ScanGauge II Questions

I can answer #3. I think it is 8-10 hours. It is printed in the owners manual.

 

1) I keep RPM as low as possible while still keeping the ICE under load, sometimes as low as 1200-1300 even under (low-speed) acceleration. Since you're doing X-gauges, see this for a discussion on using an X-gauge for fuel injector timing as an indirect indicator of ICE load.

2) Not sure why the sudden drop in RPM while accelerating. What's the vehicle speed, how quickly are you accelerating, and what's your SOC? Above 40 MPH, ICE-off conditions still involve the ICE spinning with no fuel flow at about 980 RPM. A sudden dropoff to that level is common under light load conditions. But I can't see it doing it under conditions that require 2000 RPM except possibly with a very high SOC where the car decides on its own to go suddenly into electric-only propulsion.

 

My observations for highway cruising are:

1. On Cruise Control on a flat road, the RPM can vary +/- 300rpm with no discernable variation in ICE noise so I don't think it is measuring just engine rpm.

2. The sweet spot for best speed/good consumption seems to be a LOD figure of 78. Anything over that takes my consumption over 5l/100km (sorry about the metric measurements in Oz). I've found also that keeping the cruising speed at 106kph on the speedo keeps the RPM figure < 2000rpm which keeps the LOD below 78.

3. Around urban areas I try to keep IGN at 14 and TPS at 18 for really good consumption figures. It takes a bit of doing depending on the road/driving conditions but it pays off.

4. I suggest you set up Soc(State of charge) on your SGII as it explains a whole lot of what goes on in the car and why various things are happening(see attachment).

hope this helps

 

Not sure what you're suggesting when you say "it" is not measuring just engine RPM. What is "it"? ScanGauge? If so, are you saying that the RPM gauge somehow is a composite of multiple parameters? How could that be?

Anyway, I too see RPM floating up and down by several hundred RPM without much noticeable change in ICE noise. That's the nature of the beast.

Some use LOD as a sweet spot indicator, but the number of 78 won't work for Tom and his '05. Some of us have compared our LOD readings in the '05 with others in later models. Later models consistently are significantly higher for a given combination of driving conditions, speed and ICE RPM primarily. For me, the LOD sweet spot range is in the 40s to low 50s. See this for more, where discussion on this issue begins at post 14. Best guess is that for either the 2006 or 2007 model year (I can't remember now when a change first showed up), Toyota changed the way the car calculates and reports LOD.

 

I use that range pretty much for all ICE-on conditions when traffic and road conditions allow. At slow speeds on level terrain, it results in acceleration. That's fine, given my extensive use of P&G. ICE RPM indeed can be in the 1200-1300 range. At higher speeds it ends up being steady-state, with RPM generally around 1400-1600, depending on speed.

 

The iMPG to 1/2 MPH rule is what I recommend as a maximum for acceleration, not necessarily a constant target. It pretty consistently produces ICE RPM in the 2200-2400 range across a wide range of speeds. Above that and most everyone seems to agree you're getting into substantially greater ICE inefficiency. See this for more. As you get to the end you'll see where I've gradually evolved to thinking low RPM ranges are OK as long as the ICE is under load. And you'll also read where I explain why I don't care for subjective terms like "brisk" or "gentle" to describe acceleration.

And yes, 1300 RPM would be considered by many to be rather slow acceleration, and by a few, crawling. There's nothing wrong with your car in that regard.

As for braking, that number didn't come from me, and I'm not sure where it came from. Attila Vass, one of the early researchers and CAN-hackers on the Prius II, found in testing that a brake pedal position of 17 as reported by CAN was the most efficient for regeneration. I don't know what that translates to in current flow, but it's about what it takes to slow the car from 45 MPH to 5 MPH in 22 seconds. Frankly, I don't worry too much about efficient braking because any braking is less efficient than not braking. In my hypermiling approach I avoid the brakes as much as possible.

 

I've had my ScanGage for a while and have been frustrated a few times by the results of the calibration procedure after every fillup. A couple root causes for this frustration: 1) the Prius bladder effect makes for unusual large discrepancy in the number of gallons to fill the tank to the same consistent level. 2) I have read that the ScanGage calibration supposedly dampens out this fluctuation over several tanks, but I have yet to see it over dozens of fillups. If I calibrate after each fillup, I see the full swing effect of the bladder anomaly. For example, one tank will result in +10%, then the next at -10%, and so forth, back and forth.

To ease the problem, I do my own mathematical dampening by calibrating it every other fillup. This requires some discipline in recording your total gallons of gas since your last fillup calibration.

Another option is to compare the scan gauge MPG to the Prius' own MPG readout over the same period of time. Odds are that your Prius' MPG readout is accurate to within 2%. At some point you may get "lucky" and the two will be dead-on. At that point, leave it and forget it. Don't recalibrate the Scangauge again.

 

Scangauge is certainly not perfect. Have you noticed sometimes the average MPG or average speed for the current trip keeps changing after the car is turned off?

 

Hi I have a question on the prior work that was done for gen II's adding a whole bunch of useful xgauges . I refer to v 1.6 dated 06/09. Is anyone working on getting these coverted to the Gen III? If not is there a structual problem in doing so?