Please explain what "blip the throttle to go back in negative split mode" means?
The C-Max uses what's called "Powersplit" architecture. It consists for 3 motors - Internal Combustion Engine (ICE), an Electric Traction Motor and a Generator Motor. People will refer to the Electric Motor and Generator Motor as the EV which is short for electric vehicle.
The diagram below shows the components.
The Planetary Gear System allows the motors to power the vehicle simultaneously. Ford has employed a Continuously Variable Transmission (CVT) for the C-Max transmission so it has no gears. If you search for these terms in Google you find multiple articles describing the technologies in detail.
There are four modes for how the C-Max uses the three engines.
The three major ones which are straightforward to understand:
- Series Mode - When the car is stopped and the ICE is running to charge the batteries or keep the car warm.
- Positive Split Mode - When the car is moving and the ICE is running to move the car and charge the battery.
- Electric Mode - When the car is moving but the ICE is off and the EV is moving the car on its own.
The fourth mode is a bit more difficult to explain. It is called Negative Split Mode or as some refer to on the site as ICE High.
Negative Split Mode is used to aid the ICE when traveling at high speeds. In this mode the Generator Motor is actually used to help power the car allowing the ICE to idle as low as possible. This mode is only possible when the batteries are almost fully charged. This mode kicked in above 63 MPH before the 13B07 update as Electric Mode was only possible less than 63 MPH. Post 13B07 the threshold was raised from 63 MPH to 85 MPH.
The following diagram is useful for understanding the 13B07 upgrade.
The ECM and HPCM are essentially computers that control the car's ICE, EV and gear components. They contain the algorithms that determine how the various components of the car will work for a given situation. The software that determines these algorithms was updated by 13B07 to allow for better MPG while driving.
Post 13B07 when in ECO cruise and below 85 MPH the car will attempt to alternate between Positive Split Mode and Electric Mode for optimal gas mileage and will not use Negative Split Mode. By blipping (I am assuming pushing the accelerator briefly) while in ECO cruise it will make the car seek Negative Split Mode as opposed to alternating between Positive Split Mode and Electric Mode. I haven't tried this technique so I'll defer to those who have experience with it.
Personally I don't use ECO cruise much. I find that I get better mileage by having full control over acceleration. Since the 13B07 upgrade I've been averaging 50+ MPG. It takes knowledge of the modes, an understanding of the gauges and driving discipline to achieve the mileage. The great thing is I am not compromising on speed as I am staying up with traffic if not passing others on occasion. I will say that I could easily do worse if I didn't drive smartly. The C-Max definitely allows for acceleration and driving styles that won't achieve optimal mileage. Weather has been optimal though and I expect a hit in mileage as colder weather approaches.
I rented a Prius a few weeks ago while traveling for work. Toyota has taken a different approach than Ford. They have made the engines and batteries smaller, styled the car for optimal aerodynamics, and tuned the control modules for optimal MPG. The Prius lives in its equivalent of Negative Split Mode as the ICE kicks in above 30 MPH and has achieved great mileage when traveling at 65 to 75 MPH. This results in great overall MPG but at the cost of acceleration, styling and handling. I got 50+ (about the same) with the Prius but didn't really have to worry about how I drove. The big differences for me that make me desire the C-Max over the Prius are the ability for quicker acceleration if needed, styling that is more comfortable with greater visibility and handling that is sportier.
Edited by nsteblay, 18 August 2013 - 06:06 AM.