ecktt

This is what I understand from what I've read.

A narrow band that comes stock is excellent at measuring 14.7 afr. Everything else is either to rich or to lean.
A Wideband such as the Innovate LC-1 can measure...well...a wide range of AFRs. When Tuning you have to use a wideband.

My questions are:
1. If my and other Evos come with a stock map with AFRs ranging from 14.7 to 9s, how does the stock narrow band handle that?

2. Is it possible to use a wideband as the primary sensor feed back correct values (other than 14.7) to the stock ECU?

RoadSpike

iTrader: (5)

1) Above a certain TPS and load the car's ECU just ignores the narrow band sensor and simply assumes the correct fueling off the MAF sensor, RPM, and temp.

2) Yes but it requires either a narrow band simulator from a wideband controller such as with zeitronix or a modification to the ECU to accept input from a wideband opposed to the normal narrow band input such as MrFred's control routine which i believe still requires a wideband controller.

TouringBubble

iTrader: (2)

To elaborate a little on point #1 above in relation to your 2nd question ...

The stock ECU doesn't care about values other than 14.7-ish. As RoadSpike said, it just ignores the sensor in open loop mode (pretty much any time you're in boost).

The mod from Mrfred sends a wideband signal to the ECU and allows for closed loop control across the entire load range I believe, so it would be useful in that circumstance.

But, in short, when at wide open throttle on the stock ECU, the limited resolution of the narrowband sensor is irrelevant.