I finally got my MPG readout adjuster installed...
- Thread starter Iowa4Runner
- Start date
Vortec4800
New member
rando said:
Hooray!
Iowa4Runner
New member
Vortec4800 said:
Keep in mind that a person of average intelligence might appear smart if they have really nerdy hobbies. Such is the case with me...
Kmvreter
New member
If this works...
I'm not good with electronics (something about a toaster accident as a youngster scared me off.) "If this circuit works, it can be assembled for about $5 or less." Can we take it to Toyota at the corporate level and let them engineer in the fix? I've complained at the stealership about the mpg readout but as usual that falls on deaf ears.
I'm not good with electronics (something about a toaster accident as a youngster scared me off.) "If this circuit works, it can be assembled for about $5 or less." Can we take it to Toyota at the corporate level and let them engineer in the fix? I've complained at the stealership about the mpg readout but as usual that falls on deaf ears.
Iowa4Runner
New member
Re: If this works...
The really frustrating thing about this is that it would take zero hardware for Toyota to fix the MPG problem. All the engineers have to do is adjust a few program lines and that's it. The problem seems to be in getting the information to the engineers and getting the revised code to the assembly line. The engineering effort would be trivial.
Kmvreter said:
The really frustrating thing about this is that it would take zero hardware for Toyota to fix the MPG problem. All the engineers have to do is adjust a few program lines and that's it. The problem seems to be in getting the information to the engineers and getting the revised code to the assembly line. The engineering effort would be trivial.
Iowa4Runner
New member
rando said:
A while back I looked into making a homemade PIC flasher, but all the designs I found weren't supported very well and could only flash a few types of microcontrollers. Knowing that I'd eventually be implementing a wide range of PIC controllers, I decided to spring for a $200 PICStart Plus programmer. If you want to try a homebrew flasher, you might have some luck with some of the designs at:
http://www.piclist.org/techref/microchip/devprogs.htm
I have a spare 12F683 that I could program with whatever code you'd like and send to you...
rando
Senior Member
Iowa4Runner said:
That would take all of the fun out things now wouldn't it? Thanks for the offer -- it's exceptionally cool of you! I'm sure someone else around here might be more in need than I am. I've already got a few PICs headed my way.
Do you do MCU solution design for work or pleasure?
Iowa4Runner
New member
rando said:
It's strictly a hobby that I've just recently had an interest in. I'm kicking myself now for not taking some MCU classes when I was in school. For some reason I just wasn't that interested then. The fact that the professor who taught the classes was a jerk didn't help either...
Kmvreter
New member
Toyota fix...
"...it would take zero hardware for Toyota to fix the MPG problem. All the engineers have to do is adjust a few program lines and that's it. The problem seems to be in getting the information to the engineers..."
I know this forum is not formally directly connected to Toyota but maybe the moderators or others (maybe guys reading this that work at dealerships) know of a corporate connection they can enlighten on the existence of this forum and all the good points being made. (Sorry for hijacking the thread.)
"...it would take zero hardware for Toyota to fix the MPG problem. All the engineers have to do is adjust a few program lines and that's it. The problem seems to be in getting the information to the engineers..."
I know this forum is not formally directly connected to Toyota but maybe the moderators or others (maybe guys reading this that work at dealerships) know of a corporate connection they can enlighten on the existence of this forum and all the good points being made. (Sorry for hijacking the thread.)
rando
Senior Member
I think the "zero hardware" comment is more directed at fixing the production line. The fact of the matter is, the production trip computers most likely use a ROM based MCU or at least have had their Code protection bits set. This means the few lines of code they need to fix probably cannot be done in the field.
In other words, Toyota probably would need to replace the trip computer hardware to give us the fix. Unless somebody can make the case to them that it's safety related, I don't see this happening.
In other words, Toyota probably would need to replace the trip computer hardware to give us the fix. Unless somebody can make the case to them that it's safety related, I don't see this happening.
Duc Hunter
New member
Why don't we lesser folks talk about getting Iowa to make this for us as a part to install. Any progress report on how it works relative to your actual/hand calculated mileage?
Iowa4Runner
New member
Duc Hunter said:
I'm still only about 1/2 way through my first tank of gas so I haven't done any mileage calculation yet. The last two days the weather has been really nice so I took the ZX-9R to work. :zoom: The MPG readout on the 4Runner has been hovering around 16.6 - 16.7 MPG which is about what my calculations usually come out to be. Driving 75-80 in windy areas really seems to take a toll on mileage. The real test will be in varying the driving conditions. I need to tow a large trailer or something for a tankful and then spend a tank geezing out at 50 MPH on a country road. I'd feel better about this project knowing the MPG read accurately at the extremes.
About me making these for people, that might be a bit much. It took a fair about of time and effort to build this circuit and I wasn't planning on making more. I'd be willing to program the chips for people as long as I didn't get overwhelmed with requests. One thing I need to be more vocal about is the risk this poses to your 4Runner and it's occupants. If the wire that comes from the fuel injector gets grounded while driving, it could cause a SERIOUS problem. The fuel injector might stay open continuously which could lead to extensive damage and a fire. Modifying the wiring in this way might also void your warranty. Don't get me wrong, I'd love to be able to equip everyone here with an honest MPG computer but I don't really have the time and I don't want to assume the liability. Sorry
rando
Senior Member
Iowa4Runner said:Don't get me wrong, I'd love to be able to equip everyone here with an honest MPG computer but I don't really have the time and I don't want to assume the liability. Sorry
I second that opinion. Engine damage, an accident, fire and/or death all appear to be very real possibilities with this modification -- if something goes wrong.
Iowa4Runner posted everything you need to try this yourself. If you don't understand it and the risks, you shouldn't even consider doing this. In any case, you should probably wait to give this thing time to mature.
@Iowa4Runner: Do you happen to know what the minimum turn-on current is for the injector? Suppose a catastropic failure in the PIC pulls pin 4 hard to ground. Will the ~5K resistor limit current flow enough to prevent accidental inector turn-on?
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Iowa4Runner
New member
rando said:
That's the plan, that any one of the series 1K resistors will limit the current enough to prevent the injector from turning on if the wire gets grounded somewhere "downstream". I don't know what the turn-on current is for the injectors, put their resistance is about 12 ohms if I recall correctly. Actually, talking about this reminds me of something I wanted to check. I'll be back...
Iowa4Runner
New member
... OK false alarm. So getting back to protecting 4Runners from accidental fuel injector turn-on. If the fuel injector steady state current is about an amp then 13.3 mA (13.5/1012) shouldn't be nearly enough to turn it on. To be more certain I should do some research on the fuel injectors and find out what the minimum turn on current is. The problem with that is Toyota most likely used Denso injectors, and Denso is frighteningly inept when it comes to supplying information about OEM parts.
rando
Senior Member
Alternatively, you could measure the current draw of the trip computer on the injector line. The minimum turn-on current must be greater than that amount. If each of your resistors can keep the current below that amount (and still high enough to satisfy the PIC) then the circuit should be operationally safe.
