the motec m400 should be able (if it can understand the trigger wheel, and how many injectors we run?) to run the renesis. this is around the $3000 .au mark (with Drive by wire) so it changes the megasquirt argument a bit.

 

Are the Star Mazda teams running Motec or the OEM Denso ECU?

 

It can read the stock trigger wheel. But it is still FAR more than $200 and I don't already have a Motec. I have a Megasquirt. The story is still the same. I would be more than happy to use a Motec as they are fine units and I encourage anyone else to try. Money is money though so I'll let others worry about it.

 

Motec 400

Is there any way to modify timing in these engines? I wanna go up in boost but my car pings when i do that...

 

Yes. The trigger wheel conversation above relates to timing. We are going to prove we can manage fuel first, then move on to timing.

 

How are the (2) Primary 2 injectors controlled? It was my understanding that all 3 pairs of injectors have seperate control signals with the stock ECU. The Motech 400 only has 4 injector outputs. So are the Star Mazda engines modified to fire both primaries (per rotor) with one signal?

 

I am not sure about this topic too much but no, the engines are exactly the same.

 

For starters, we are going to do just this, wire the primarys up together, and the secondaries as a seperate output. If you look at the injector duty cycles, this should work fine. As we get more comofrtable with the MS, we may try to rig them up as 3 standalone sets.

 

Don't wire the primaries together.
Wire the primary 1 and secondaries together. Leave the primary 1 on their own channel.
You will have a hard time making the thing idle the other way.

 

Your right, sorry thats what I meant.

 

We can't run them as 3 individual sets with MS. The primaries located in the center engine housing will be on channel 1. The other 4 that are located in the intake runners will be channel 2. Channel 2 will come online somewhere around 3500 rpm or wherever I tell them to.

 

I got the haness wired up for testing. Hopefully in the next day or so I will get a chance to plug it into Alan's car. What I am looking for at this point is not full control but rather verification that I am getting all of the vital signs read. The coolant and air temperature sensors are wired in as is the narrow band 02 sensor, the tps trigger, and the rpm signal. If Megasquirt can read all of these with no problem, the next step is to wire in the fuel injectors and try to start it up. Wiring the injectors in is an easy thing to do as I already have the wires laid out. Just need to get the soldering gun out. If all of this works well, it's oof to the ignition system. Stay tuned...

 

Hooked up the Megasquirt to the RX-8 for the first time today. We just wanted to make sure we could read all of the sensors. We have a working coolant temp, air temp control, know where to tap into for manifold vacuum (that one is simple), and have an rpm signal. We had a hard time today with the tps signal. The wire we thought would work, didn't. At least not properly. I'm a bit confused because we tried many combinations and couldn't make one work right. The signal wire we originally tapped into gave us the voltage range we needed as the throttle was opened and closed but that's all it did. It didn't do it linearly. If you suddenly floored it, the MS would read it properly. If you just casually got on the throttle like you were just driving normal, nothing would register. When the voltage does change for a certain throttle level, it only does it briefly and then settles back down to it's base number, even if you still hold the throttle there. It's very strange. Still working on the throttle issue so until that is resolved I can't try hooking up the fuel injectors. The new wires are ready to go. They just need to be tapped into.

We also ran into an issue with the 02 sensor. More specifically the narrow band one. That's the one I want to tap into to determine how the car will run in closed loop. The RX-8 narrow band 02 sensor has a different switchover voltage than the average narrowband. I can't quite figure that one out. Supposedly I can account for this in Megasquirt but was unsuccessful when I tried. Since I plan on tuning the lower end of the map for economy there really isn't a need for a closed loop mode. Because of this I don't really need the 02 sensor anyways. Mazsport doesn't use closed loop either for the same reason. I may just skip this entirely for now. Later on we will tap into a new added on wideband 02 sensor and control the engine based on a/f ratio by having it self adjust.

The next thing to take care of is the tps sensor. When that is worked out, the injectors will get wired in and we will fire the car up for the first time without the stock ecu controlling fuel. We have a hunch that we will be able to control fuel at will and the car will still run better than stock. We will play with that for a while. An ignition solution is still in the works but we'll fully worry about that when we get there.

More to come...

 

RG: Don't know if this helps, but AFAIK, the throttle pedal turns two pots. The ECU reads both, and cancels the difference between them (noise canceling). It sounds like maybe you were reading the difference between the pots?? That would make sense because the two pots will respond differently in their range of motion, but by using two, the differences in manufacturing should cancel out.

If you were reading the TPS (as opposed to the TPP), I believe it only increases in voltage until the servo has moved the butterfly to the right position. Once it moves enough, the TPS drops to baseline (I think).

http://www.auto-solve.com/etc.htm

 

There are 2 different circuits. We know that. The problem is that the Megasquirt needs to see a certain voltage for a certain throttle plate opening. We did find a wire that looked good in MS but when Alan stepped on the gas nothing happened. The voltage only changed when he made quick sudden throttle adjustments. It should change any time your foot moves. The other circuit we found didn't have a wide enough range and no matter what I did the ecu thought the car was always about 25% throttle. Can't have that. The most frustrating thing is that when it does detect the throttle opening and actually does register a voltage reading, it only does so as long as the motor is moving. Once the throttlebody gets to it's spot, the signal goes away. This won't work for us. Still working on a solution. We could have missed something too. This is the only thing stopping us from firing it up with fuel being controlled by MS.

 

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This makes sense as the wire you are into probably is like an accelorator pump. This would give extra fuel for a second then back off like you discribe.
Were you opening the throttle by hand or using the pedal?

 

Why not use the throttle pedal position instead of TPS?

 

Why not add a new TPS to the shaft?

 

This is the wire for the E-manage TPS connection......might help

 

Both components of the TBW system have duel outputs.

The pedal reads low to high on both feedbacks but one should always be .5 vdc higher than the other.

The two TPS signals read opposite of each other.

The pattern should be the same for the pedal signals.

The pattern looks like a X at the throttle body.


Sorry I missed the call...I tried to call you back... :o

 

we tried to use the throttle pedal postion to no avail.

Richard, when you say add it to the shaft, you mean add another sensor to the throttle bodyat the motor?

I wonder if there is a way to take these two signals and combine them into one with some sort of circuit switch. any thoughts on this from the group?

 

we tried this wire with no luck, this is the one that gave us no part throttle response, but if you floored it it would register.

 

Yes, just pick up a GM TPS or ford or whatever you have hanging around. Add it to the shaft maybe on the other side of the one that's there now.
Or maybe the shaft goes through and you can pick it up.

Why not test it with some linkage and remote mount?

 

It is strange that the E-manage will PU the signal but the Megasquirt will not? It is a straight voltage output on that wire AFAIK?? about 1-4V ?

 

there is voltage there, the one you mentioned goes from about .4 - 4.093?? volts and then the second TPS reads about 1.0-4.3xx volts. I would have thought that the one you mentioned would have worked too.

Maybe we need to revisit that wire again and check our settings.