KGenaidy

Hi Benfb,

It's very possible that given the driving conditions ... you are getting great mileage ... and 38.3 mpg life to date is certainly very respectable. I have always thought that my commute played into the strengths of the HS. Lately ... I have been having to do more highway driving ... and it is producing lower mpg results.

I think of the s1-s4 stages as the "rules" that control what hybrid capabilities are available. S3 and s4 are nearly identical ... other than if in s3 ... the "querky" computer behavior of wanting to get into s4 can expose itself. I am aware of 2 ways to get to s4 and both are dependent upon the coolant temp reaching at least 160F degrees. Coming to an almost stop while engine is running (crawling at 0-3 mph) or coming to a full stop and "blipping" it if the engine isn't running ... then waiting for the engine to shut off after 7-10 seconds. Once in a while the computer and I are in sync as we are coming to a stop and I just wait the 7-10 sec for the engine to shut off. Once the transitition to s4 is made ... I have found the HS to stay in the s4 stage until the next time the vehicle is turned off.

I suspect that a lot of the behavior that is being described is because of being in s3 mode and not successfully getting to s4. I know that I certainly don't care for this behavior from the HS ... which is my whole reasoning for forcing s4 as early as possible.

I was very surprised (and continue to be) at how long it takes to warm up the coolant temp when using pulse and glide (P&G) as soon as it "is available". It has shown me that "surely the engines warm by now" wasn't in sync with what was actually happening at the engine. It's starting to get warm in TX now and the coolant is warming up much faster ... so w/in 5 minutes I can usually force it into s4 as driving conditions allow.

It would be great if someone from Lexus could explain this to all of us. I suspect I'm doing a very poor job trying to explain this.

hyperme

Benfb, I find it very unusual that after your long commute home, your ICE doesn't shut down (or at least cut off the fuel if your speed is 42mph or greater) on that last downhill toward home. I assume your coasting in Drive and not Neutral. That sounds like a problem with the system.

In an earlier post, you asked for other's observations with their HS. I've been tracking some numbers this past week (my 1st week with the car), here they are for my typical commute:

Startup in morning:
-Starting ICE temp (per SGII): 75deg (in garage)
-Ambient temp: 61deg
-Is EV mode available at startup: no
-I assume I'm in S1 (stage 1)

1st stop sign (after ~30sec from startup):
-ICE temp: 96deg
-does ICE shut off: no
-EV mode: not available
-electric mode (not EV mode): also not available
-I assume I'm in S1 (stage 1)

Coasting in Drive (after ~45sec from startup):
-coasting at 20mph
-ICE temp: 113deg
-ICE does not shut off in "D" (drive) or "B"
-I assume I'm in S1 (stage 1)

2nd stop sign (after ~1min from startup):
-ICE temp: 119deg
-does ICE shut off: no
-EV mode: not available
-electric mode (not EV mode): also not available
-I assume I'm in S1 (stage 1)

3rd stop sign (after ~90sec from startup):
-ICE temp: 132deg
-does ICE shut off: yes, after 3 seconds
-EV mode: not available
-electric mode (not EV mode): also not available
-I assume I'm in S2 (stage 2)

Coasting in Drive (after ~2min from startup):
-coasting at 25mph
-ICE temp: 156deg
-ICE does shut off in "D" (drive) and also in "B": SGII reports 0rpm & 0gph
-I assume I'm in S3 (stage 3)

4th stop sign (after ~3min from startup):
-ICE temp: 157deg (didn't warm up much more due to coasting above)
-does ICE shut off: yes, after 3 seconds
-EV mode: forgot to test if this was available
-electric mode (not EV mode): yes, this is now available (so I assume EV mode would have been available)
-I assume I'm in S3 (stage 3)

Coasting in Drive (after ~6min from startup):
-coasting at 47mph (freeway)
-ICE temp: 175deg
-ICE shuts off in "D" (drive): actually ICE doesn't shut down but I have DFCO
-I assume I'm in S3 (stage 3)

4th stop sign (after ~20min from startup):
-ICE temp: 186deg
-does ICE shut off: was already off since I coasted to a stop
-EV mode: yes, this was now available
-electric mode (not EV mode): not applicable since I was already in EV mode
-not sure of the stage here, either S3 or S4 or the transition between the two

I will continue to monitor this for awhile until I have a better understanding of how the HS reacts in different situations. Let me know if this info is at all usefull or helpfull.