2ZR Turbo Yaris

[06YarisRS]

Fuel Trims and Toyota 02 Sensors and some updates

If found an interesting article on Toyota oxygen sensors. Most of the reading I've done online suggests that downstream 02 sensors are not related to fuel trims, but it seems that some Toyotas do infact collect data from the post-cat sensor which may influence fuel trims. From paragraph 22: "Since Toyota allows the rear O2 sensor a surprisingly large authority over fuel trim, you’ll want to test it carefully as well. (Many generic interfaces call out the rear O2 sensor’s contribution to fuel trim separately under a heading such as FTB1S2.)"

https://www.motor.com/magazine-summa...ta-af-sensors/

Right now, my downstream sensor is just hanging beside my downpipe.

As mentioned my fuel trims are out of whack. Speaking with the turbokits tech support, the issues should be resolved when the F/IC is hooked up. There is a distinct difference in how the stock MAF sensor is mounted vs in the kit charge piping. In the stock application, the intake pipe narrows and appears to direct all of the air through the sensor. In the kit, the MAF sits in the middle of the free-flowing piping. The MAF clamp feature of the F/IC caps the voltage to around 5 volts which keeps the ECU from going snaky with higher voltage inputs.

Pic of the MAF housing in stock airbox:



I'm continuing to try to figure out all possible causes of my high trims - or maybe more appropriately, what factors could contribute to a lean condition. With the valve cover vented to atmosphere, it draws fresh air into the crankcase as the PCV vacuums out the combustion byproducts. Because this new air from the valve cover breather is then drawn into the manifold via the PCV system, it could be considered unmetered air. I have been receiving a number of different theories and suggestions from different sources. One guy says that I should be fine with my current setup as the crankcase has nothing to do with the vacuum system. Another source says that introducing air directly into the crankcase via the valve cover breather will definitely introduce unmetered air and make the car run lean. The guy who will be tuning my car says to remove (block off) the PCV system at the manifold and PCV valve (at block) and run my catch can with a breather on it on the valve cover breather. Yet another source suggests, blocking the manifold PCV intake, removing the PCV and putting a breather on that along with my valve cover breather. Lots of suggestions!

On another note, I have been advised to not attempt to have the F/IC control the VVTi and with regard to timing, all that's needed is the crank sensor at the relatively low boost that this kit will have.

I will also be changing my source of power to the F/IC from my original proposed pin 28 on connector A21 to the #1 EFI switched/fused circuit.