Backup trick - NHW11

So far, my experiments show this works with the NHW11. It may also work with the NHW20. However, it is a little "exciting" the first few times and somewhat risky if you are not practiced.

PROBLEM

Until the coolant reaches 70 C, the engine of the NHW11 runs regardless. If you are stopped at a light or stop sign due to traffic, the idling engine can make a significant impact on your mileage. However, turning off the car induces a second, more wasteful engine STOP/START cycle.

SOLUTION

NOTE: be sure to practice this with no other traffic around!

1. Hold the foot brake with your left foot, hard!
2. Shift into "R".
3. Pulse the accelerator. --> engine stops
4. Shift into "N".
5. Use right foot to hold brake, normally
6. When light changes, shift into "D", release brake, and drive off

SYNOPSIS

This works because the NHW11 turns off the engine when going in reverse. However, it appears you only have to be in "R" and hit the accelerator. It doesn't notice that the car is being held stationary by the power front disk brakes. So pulsing the accelerator causes it to shutdown the ICE. Then you slip into "N" to keep it from restarting the ICE.

Now this process can be a little exciting and the steps have to be follow precisely. It is especially important that the left foot hold the brake HARD as backing into a car behind you will result in further delays. However, it seems to work. This may also work with the NHW20 but I do not have a test vehicle.

Bob Wilson

ps. Another method was described in this post.

 

Subsequent testing has revealed the backup trick is most effective when the engine coolant is lower than 40 C and even better when below 30 C. Apparently there is brief 'engine off' command sent to the engine when the car goes into "R" and another when the accelerator is pressed. This causes a noticeable 'bump' from the engine compartment. However, the engine continues to run if the coolant is warm enough.

I still find this trick useful because when the engine is coolest, the fuel consumption is worst. So being able to stop the engine early in the warm-up cycle helps. Later would be nice but sitting in "N" isn't too bad.

Bob Wilson

 

We're all at the same point. My experience and data so far shows:

• reliable at 40 C and below - the engine stops every time
• unreliable above 40 C - it is hard to predict because sometimes it works and other times not
• first attempt seems likely - first attempts are fairly successful but only subsequent attempts seem to fail

The more information we get, the better. Perhaps the next generation Prius and all Toyota hybrids will adopt this 'auto-stop' at all temperatures and running conditions. Only under low SOC should the engine run to protect the battery.

Bob Wilson