Anti-Diesel Screw

[fixing_franklin]

So I've put myself in a pickle, when I first got the truck it had a very low idle, and like any guy who owns an old classic, I adjust the idle.....I'm sure most of you are going "come on!" But I got the truck to run alright for a little bit, but then I found out about the IAC, I replaced that, long story short, how do i get my anti-diesel screw in the correct position

 

[RonD]

After engine is fully warmed up let it idle and then unplug the 2 wire connector on IAC Valve, RPMs should drop to about 500-600, engine barely running, if so all is good no adjustment is needed

If they are higher turn screw counter clockwise, closing throttle plate a bit until RPMs are 500-600
If engine stalls turn it clockwise a bit and restart

This screw is also use to set TPS(throttle position sensor) voltage to .69-.99 when throttle is closed, but fine tuning only

Its not required but not a bad idea to unhook one battery cable for a few minutes and then hook it back up after adjusting a sensor like the TPS, which, in essence, you are doing, this will cause computer to relearn its setting
Idle may wander a bit for a few days while it relearns, thats normal

 

[fixing_franklin]

Hey RonD, I wanna thank you for helping me, i couldn't get my idle set just right, I've got a vacuum leak and I know where it is, but what it is is a different question, now my idle only get high when I turn on my ac and left off the gas, it will only lower when I come to a stop. I fixed the battery issue I was having by just replacing the alternator.

 

[RonD]

Idle should stay high until speedometer is below 5mph or when stopped, its an emissions thing, an idling engine(under 1,000rpm), is a big polluter, so computer opens IAC Valve to hold higher RPMs as long as practical.
With manual transmissions it also holds RPMs higher when shifting

Newer vehicles actually shut off engine when stopped and then restart when you press on gas pedal to go again, thats to meet the newer idle emissions restrictions

 

[fixing_franklin]

Idle should stay high until speedometer is below 5mph or when stopped, its an emissions thing, an idling engine(under 1,000rpm), is a big polluter, so computer opens IAC Valve to hold higher RPMs as long as practical.
With manual transmissions it also holds RPMs higher when shifting

Newer vehicles actually shut off engine when stopped and then restart when you press on gas pedal to go again, thats to meet the newer idle emissions restrictions

What if my idle doesn't drop as dramatically when unplugging the IAC

 

[fastpakr]

Then you've still got a vacuum leak or the screw is holding the throttle too far open.