Is 42mpg too low a goal?

[eco_generator]

Originally Posted by Istas

I'm now fairly sure that there is a speedometer cable running from the transmission to the instrument cluster, and that there is a device in the instrument cluster that turns the speedometer cable movement into an electrical signal, that is then sent to the ECU and whatever other devices need it. Which makes me worry once again about the speedometer sticking, and affecting the MPGuino data.

ECU gets completely different signals for coolant temp, speed, and revs IIRC. If you are still worried, get the vrg3 scanner program that will read your ECU information directly. Your speedo problems are just from the cable slipping, check on the transmission side, many times there is a clip missing that keeps pressure on the cable into the tranny.

Get program here: legacycentral bbs :: View topic - An ECU scan tool for turbo and NA owners
If the latest version does not work, try the version before that. You just need to modify a printer cable & make a bootable disc/cd for your laptop to get it to work. As a bonus you will get real numbers for coolant temp, load, & injector pulse width, etc... (Injectors do shut off when coasting down in gear above ~1k RPM)

Your doing excellent work so far. I have the AWD turbo version of this car and it laughs at me when I try to get good gas mileage.

[Istas]

stevey: Thanks, I was hoping it might be something like that.

eco-gen: I would absolutely love to have that much data recorded. I could also hook up weather instrumentation recording temp, humidity and air pressure (and if I wanted to get really silly, wind speed and direction, using vectors to figure out the real values by factoring in my vehicle's speed and direction), and something to record how much uphill or downhill the car is going. Rates of acceleration would also help. However, I don't have a laptop currently. But that sounds really, really cool to do, I will keep it in mind for the future.

And thanks for the tip on the speedometer cable, I'll see if I can take a look at that (or get someone to).

And also thanks for the compliment/encouragement. Yeah, every time in the winter or on a muddy dirt road I find myself wishing I had AWD, I console myself with the thought of gas mileage.

[evolutionmovement]

I only missed it when driving with performance tires in the snow. With half-decent tires, I usually did better than many SUVs. I prefer being able to pull the handbrake and gas it on dirt roads, which would damage the center diff on AWD. Of course, now the handbrake barely works.

[dcb]

Originally Posted by evolutionmovement

I prefer being able to pull the handbrake and gas it on dirt roads..

Or in any really tight turn (snow to dry pavement), fwd and handbrake, killer combo you find in most any eco-box (even useful w/4wd)

http://www.youtube.com/watch?v=bQTML...eature=related

http://www.youtube.com/watch?v=DpKgQ...eature=related

P.S. try using your handbrake in reverse to tighten the shoes back up.

[Istas]

You could spend the big bucks to get one of those special diffs that are disengaged by the handbrake.

"When I get a rental car, I like to drive around with the emergency brake on. That doesn't say a lot about me, but it also doesn't say a lot about the emergency brake. It's more like an emergency-make-the-car-smell-funny lever." -Mitch Hedberg

The MPGuino froze on me this morning when I went for a drive (after putting heatsinks on the power regulator and turning off the backlighting), so I beeped the horn, thinking maybe that would unstick it (as it's tapped into the horn power supply). That's when I discovered that beeping the horn reboots it.

So I'm giving up and wiring it directly to the battery, with its own 3-amp fuse (lowest amp blade fuse in the store, probably won't save the MPGuino but better than nothing) and on/off toggle switch.

[evolutionmovement]

Thanks, DCB, but it's actually the lever that needs to be adjusted as it barely tightens at the top of its travel. Couldn't for the life of me get the nut loose to adjust the cable and it's not like it's rusted. I'll have to figure it soon to get it back on the road, though.

[Istas]

My handbrake's loose too. I tightened it once, guess I'll do it again. I at least can access it by removing the plastic armrest in between the two front seats and tightening it there.

So, I wired the MPGuino directly into the battery, even making my own crappy ring connector out of sheet metal, putting a 3-amp fuse in line with the power, and wiring in a switch too. Hooked it all up, turned on the switch (which has a little LED indicator to tell when it's on), plugged it in, it works just fine.

Until I beep the horn, and it reboots. What the f**k?!

I'm going to learn what I need to learn to wire something into the power line that'll hopefully smooth that out enough so it doesn't happen (like a capacitor (or two?), and possibly an 8 volt regulator so the one on the circuit board of the device doesn't produce as much heat on its own), but the nearest Radio Shack is an hour away. I'll just avoid using my horn on the trip home (not that I usually use it anyway).

[eco_generator]

That is quite the predicament, avoid the accident or avoid losing your mileage data!

Unfortunately you cannot record the data coming from the ECU, but you can watch it real time to look for anomalies or something you want to keep tabs on (like coolant temp after installing a grill block).

[stevey_frac]

Originally Posted by Istas

I'm going to learn what I need to learn to wire something into the power line that'll hopefully smooth that out enough so it doesn't happen (like a capacitor (or two?), and possibly an 8 volt regulator so the one on the circuit board of the device doesn't produce as much heat on its own), but the nearest Radio Shack is an hour away. I'll just avoid using my horn on the trip home (not that I usually use it anyway).

Get yourself a 10 uF ceramic capacitor, and wire it from the power to the ground as close to the MPGuino as you can. That will go a long way towards removing any high frequency noise from the board.

The 5v regulator shouldn't be putting out much heat. The MPGuino can't be using that much power, and typically, small 5V regulators are at least 80% efficient. I would check really really closely for some kind of short? I honestly don't have any experience with the MPGuino, but i'm a computer engineer, and really hot components on this kind of thing sets off my 'something is wrong' alert system. Also, check for other warm components. Most chips these days can run very quickly and produce no discernible heat.

[McTimson]

Where did you connect your ground for the MPGuino?

You could have also wired it into one of the radio lines - it looks like you connected it to the switched 12V line first, but there should also be a constant 12V line going to the stereo.