mesaroad
New Member
- Joined
- September 14, 2012
- Messages
- 2
- Reaction score
- 0
- City, State
- Colorado
- Year, Model & Trim Level
- 2003 Ford Ranger FX4
Thanks Pontisteve for the excellent ideas. Before chasing vacuum leaks, which sounds like the likely culprit, could a faulty IAC with a weak internal spring, allowing it to stay open without a signal from the PCM to do so, cause my symptoms? Presently when the engine is warm and finally idling at 750, the rpm's will drop to 550 when I disconnect the IAC. This suggests that the IAC opens on demand. Should it also be open and allowing additional air flow between shifts or when coasting in neutral? I would guess that it should be closed at these times, but if it remained open, the rpm's would over-rev between shifts (as it does) and hang higher than 750 rpm when coasting downhill in neutral (as it does). Could I test this idea by disconnecting the IAC, adjusting the throttle to idle at 750 on its own, and driving the truck without an IAC? If a vacuum leak was still the culprit, the over-revving symptoms should continue. Are there other reasons not to operate the truck without an IAC other than the challenge of cold weather starting and warmup?