I've read that some of you have accidentally run out of fuel (gas) .
What happens to the ICE (engine) in these conditions - does it open all its valves and present no load or is it still trying to burn nothing - firing sparks etc

Also I know if you run low on gas in a saab 9-3 it tells you the optimum speed to drive to reach the gas station - and it's quite a high speed 40-50mph.

Is there an optimum speed to drive an IMA with no fuel??

My first post

There's actually less load with all the valves closed since it takes more energy to pump air through the engine than to compress and expand a fixed volume of air in the cylinders. When the HCH II goes into electric only mode the valves are all closed.

Good point

I've read on wiki that the HCH shuts down 3 cylnders when braking.
Does it do that by sliding the cam followers? and why only 3?

no replies in 4 months.......

any stories about running without gas?

No matter what happens, the best you can expect is to coast to a stop. The car is not designed to drive on electric power alone and I would be surprised if the engineers even allowed the assist to keep working without fuel, for the sake of the battery. Heck, even a Prius really can't be expected to go more than a half mile or so and at the risk of over-discharging the pack. My recommendation: Don't run out of gas no matter what you drive.

I also highly doubt that the HCH's IMA could actually move the car to the gas station. When I'm in EV mode in my '07 (with 1-4 bars) on a flat surface, I'm not actually accelerating, but decelerating slower. I think you will have better luck pushing your car to the gas station.

^^^No one replied, because we don't know how/why it shuts down the three cylinders. At least I don't. Maybe everyone else is too lazy

I am positive that the HCH-I will not run without fuel. Once, I was very low on gas in my 2004 HCH, and I stopped at a red light on an upward slope. Auto-stop kicked in, turning the engine off.

After the light turned green, I took my foot off the brake and to the gas, but the engine would not start back up. When I pushed the gas pedal to the floor, the ASST bar showed 100% (full), the engine was silent, and the car barely rolled forward (at half idle-speed) for 2 seconds. I pumped the gas pedal, and the engine eventually came back on, but I was careful to drive efficiently and to turn off Auto-stop (ECON off) until I reached the nearest gas station.

My guess is that the upward slope tilted the gas tank downwards, and the gas pump had trouble feeding enough fuel to the engine for it to start running again. All I know from that experience is that the puny 13-hp electric motor in the HCH-I was not designed and is not capable of propelling the car by itself without the ICE, and that I should not wait until the low-gas light turns on twice before heading to the gas station.

There was a story about 2 years ago about an HCHI that someone ran out of gas and used the electric mode to make it another half mile to the gas station. I don't remember who it was but I definitely remember someone telling the story here.

Remember, the gas in the tank is what cools your fuel pump. When it's near empty, you're reducing the life of the pump.

so i was always curious about my HCH1. what if i run out of gas but with a full battery? i purposely tried it. engine just shuts off and only runs on battery for about half a mile max at 10-15mph