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

[eTiMaGo]

OK, here's my first draft:

Marcell,

Thanks very much for your enthusiasm!

The interest in tuning our cars' fueling is primarily for use with turbo/supercharger systems. But, if there s enough flexibility and results, I am sure may would be interested in tuning for better fuel economy too.

I will quickly outline the progress and attempts at working with piggybacks fuel management systems on various US Yarii.

Some years back there was a company, Zero Point Industries, which has since gone out of business, offering a turbo kit for the car, and using an e-manage unit for fuel management. They were unable to overcome the car's closed-loop logic for tuning, and their solution was to have the car in a permanent CEL condition, where the fueling runs in an open loop, and the e-manage can have control over it. As you know, this is an extremely crude approach!

Other members of our community have tried using AEM's FIC device which is supposed to work very well, but have had many problems, usually in closed-loop mode when then ECU is fighting hard to keep the AFR in stoich. I do not have more specific details at the moment but I can ask them to provide more information if you need.

On the other hand, we have a handful of members who are using a supercharger kit manufactured by Blitz, that comes with its own fuel management piggyback unit. Not a lot is known about its exact operation, but those members who have dyno'ed their car, or have a wideband O2 sensor, have found that it is still running rather lean, even at WOT when the car is supposed to run in open loop mode.

Now, one of these members is moving to a full standalone management system, but this is really out of the skill and budget of most enthusiasts who just want a reliable way to add 30-50 horsepower to their car.

We collectively have done a lot of research into the way Toyota set up the ECU to monitor the various sensors (MAF, IAT, AF, O2) to calculate the correct injector duty cycle, and it really is a rather tight-knit system, which is great if you do not intend to tweak anything, but too smart for our own good! We have access to rather detailed technical reference (repair/service manuals) describing all of this, so please let me know if you would like a copy. Alternatively, you can check the "brainstorming" thread in our forum:

http://www.yarisworld.com/forums/showthread.php?t=15350

Feel free to add/remove/modify