Say hello to the Mighty Mira!

[Matt Timion]

Originally Posted by Mighty Mira

That's probably all I will need, then. Of course, I will need to check that it actually exists, and to remove the dash.

"Bother", said Pooh.

I think in theory you should be able to remove the cluster without removing the dash.

Oh, and that was a good link. I saved the info for future use if we ever start selling MPG computers here.

[Mighty Mira]

Originally Posted by Matt Timion

I think in theory you should be able to remove the cluster without removing the dash.

Yes... if the theory assumes that I am either 5 years old or have plastic arms 2 inches in diameter.

[Mighty Mira]

Actually Matt, you are right.

I just went down to buy an automotive multimeter (about $60 Aus, or $50 USD).

I unscrewed 2 screws on the cluster and 3 behind to access the cluster. There were two connectors in back. One which I assume is some sort of mechanical speed signal. I'm not sure what it was exactly, it had quite a bit of grease on it. I figured it was something mechanical and not electrical, as otherwise, why the grease? I managed to get that out. There was also a 16 pin (from memory) connector that plugged into the back that I managed to get out with a bit of work.

And so, with trepidation, I had a look at the screws on the back.

Behind instrument cluster -bottom screw at speedo head

Hmmm. Speedo... bottom screw... Was there a ground to attach in order to get a proper signal? There was! I hooked the black alligator clip to the GND signal, and the red alligator clip to the mysterious bottom screw. Dangling the wires through the back down near the peddles, I hooked it up to the multimeter.

Then I hooked the other stuff back up. The mechanical grease connector didn't feel right, and wasn't. When I started it up, I saw no increase in kph.

Stopping, I jammed it back in and it seemed like it seated properly. I was rather worried, because I thought it might have some mechanism whereby if you screwed with it, it wouldn't work again to prevent winding back the odomoter.

However, as I went faster this time, the speedometer appeared to be functional.

And what's more, as I turned the multimeter to "RPM", I got a signal that went higher as I went faster, went slower as I went slower, and did the same independent of gear.

I HAD FOUND THE VSS AND VERIFIED IT!!!!!

So now it's only a matter of finding a convenient injector signal. I can either buy a stamp myself to program, or buy the Supermid.

But no matter what, this sure beats having to mess around with mechanical vss signals. I can do several things now, measure l/100km on the fly and also attach a cruise control unit, both of which I have wanted to do.

Anyway, I am happy, that gives me a feeling of accomplishment.

[philmcneal]

welcome, how are your bump starts? i'm curious to hear your results. Although if your stats are correct then that's crappy power to weight ratio but i bet its easy to park around town!

[Mighty Mira]

I can bump start almost every time (take it to mean clutch starts). However, still sometimes it starts with a bump, and it's a little less predictable than I'd like.

Is it better to change to a high gear for the rpms, or a low gear? I started off using a low gear, but now I think it's working better with a high gear.

I should probably stop it, because just reading the manual it says "Caution: A large amount of unburned gas introduced into the catalytic converter may overheat the converter, which may cause a fire. To prevent this and other damages, observe the followings; ... Do not turn off the engine while vehicle is moving. Do not push or pull start your vehicle."

So far no problems though.

BTW, here are the vehicle stats:
Length: 3.295m
Width: 1.395m
Height: 1.415m
Wheelbase: 2.28m
Fuel tank capacity: 32l
Gross Vehicle Weight: 1040kg.

Now, GVW is usually 300-400kg more than Kerb Weight (just figured out through googling). So kerb weight should be 640-740kg, which is right around what I want.

From what I find, it's not underpowered at all. (Of course, it will be even better when I have shaved off 50% of the drag.)

[Mighty Mira]

A bit more about the VSS:

It looks like however the rpm is configured, it measures the vehicle's speed perfectly. I am using the digitor q 1585 multimeter, rpmx10 setting. It shows a speed of 25kph as 250, and keeps going. This means that according to the manual, if it were measuring rpm, a 250 signal means 2500rpm.

Hmmm. since 1kph is obviously 10 on the guage, or 100rpm, what signal is actually being sent? Well, since the rpm meter is designed to be connected via an inductive pickup to a spark plug lead, that means that at 1kph the metre will be sending 100 pulses per minute. Or 1.6667 pulses per second.

There are a bunch of other screws at the back of the instrument cluster. I have a mind to attach wires to all of them and see if I can reverse engineer them. Perhaps I will get lucky and find an RPM signal, an INJ signal, or a fuel guage signal (very likely).

Anyway, I'm very lucky that the VSS signal was so easy to interpret, not requiring any fancy calibration.

