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! Hold the foot brake with your left foot, hard! Shift into "R". Pulse the accelerator. --> engine stops Shift into "N". Use right foot to hold brake, normally 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.
Bob, This is very cool. Your Reverse trick, plus the cited "B-N-D" trick are in effect ICE-ON suppressors, probably the more effective us of the EV Mode switch. And it's free. Wish this was posted 6 weeks ago. I might not have got the EV switch and saved some doh-re-me... live and learn Oh well, the EV switch does offer some additional opportunities to kill the ICE at speeds less than 32 MPH... for some very small MPG gains. Another slight benefit of the EV switch is that before the ICE is warmed up, slipping into EV mode does give access to a "no arrows glide" which is normally not accessable... Another chance for small MPG gains... But, like change in your pocket(book), they do add up over time.
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
A bit tangential, and maybe deserving of its own thread, but the idea arose from this thread...so bear with me. This is for the NWH20 Prius. I sometimes have short stops after full warm up..for instance when picking up my kids from school. When I get back in the car the ICE/Coolant temp are still above 157F. However I go into the usual S1 cycle. The Problem: When pulling out of a parking lot I sometimes have to stop to wait for a while to enter traffic. I've noticed that the Prius will continue to run and stay in S1 if I'm just sitting there, whereas if I'm 'on the move' the S1 time is markedly shorter. Solution?: Yesterday I encountered just this situation. While waiting to enter traffic with a fully warm ICE I was stuck in S1 (1275rpm constant ICE run). I remembered this thread and tried going into Reverse. IMMEDIATELY, the ICE shut off! I went back into Drive, it stayed off, and when I pulled into traffic I was in S4 (b/c I'd been in S4 prior to my stop). This needs to be tested to prove repeatability, but I have little doubt this'll save me some unnecessary S1 time.
This is interesting - I've had situations myself where i've asked "Wth is the ICE running? I'm warmed up, should be in S4" For some reason the computer is making the decision to drop to S1, and the R then D is clearly telling the engine to re-consider it's mode.
I recently installed the EV switch, and trying to integrate it's use into an overall high FE/MPG strategy is really messing with my head. Anyway, because I'm paying particularly close attention to the ICE being on when the car is stationary, I'm seeing times when I should be In S4 -- I've got a ScanGauge for temps -- but the ICE just will not shut down at stops with coolant temps above 157 F. This is in stop and go urban traffic with short ICE runs and frequent ICE-OFF, no arrow glides. Trying to rationalize what's going on when the ICE won't shut down when the car is stopped, I've come to the conclusion that it may be low catalytic converter temps that are dictating the ICE-ON condition. Is there any possibility that this is the case?
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
One minor addition. Not that it applies in any normal circumstances, but in R the ICE will turn on if the HV battery is low enough. I know at a stop in reverse the ICE will run, and for sure under 10mph. I don't know what happens over 10mph in reverse and a low HV battery, I didn't want to find out which system it tries to protect more.
