Say hello to the Mighty Mira!

[Mighty Mira]

Originally Posted by MetroMPG

FWD cars have the diff built in to the transmission. Where the axles come out, that's the diff.

Your options are: taller tires and/or wheels & tires, or a different transmission.

Redline: to give you a ballpark - my 993 cc Suzuki 3-cyl (6 valves) rev limiter is 7K RPM, the Honda Beat 660 cc engine has a 7200 RPM cutoff, or a 9k RPM cutoff, depending on the model.

Ahah! So even though the engine sounds like it's going to explode any minute, there is actually no problem! Cool...

I'd still like to get it down to something at 3k or below for cruising.

As for the tyres, probably best to assess things as a wheel/transmission system. Since we may need to change both, and the options probably don't lie along a continuum, best to see what will give best combination of both rolling resistance and gearing.

Thanks for the help!

[Mighty Mira]

Well, I just found the throttle positioning sensor (TPS), although I have not yet been able to track it back to the ECU. I basically just followed the throttle wire to the engine, where conveniently it sits somewhere along the intake line.

I opened the housing, and saw that the bottom two wires (a white and a yellow with green stripe) connect when the throttle is pressed. This obviously sends the idle signal, something I found on the ECU, marked "IDL".

The other wire must give the position. It is yellow and red.

Edit: Hmmm. Maybe it isn't a potentiometer.

I had another look. It seems that the upper is permanently on +5 Volts, the lower is permanently on ground, and the middle is at 0V at idle and +5 Volts at WOT.

That's pretty damn lame, if I am correct. It means that I can't get a look at where the throttle is without grafting on some sort of aftermarket TPS. Damnit. I wonder why the engine doesn't need to know where exactly the throttle is?

[Mighty Mira]

google gave me this.

Polyxtroy: Cannot, missing a proper throttle sensor on all Mira's engine. Mira's throttle sensor operates on on/off setting only. Whereby a proper one's gives the ecu a range of trottle positions. E manage fuel maps are based on rpm/throttle positions/map sensor.. therefore rather untuneable on a L series ecu.. (By experience)

equin0x:i believe polyxtroy have experience with e-manage before he throw it away and replace with something else. L200's TPS is based on logic on/off only (either 5v or 0v)

John Siew: When your mechanic tells you that Daihatsu Mira L200 does not have a throttle sensor hence air/fuel tuning is not possible, they're probably crapping or they're not familiar with it.

The fact is..

The Daihatsu Mira DOES have a TPS (Throttle Position Sensor) but the TPS on a Mira is only an On/Off TPS (same like what we've studied in logic, 1 or 0). Meaning to say, 0 Volts when the throttle is off and 5 Volts when the throttle is on; even if you just touched it a tiny bit.

On a Potentiometered TPS has on/off feature as the Mira. Upon a little bit more throttle after "on", the voltage goes back to 0 Volts. Then as you progressively step on more throttle till full throttle, you should get about 4.5volts to 5volts. So wiring the throttle function in your Mira doesnt do anything as it does not have the progression of the potentiometer.

However, technically if you can fit a potentiometer type TPS to your L200 and still having the On/Off side hooked up to the ECU, you might be able to get the piggy back air/fuel controller to work, but you would probably have to replace the entire throttle body.


The disadvantage of this set up is that, if your vehicle is tuned for 14psi (1kpa or 1.0 bar) of boost, running less boost might be a little richer than required. So to be honest, not much of a big deal as fitting a potentiometer type TPS, you will get the air/fuel tuning to work, but the ECU would still have nothing to do with it.

To summarise that, myth said that air/fuel tuning is not possible on a L200 but the actual fact is, it is possible to be done! Apexi S-AFC is a good economical start. The EF-JL management system does not run a TPS and therefore, you can't tune your low throttle setting. However you can tune the high throttle at full wide open throttle, which may make your mixtures slightly richer if you are running lower boost than what it is tuned for.

So basically, looks like if I want TPS I'd better attach my own aftermarket one.

That saved me a lot of work trying to find a TPS that wasn't there. In the meantime, I should be able to build myself a little FE meter or a coastdown tester.

[Mighty Mira]

Injector waveform:



This $20 1960s vintage scope is easily the best investment in test equipment I have ever made. Here it is sitting in my car plugged in from the inverter.

[SVOboy]

Hmm, smack on a honda tps, same upper/lower limits but with a continual blah blah.Do you have a MAF sensor?

[The Toecutter]

This $20 1960s vintage scope is easily the best investment in test equipment I have ever made. Here it is sitting in my car plugged in from the inverter.

That is one phat ****ing oscilloscope.

[Mighty Mira]

Originally Posted by The Toecutter

That is one phat ****ing oscilloscope.

Thank you. I knew another EE would appreciate it, especially one who actually was interested in that sort of stuff prior to getting into college. I wouldn't worry about getting a job post college... it's always the guys who actually do this stuff for fun who always end up readily employed.

It's funny, this is the first non-software EE stuff I've done since college, and I'm enjoying it. All 10Mhz of bandwidth, too! Should be fine for an automotive application.

I wish I had a pic of the banana plug to BNC connector I soldered up. Unfortunately this is the only photo I took with most of the scope in the picture.

The scope cost something like $21 AUD and I had to spend a couple bucks for the connectors and $30 for a new probe. I tried adjusting the probe, but I think it just has some residual waveforms showing through from the inverter in the car. Anyway, it's close enough for what I want to do. Ebay rocks.

To put it in perspective, I would have paid $128 for a new 10Mhz scope with about a third the visual area. Of course, this does take 3 minutes to warm up, but them's the breaks. But it does have excellent triggering, the other scope I bought from the same guy is 20Mhz, dual trace, but does not have as good a triggering. Maybe it's just my incompetence though. (I got the 20Mhz dual trace for $50 AUD.)

[Mighty Mira]

Originally Posted by SVOboy

Do you have a MAF sensor?

Pretty sure I do. I have a sensor that looks almost like the throttle, but after the rpm catches up with the throttle, the line backs down. Why?

Hmm, smack on a honda tps, same upper/lower limits but with a continual blah blah.

Cool! I'll have to have a look. I am not really sure where I would get one from, any ideas? Should I expect it to just bolt on?

[SVOboy]

I have no idea about it bolting on, I'd have to see a comparison. Matt has some, I'm sure.

Anyway, the MAF would prolly explain the crappy tps, since the MAF will know well how much air is coming into the engine, so*shrug*

[Mighty Mira]

Originally Posted by SVOboy

I have no idea about it bolting on, I'd have to see a comparison. Matt has some, I'm sure.

Anyway, the MAF would prolly explain the crappy tps, since the MAF will know well how much air is coming into the engine, so*shrug*

Hmmm. Does MAF * RPM = TPS? If so, I could simulate a TPS signal.