Quote:
Originally Posted by Gaz64
Who tunes with a narrow band?
You can tune for any A/F ratio, stoich of 14.7:1, max power at 12.8-13.2:1, max economy at early 15s. You cannot do that with a narrow band.
Most cars these days have wide band O2 sensors ex factory. The ECM needs to know TRUE A/F ratio all the time. A narrow band cannot do that.
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Actually, no they don't.
The reaction time isn't as quick with a wideband, and to get the low emissions requirements they don't get used.
If you go to 15's, your NOx spikes. If you go to 12's, your CO and THCs spike. You can't have both and you need a rapid flux from slightly rich to slightly lean to ensure the cats are able to process all of the gasses correctly.
the ECM needs to know when things are slightly rich or slightly lean and to react back the other way. MAF sensors and VE tables control how much fuel you need, with a 14.7:1 as the required emissions target for just about every car.
The only vehicle that comes from a mass manufacturer that has a narrowband O2 sensor other than 14.7:1 is the old fuel injected rover motors that needed more fuel, and hence ran a 13.2:1 O2 sensor.
the narrow band tuning that I'm talking about is to get people through the IM240 test in NSW - I know you can get heaps powah with a wideband - this aint my first rodeo. What I'm trying to do is prevent people from pissing a load of money up the wall tuning a car for power without being able to pass the emissions test. Pass the emissions test, get the car registered. After that it's up to you.
Treeve