lc0338 wrote:
Here is information from my 2014 Ram 5500 owners manual about high idle feature (Automatic transmission only)
* The Idle-up feature uses the speed control switches to increase engine idle speed and quickly warm the vehicle's interior. This feature must be enabled by your dealer. See your local dealer.
* With the transmission in PARK, the parking brake applied, and the engine running, push the speed control ON/OFF switch to on, then push the set button.
* The engine RPM will go up to 1100 rpm. To increase the RPM, push and hold the RESUME/ACCEL button and the idle speed will increase to approximately 1500 RPM. To decrease the RPM, push and hold the SET/DECEL button and the idle speed will decrease to approximately 1100 RPM.
* To cancel the idle-up feature, either push the cancel switch, push the ON/OFF switch or push the brake pedal.
My high idle is activated and my tranny also has a PTO so I suppose that 1100 RPM is adequate for making sure the excess fuel gets burned off and the availability to increase RPM to 1500 RPM is to support the PTO and it's use.
Here is what the manual says about engine idling:
Avoid prolonged engine idling. Long periods of idling may be harmful to your engine because combustion chamber temperatures can drop so low that the fuel may not burn completely.
Incomplete combustion allows carbon and varnish to form on piston rings, engine valves, and injector nozzles. Also, the unburned fuel can enter the crankcase diluting the oil and causing rapid wear to the engine.
If the engine is allowed to idle, under some conditions the idle speed may increase to 900 RPM then return to normal idle speed. This is normal operation.
Thanks, that's great information. Maybe I'll set my high idle to 1100.
