The high idle/warm-up feature has a number of conditions in order for it to operate, I'll try and recap everything completely since there's a number of questions and also since we're actively wrapping up the development and making some adjustments.

In order for it to activate, the following has to be satisfied:
• Transmission in park/neutral
• Coolant less than 55°C (130°F)
• Ambient temp less than 2°C (36°F)
• Engine run time is longer than 30 sec

The function will deactivate if:
• Transmission is placed into any gear
• Coolant temp rises above 60°C (140°F)
• Ambient temp rises above 4°C (39°F)
• Engine revved over 2000rpm (like releasing the choke on a carburetor engine)

As for the cold box testing, we'll go down to -20F (-28.9°C) since those are the temps at which the owner's manual says the block heater is "required". Our experience in the past indicates that -40C/-40F is, more often than not, not capable to start at unassisted. The cold boxes in automotive use generally go down to -40, to get below that most OEMs test at Eglin AFB in the Florida Panhandle - there you can test and drive at -60F if you want.

However, keep in mind that function doesn't kick in immediately so the after start engine stability is given by the regular combustion parameters, then it transitions to the warm-up mode.

Transitioning into and out of the high idle mode happens via a fast ramp function. The high idle can be turned off by revving the engine just past 2000 rpm and then letting off the pedal, it will then disengage and drop down to normal idle speed. This is helpful to prevent a clunk when doing from park to drive or reverse.

To answer another question, the goal of the function is to provide power entry into the coolant that is equal to or greater than the energy consumption via the heater core (assuming temp set on max hot and blower on max speed). There's no concerns about combustion/exhaust temps themselves specifically, neither with our tune or even the stock one. You can idle the engine for 20hrs a day if you want without consequence, just if you're running the heat too in a cold climate then the coolant temps will continually drop.

As the feature nears it's final state we'll post up the conclusive settings in a dedicated post in our sub-section for reference.

Awesome info on the entry and exit criteria. What does the feature change in engine operation when on (rpm, coolant flow, etc) ty

Sorry if this is a stupid question, but why all the parameters in order for it to be activated? Our diesels at work have a high idle feature that kicks in anytime the truck is idling in Park with the E-Brake engaged, regardless of ambient/coolant/intake temps. This allows for high idle while parked even in the summer to make the ACs work a bit better and to give a boost to the electirical charging systems. i don't think I'd ever need that in my ED, but just wondering why all the specific temps for this application? Thanks -JR

The factory high idle is just an idle bump. The GDE high idle feature is much more involved. With the elevated rpm we are also changing the pilot injection, main timing, VGT position, swirl %, etc. to push more heat to the coolant vs. pumping that heat out the exhaust. This is the main reason we can cut the warm up time in half.

Would it be beneficial to have the high Idle function activate at a higher outside Ambiet Temp? I ask this because I leave in a southern state with usually mild winters at best. Occasionally the temperature reaches the 36 degrees required but the temperatures are usually slightly higher for a majority of the winter. I am still interested in the High Idle as I do not want to run my engine cold. Would it be advisable by you (GDE) to recommend or possibly set the Ambient Temperature interlock a little higher. I was thinking somewhere around 46 Degrees.

Thanks

T-Mills59 wrote:Would it be beneficial to have the high Idle function activate at a higher outside Ambiet Temp? I ask this because I leave in a southern state with usually mild winters at best. Occasionally the temperature reaches the 36 degrees required but the temperatures are usually slightly higher for a majority of the winter. I am still interested in the High Idle as I do not want to run my engine cold. Would it be advisable by you (GDE) to recommend or possibly set the Ambient Temperature interlock a little higher. I was thinking somewhere around 46 Degrees.

Thanks

We could do a custom tune for your vehicle. At your outside temps, the high idle is not really needed.