doesn't take much air to get an engine to idle at 1800 rpm.

 

I know the cam is fine, when I put it in gear, it goes down to 900, but it runs fine. I am going to fix the vacume leak, and see where it takes me.