2001~2005 ModelYear ExST V6~4.0L~SOHC engines were equipped with an IdleAutoControlValve\IACV
shown below; it's in easy view+reach behind the ThrottleBody on the ManifoldThroat. The PCM computer
controls StartingRPM\Flare using this valve, depending on SetScrew position, & targets specific WarmUp
RPMs. A soft rubber Seal covers the SetScrew & may be removed with a razor knife for adjustments; use
RTV to make a new seal once adjustments are done. Occasional removal+cleaning of the IACV with spray
CarbCleaner & soft bristle brush is recommended; also inspect+lube the ORingFigure8, replace if needed.
The flange MountingBolts are 8mmHexHeads, the SetScrew is a 5mmAllenHead. Also listed below are my
SetScrew adjustments that lowered engine StartingFlare by roughly 500rpms; this was done in an effort
generally to minimize engine wear during ColdStarts , but specificly to reduce TimingChain Guide wear;
this should be done only when the engine is tuned up, running smoothly, without any MisFire or VacLeak.
IACValve VacuumLeak Test
With Engine Temp >180f & Idle >650rpm, park Tranny, engage ParkBrake, then unplug the IACValve 2Pin
Socket: if Idle falls to ~500rpms or Engine stalls, no VacLeak; if Idle holds, there's a VacLeak somewhere.
Links To Related Info
Thanks go to the brave souls who've preceded me in similar adventures & freely shared their experience:
- http://youtu.be/ayjhL9jpFH8?t=1 IACValve Diagnos
- http://youtu.be/bdVwQFgZatU?t=1 IACValve Cleaned
- https://web.archive.org/web/20210429114719if_/https://www.ranger-forums.com/how-diy-submissions-59/how-clean-iac-idle-air-control-valve-142103 IACValve Cleaned
- https://web.archive.org/web/20210429114240if_/https://www.explorerforum.com/forums/threads/shoc-remanufactured-engine-with-pre-oiler-timing-guide-reliability.473492/page-2 IACValve ColdStartRPMsFlare Setting