2001~2005 ModelYear ExST V6~4.0L~SOHC stock engines were equipped with an IdleAutoControlValve\IACV
shown below; it's in easy view+reach behind the Throttle atop the ManifoldThroat. The ECM\ECU\PCM computer
controls StartingFlare RPMs via this valve, depending on valve SetScrew adjustment, & targets specific WarmUp
RPMs. The soft rubber FactorySeal over the SetScrew may be removed with a razor knife for adjustments; RTV
may be used to make a new seal once adjustments are done. Periodic removal+cleaning of the IACV with spray
CarbCleaner & a soft bristle brush is recommended; also inspect+lube the Figure8 ORing & replace as needed.
The flange MountingBolts are 8mmHexHeads & the SetScrew is a 5mmAllenHead. Also listed below are my IACV
SetScrew adjustments which lowered engine StartingFlare by approximately 500rpms; this was done in an effort
generally to minimize engine wear during ColdStarts & specificly to reduce TimingChain+Guide component wear;
this should be done only if an engine is otherwise TunedUp & running smoothly, without any MisFire or VacLeak.
IACValve VacuumLeak Test
With steady Engine Temp >180f & Idle >650rpm, park Tranny, engage ParkBrake, & then unplug IACValve 2Pin
Socket: if the Idle falls to ~500rpm or Engine stalls, no VacLeak; if the 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 below:
- 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