Say hello to the Mighty Mira!

[Mighty Mira]

BTW, I just went and copied down all the colors of the wires and the pinouts they correspond to. I will get that up shortly.

However, I did have a look at the distributor like you told me to. I am fairly new to engines, but I found the spark plug leads and followed them from the cylinders to a cylindrical thing on the end of the motor, with three heads pointed off at 60 degrees spacing. I figured that this is the distributor.

So, this has 4 wires coming off it - two come off the end and are white/cream, and black/red, both with two silver bars. They are larger wires, and furthest from the engine.

Now closer to the engine are two smaller wires, signal wires obviously. They are blue/yellow and blue/green. I traced them to the N+ and N- in the ECU. I'm guessing that these are going to give rpm. I can probably test that with my multimeter now.

ALso, my injectors are hard to get at. I can look at the first one, which has white/green and black/yellow coloring. The next one is impossible to get at properly, and the only thing I can do is to lift up the shielding slightly. They too look white/green black/yellow. ????

But when I have a look at the ECU wires, there is +B1 and +B2 showing black/yellow, both are thick wires. Also, there is a white/green wire, that is marked #10. Or if I am mistaken, there is also E01 and E02 which are both white, black and thick.

[Mighty Mira]

I have a feeling that I may need to install an aftermarket BAP sensor on the car. I'll have to do some research to figure out how much resolution these devices have.

My basic purpose with this is to enable the FE meter to track changes in elevation.

[SVOboy]

Damn that ECU is bare as hell! Anyway, no BAP, what do you need it for?

Only 4 wires on the dizzy! Geez.

Black/yellow is the power the the injectors, you'll want the other wire, which is a switched ground, for injector pulse signal.

The rpm wire should only be one wire, hmm, odd. I wonder what sensors are in the dizzy, if any. I wonder if you even have these sensors? They didn't seem to be on the ecu side of things.

Perplexing.

[Mighty Mira]

I've finally been able to figure out my highway mpg. Highway is 50mpg (4.7l/100km or 21.3km/l), City is 31.3mpg (7.5l/100km or 13km/l).

Note that the highway wasn't completely highway, but maybe 65-70%. I wouldn't really consider it to be a true highway run. Which means that perhaps unmodified, I might be able to get what?

Let's see, if I travel 45km at city and use 3.46l... and I travel 128km and use a total of 6l, then the highway section I used 2.54l and travelled 83km, giving me 3.06l/100km!

While I don't think it is quite that good, I would certainly be pleased if it was! That would be 70mpg.

I did pump the tyres up to 50psi though.

[Mighty Mira]

I just found myself an old oscilloscope that should do the trick. Now I will be able to examine the signals first hand, which should prove interesting. I may need someone else to drive the car though.

Well, at least for the VSS.

[Mighty Mira]

Ok, I have set up my oscilloscope to run off an inverter powered by the cigarette lighter. I did some cursory testing - the scope measures 12 volts coming off the battery, so that seems to be fine.

I looked at the VSS. The VSS triggers a pulse every time the wheels turn a certain amount. That pulse is about 4 Volts. The waveform looks like so (it returns to the same level as it started, excuse my hasty drawing) :



I had a brief look at some of the ECU pins. There is one that varies the pulse width compared to how hard I mash the throttle. It obviously has to be either the rpm, the TPS, or the INJ signal. I suppose the best way to test that is to get on the highway in 5th gear and mash the throttle. If it doesn't change, then obviously it's got to be RPM. If it does change, then it's either the INJ or the TPS.

I'm not sure how to distinguish the TPS from the INJ. Well, I imagine that the INJ will vary according to the RPM, it's just that the pulse width will change. Whereas I'd imagine that the TPS will not depend on RPM at all. Thus if we know a signal is either the TPS or RPM, then a change in RPM should tell the difference.

e.g.:
1. Go to highway speed in fifth gear. Step on the gas. If no change, signal is RPM. If signal changes, go to 2.

2. Go to second gear. Put the throttle down a reasonable amount. As the rpms climb, note the signal. Does something increase frequency? Then it's INJ. If not, then it's TPS.

[MetroMPG]

Originally Posted by Mighty Mira

I'm not sure how to distinguish the TPS from the INJ.

My car's ECU / sensors stay active if I stall the engine and leave the key in the "run" position. If your car is the same, you could stall it intentionally (while stopped) and then observe sensor inputs with the engine off. IE. INJ / RPM will drop to 0, but TPS will continue to vary depending on pedal position.

[Mighty Mira]

Originally Posted by MetroMPG

My car's ECU / sensors stay active if I stall the engine and leave the key in the "run" position. If your car is the same, you could stall it intentionally (while stopped) and then observe sensor inputs with the engine off. IE. INJ / RPM will drop to 0, but TPS will continue to vary depending on pedal position.

Thanks for the hint!

[Mighty Mira]

I made some more progress. I tested a few more pins at random, and got some interesting ones.

I think I found an injector signal. It pulses when I put my foot on the gas, frequency in proportion to rpm, and the pulse width gets longer when I floor it. When I take the foot off the gas, the pulses stop until the engine slows down to the point where the accelerator is, and then resume. That one is labeled "#10".

I think I found the rpm signal, or at least, something that measures rpm. It is labelled "IG".

And I think I found the TPS, which rises up and down when I pump the gas. It looks to be a straight voltage signal, although there appears to be some noise in that one. It is labelled "PIM".

If it's truly the case that these measure all those things, I have all the inputs that I need.

[MetroMPG]

Nice detective work, Mira...

Originally Posted by Mighty Mira

And I think I found the TPS, which rises up and down when I pump the gas. It looks to be a straight voltage signal, although there appears to be some noise in that one. It is labelled "PIM".

Rises & falls with the engine on, or off? The MAP is also a straight voltage signal on my car which varies (with noise) with throttle position - but only with the engine on. Engine off, it's a constant voltage.

Happy hunting...