Quote:
Originally Posted by greg737
Yes, the Ecotrons kit O2 sensors are wide-band. You have to have wide-band O2 sensors if you want the ECU to be able to perform an autotune function.
And since wide-band O2 sensors are always heated, yes they are heated (narrow-band O2 sensors are not heated).
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Wrong. You need a wide band for tuning in general because a narrow band doesn't accurately read very far either direction of 14.7:1 air fuel ratio. You can tune with a narrow band, but it's not going to be very easy and will only be able to be used for idle to mid range, which is where you're normally at.
Also wrong because most normal cars have narrowband sensors and do somewhat auto tune over time. Usually the limit is somewhere around 10-20% max change from the original fuel map. There have been some known issues where computers will DETUNE an engine after modifying something though. My understanding is that you can gain more power from adding more advance than just playing with fuel alone. It's more dangerous, but you can see some better gains. Playing with the advance though, you're more prone to encounter preignition and running hotter so having pyrometers to detect when you start seeing a spike in EGTs is a good idea.
And wrong again, there are both heated and unheated narrow band O2 sensors. Heated ones are generally 4 wire, unheated are generally 1 wire. The advantage of the heated ones is they can start taking readings sooner to get the ecu using O2 sensor readings to make corrections.
While the motor is cold and when it's above 80% throttle, the computer only uses data from the tune to control the fuel to the motor, as well as IAT, coolant temp, eld, the advance will be adjusted to some extent based on the readings also. When the motor reaches normal operating temperature, and it's under 80% throttle, it takes in O2 sensor readings and attempts to adjust to get to 14.7:1 or whatever AFR you have it set to a spot on the fuel map. 14.7:1 is normal for idle to low load, though idle is acceptable to be between 13.5:1 to 15.5:1 or so. As load increases, you have to add more fuel to prevent preignition and engine damage. My understanding is basically that a leaner mix gives a little better throttle response, but a little richer gives more power. Too lean is dangerous, and too rich makes it slow and will just wash the oil off your cylinder walls. So you have to make that decision where to get the fuel dialed into and generally err on the side of caution and get it rich, then gradually lean it out to get it where you want it.
As said, you need a wide band to tune the richer portion because a narrow band isn't accurate very far off 14.7:1 AFR. When really pushing it, you need to be running richer to stay safe, 14.7 is not rich enough.
I'm no expert on tuning EFI, but I've been playing with Hondata S300's SManager and I've kept a boosted motor running more than a year tuning it myself. I have issues keeping open and closed loop straight, but I have the general idea down.