[SVOboy]

Good job with the VSS!

I bump start in the highest gear I can for the speed, makes it smoother.

Anyway, mehbe you'll whip something up in terms of instrumentation, I wish I had the know-how!

[philmcneal]

To start the car smoothly with the clutch, depending on speed its best to start in the higher gear so that engine revs won't soar too high when coming back alive again. Fuel economy pros use this technique to turn off their engine then putting the shifter into Neutral when acceleration is not needed, and then when a lower speed has been reached (say 30 mph or 50km/h) then one would attempt to restart the car with the clutch in 5th gear, since this method is much less harsh than turning on the engine with the key. One would have the clutch disengaged (clutch pedal in) and then from Neutral slide it into 5th. Then as you let rengage the clutch (slowly releasing to the friction point) you will feel it gripping the engine. Immediately let off the clutch pedal till the engine starts firing its cylinders and then right away press the clutch again to avoid aftershock. If done correctly within the second, the clutch should absorb any NVH (noise, vibration, harshness) and engine revs should rise to about 1100 rpms. If engine fails to start try a lower gear, but remember the lower the gear, the more clutch you need to absorb the greater aftershock. Engine revs could be higher during a bump start like 1500 rpms or 2000 although you want to keep these revs as low as possible in order to reduce wear and tear on the engine (rev too low and the engine won't come back on, one must know which gear to start with so that NVH is controllable for all speeds... in this case its harder to control as your momentum decreases). As the revs fall and settle to idle, one should rev match into the appropiate gear and then accelerate their way to desired speed (usualy 40mph or 70km/h before areodynamic losses are prevalant) and then repeat for maximum fuel economy. I suggest refining this technique before attempting to use in real world driving situations as if fallen to the wrong hands can be deadly (like speeding). A master with this technique can recall the engine within half a second and start accelerating as soon as that second is done with no NVH to either the driver or the passengers. And the mileage increases are reported to beat EPA highway estimates in the CITY. If one hasn't noticed why not just coast in Neutral? Simply because as your momentum decreases, the same amount of fuel used to keep the engine running won't be worth it as opposed to coasting with the engine off and mileage is still increased even at very low speeds. There is no payback for fuel coasting with the engine off as opposed to coasting with the engine on in Neutral. In Neutral one has to be travelling at higher speeds to gain the mileage benifits of coasting (since when one is in gear, engine braking prevents the car from travelling far with just momentum), but with the engine off that rule is broken and mileage soars upward at any speeds. Its just a matter of learning how to turn on one's engine when they need it the most as well as maintaining safety, passenger comfort and not overdraining your 12 volt battery.

something to helkp with your bump starts ^ higher gear the smoother, i go as low as 2nd when my speeds are low but i try to make it a high gear.

[Mighty Mira]

Well, I had another look at my instrument cluster, this time in more detail. And got some pictures...

As you can see, there is a 22 pin connector in addition to the mechanical odometer cable (or whatever it is). I reverse engineered the pins as best I could with the new multimeter and some educated guesswork judging by which conductors lead to which lights or went to connectors behind which guages.

[Mighty Mira]

Another great bonus - I was tracing the route that the injector wires take, traced them through the firewall, and lo and behold, I found the ECU! It sits right under the passenger side of dash, and is trivial to access (although I need to get a proper socket set to get the bolts off; my socket screwdriver won't cut it.).

This means that no longer do I have to remove the whole dashboard to get at what I need to.

At the moment I'm a bit awestruck at all the things I get to play with: a VSS, INJ signal, and hopefully an RPM signal (which I can get inductively from the spark plug anyway).

That means I can make:
-l/100km guage (Need VSS, INJ)
-digital speedometer (Need VSS)
-digital tachometer (Need RPM)
-digital temperature signal (useful for grille testing) (Need Temp signal)
-digital tank guage (also how many km left to travel, worst case). (INJ)

All of which should be relatively easy once I understand how to setup the basic stamp and the LCD screens. This looks helpful.

So, my basic plan of attack is now:
1) Get basic stamp, LCD, board, etc, everything needed for final project.
2) Pry off ECU to get a good look at it, see if there is any schematic on the back, and see how to easily detach the various wire bundles for splicing. (Need socket set).
3) Find RPM signal for tachometer.
4) Use a PC oscilloscope through soundcard setup to analyze the various signals, such as this one.
5) Splice various wires such that I have easy access to every signal I need.
6) Start programming the stamp and testing out the basics of the device, troubleshooting until finished.

I think that's it.