The "let's brainstorm how to make a piggyback work" thread

[Loren]

Originally Posted by PK198105

What could be tried , is to take an ecu from a bigger 4 and wire it properly. If all inputs and outputs are correctly wired we can achieve wider operational range.

We should petition Denso/Toyota to open the ECU to mods without sacrificing their trade secrets.

Wouldn't work, PK.

The ECU is still going to take the feedback from the O2 sensor and tweak the AFR to stoich. It's what they do.

Now, what I don't know is... what does the Yaris do when you go WOT? Because it's an economy car, is it still trying to keep the AFR at stoich? Does it have a WBO2 stock so that it can run lean? If so, does it use that to run richer at WOT?

Most cars that I've seen that use NBO2 simply go open loop at WOT, disregarding the O2 signal and running from a map. This is surely what the Yaris is doing now that I think about it, because we can see with the ScanGauge that the car goes Open Loop at WOT.

Soooo... if we're talking about making the car run a little richer at part throttle and during cruise, the WBO2 "cheat" should work. But, it's not going to do a thing for full-throttle acceleration.

To get more fuel at WOT, you simply need to fit larger injectors and/or increase fuel pressure. What the ECU is doing at WOT is looking at RPM, air temp and air flow and looking up a fuel requirement in a table. That translates to the pulses that are sent to the fuel injectors. The ECU assumes that the stock injectors are present and flowing within spec and that the fuel pressure is within spec. If you fit larger injectors, you'll flow more fuel, but you could run out of fuel pressure if you go too large. If you raise the fuel pressure, you'll also flow more fuel.

That, coupled with a timing controller (doesn't somebody make one of those for this car?) should take care of your needs... shouldn't it?

PK, think like a large corporation. What possible benefit is there for them to put any of their resources into releasing information about their ECU? Ain't gonna happen. They want performance-minded people to spend their money buying a sportier Toyota, not buying performance parts for a Yaris.