Rough idle returns with a twist code 412 | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Rough idle returns with a twist code 412


Well-Known Member
November 9, 2020
Reaction score
City, State
Greensboro north Carolina
Year, Model & Trim Level
1993 Ford explorer xlt
Hello all I have a 1993 ford explorer with a surging/hunting idle I decided to be smart this time and got a bosch 1300 scan tool that is cable of doing live data on ECC IV systems my problem is that when my truck is started cold it will idle at its regular 1500 RPM fast idle for about 20 seconds then it'll jump down to 800 rpms and jump back and forth from 800 to 1200 until it's warm and the truck will idle right I've checked for vaccum leaks with a smoke machine nun wer found I also have code 412 my iac percentage changes with RPM so would that mean my iac is at fault? Ect and everything else looks OK tps reads 1.0v I'd rather have it at 0.96 tho I guess I could change my injectors again with some better made bosch ones but I'd like to gets yalls opinions first on how when it surges the iac percentage changes, also unplugging the iac only makes it idle 50 rpms less with it plugged in once its warm it'll idle at 850 with it unplugged it'll idle at 800 wondering if my throttle body screw is set to high?

Have you cleaned the iac? Make sure to move the plunger inside while spraying the cleaner.
Yes it's spotless it's a new motor craft one would my iac percentage changing with a surge indicate a problem with the iac or wiring? I get 12.5 volts to the plug