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Old 07-07-2007, 11:46 PM   #1
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Drove first hybrid-real eye opener

I haven't searched the garage, but I'm not aware of anyone hypermiling a Highlander Hybrid yet. Had the opprotunity to drive one for a few days this week, and I have learned a lot. My thoughts are that the info screen on toyota hybrids is really great, so much feedback is amazing. Keeping the gas engine off is really key. I was honestly shocked by how bad small amounts of throttle can make the mpg. It took a very light throttle to keep it above 20mpg. 10mpg or less is so easy with what I would guess is less than 10% throttle on flat land in town. The whole system is so smooth, the gas engine turns on and off with out any jolt. It is really, really fast when you punch it. Trying to hypermile is way easier in Tulsa than Denver. I am already taking the info I learned from driving the Highlander and using it in my 4runner, I'll get my gaslog updated after I get back.

My last thoughts are that I really need a scanguage, and I think I want a Prius. I know it's been talked about before, but I have to believe that the level of feedback these have would save a really large % of our annual gas usage if they were in every car.
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Old 07-08-2007, 04:15 AM   #2
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I've been saying for some time now (first time on this board though) that every car and small truck should be required to have a real time continuous mpg display.

That would be a hugely instructive tool in teaching drivers about FE.

Digital, with the #s the same size as the ones on the speedometer. And you can't switch it off or into some other mode. We already have all the technology; it would be inexpensive to add to the instrument cluster.
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Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.

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Old 07-08-2007, 08:52 AM   #3
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We already have all the technology
We've had the technology for decades. I've been working on retrofitting a display into my CRX:

It's the driver information display from an '88 Acura Legend... $30 from salvage. The only down side is that it's meant for a V6... The injector signal pulsewidth needs to be scaled 2/3 to work properly with my inline 4. It will still show changes in FE, just not an accurate measure in MPG or l/100km
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Old 07-08-2007, 11:36 AM   #4
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bobski, that's really cool to be reusing that component. I've been considering similiar 2/3 type circuits for other applications too.

Do you know the pinout on that thing or if the mpg/trip function will work with just volts and a vss/injector signal? Or is it integrated into the honda ecu?
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Old 07-08-2007, 03:56 PM   #5
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No, everything is thankfully external. I traced the single wire that runs to the ECU a few days ago... Inside the case, it runs to the no.1 injector pin via a 10k resistor. That's it.
The device actually has a whole bunch of functions: Clock (the unit takes the place of the clock in the legend), distance to empty indicator, trip odo, current fuel economy, average fuel economy, engine oil level, coolant level, washer fluid level, service and oil/filter inverval odos. It isn't installed yet, so there may be other functions lurking in the software that I haven't come across with simple power and ground.

Lets see... The wire from the lighting switch is 12v+ to dim the display, the pink wire from the ECU is the switched ground injector signal via 10k resistor I was talking about above.
The fuel level sending unit needs to output 2-5 ohms when full, 25.5-39.5 ohms at half tank and 105-110 at empty. Conveniently the same values as the CRX sender. I haven't looked at the low fuel sensor... Judging from the circuit diagram, it's the same design as found in other Hondas and Acuras. I can look up specs if you want.
The coolant temp sender needs to output 158 ohms at 54°C/129°F and 32-49 ohms at 85°-110°C/185°-212°F. Also stock CRX values.
The fuel filler door switch is part of the door release lever, so I assume it's triggered momentarily when you pull the release... I haven't investigated further.
The engine oil level switch is in the oil pan... Too much work as far as I'm concerned. The only odd thing I noticed is that the corresponding wire in my donor car showed about 50 ohms of resistance. Not no connection or good continuity, but 50 ohms. The dipstick showed way over full, so I assume water got in the crank case... The switch may have been damaged.
The coolant level switch is built into the lid of the radiator overflow bottle... Simple on/off operation via a reed switch and float with internal magnet. The washer fluid switch is installed in the bottom of the bottle, similar design to the coolant switch.
The speedo and pulser are cable driven, so I assume that's also typical Honda spec... Four 12v pulses per cable revolution or whatever it is.

If you're going junkyarding, the display is on the top of the dash above the radio, HVAC controls and such. Make sure you've got an info display equipped car before you start disassembling things... The standard issue clock looks very similar to the info display when unpowered.
The control unit is above the glove box. Once disconnected from the box, the wiring harness between the display and control box can be pulled back towards the display intact. That way you don't have to deal with resoldering the wad of wires between the two.


So do you have a diagram for a good 2/3 pulsewidth scaler? It strikes me as a problem that might necessitate a processor, but I don't really know. Simply dropping every 3rd pulse might work as well, but it's hard to say how the info center would react to that.
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Old 07-08-2007, 05:12 PM   #6
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I don't have a solid schematic yet, but for an application that can be off a few pulses I'm thinking an analog frequency->voltage->voltage Controlled Oscillator circuit will git 'r done (with appropriate input and output voltage tweaking).


from:
http://www.uoguelph.ca/~antoon/gadgets/pll/pll.html

Here is a frequency to voltage chip that looks like it is built for a magnetic pickup, fyi:
http://www.national.com/pf/LM/LM2917.html

so basically we have
vss->LM2917->trim pot voltage divider to adjust ratio->VCO->voltage divider for instrument input.

Edit: oops, you are trying to divide the injector pulse, not the vss, you need to detect the duty cycle (read inductor) and make a new signal with the appropriate duty cycle...

edit: oops, looks like we are hikjacking a thread...
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Old 07-08-2007, 07:38 PM   #7
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Quote:
Originally Posted by brucepick View Post
I've been saying for some time now (first time on this board though) that every car and small truck should be required to have a real time continuous mpg display.

That would be a hugely instructive tool in teaching drivers about FE.

Digital, with the #s the same size as the ones on the speedometer. And you can't switch it off or into some other mode. We already have all the technology; it would be inexpensive to add to the instrument cluster.
Absolutely, instant and avg FE should have been in cars for many years now. Always was disappointed it was not at least an option on new cars. Oh well, at least I've got a ScanGauge now....
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Old 07-09-2007, 05:52 AM   #8
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Quote:
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edit: oops, looks like we are hikjacking a thread...
Yeah, I have a habit of doing that.
Starting a new one.
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Old 07-09-2007, 12:51 PM   #9
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I like where it's going!
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