wide band vs narrow band what's what?

[omarestrada599]

what's the difference between them? Is one better than the other? Does brand matter? Do they tap into the factory O2 sensor or they need a new O2 hookup? my car was at 13.5 AFR during the dynotune is this good?

[granatl]

Narrow band (the ones delivered with most cars) can only accurately measure a narrow band around stoichiometric (gas is 14.7:1, etc.) So, (IDK exactly), but let's say between 14:1 and 15:1.

Wide band (WB) can measure most of the spectrum, often as low as 7.5:1 (VERY rich) to 20:1 (VERY lean)

Although they make systems that will convert WB to narrow, most people instead just add a WB into the exhaust w/o tampering with the factory setup.

The richness of PE depends on your setup (i.e. a turbo vs. N/A vs. ...). 13.5 in Power Enrichment is a bit too lean. That number should be a bit richer and closer to 12.5 AFR. (There is some variance, car to car, sensor to sensor). And your signature talks about E85, so that's way lean (using the gas AFR to describe E85).

You will hear us talk about Lambda. That's preferred, especially when you switch to other fuels. Far less confusing than "E85 measured on the gas AFR."

[granatl]

To elaborate on my final point about lambda:
Lambda 1.0 is stoich, regardless of the fuel, blend of fuel, ... that is, it's the balanced mix of air and fuel, chemically speaking
WB sensors are REALLY lambda sensors. The electronics in the WB then multiplies the lambda value against the selected fuel type's AFR scale. So, in the gas scale, 1 lambda x 14.7 = 14.7 AFR
So, re-iterating, while the car is warmed up and idling or driving under light conditions, it'll be 1.0 lambda, regardless of the fuel you're using (provided your car is operating correctly).

When you go into Power Enrichment (PE), the car commands more fuel to help cool the cylinder temperatures and reduce the chance of pre-ignition. For me, with a single turbo, I try to target .75 lambda on e50-e85. When I use more gas (say e30), I want to say I target slightly leaner, like .78 lambda. (I think you can see the value of lambda now, since each mix of ethanol and gas would create a new AFR scale and too much of a PITA to calculate).

[Badbubba]

Go with a wideband that displays lambda. With e85, the ethanol content can vary. To get afr, You would need to have the % ethonal value displayed from your flex fuel sensor. Then you can figure out the stoichy of what blend you in the tank, 14.7 for straight gas, 9 for ethanol. You would enter that stoichy value into the wideband. Not all widebands have the ability to enter a custom stoichiometric value. If not, then the wideband will most likely have a default of 14.7, straight gas. And you would need to apply an offset depending on your blend to your displayed afr value from the wideband. Now that you have the afr value, you can decide if it's where you want it. All this can change on your next fill up. So just go lambda. At WOT, you'll be around .85 lambda for naturally aspirated and .75 to .78 for boosted (turbo, supercharger, N2O), regardless of fuel blend, generally speaking. Around 1 for normal driving.
Have a bung welded into your long tubes at the collector area so you can install the sensor. About the 1 to 2 o'clock position, looking from the back to the front on the driver's side. The wideband will be a stand alone device. If 13.5 afr was at WOT with gasoline, then it is on the lean side. If it was on e85, then way lean. Note, most gas contains 10% ethonal, so gasoline is actually e10. Also, using e85 requires about 30% more fuel. Be certain that your fuel pump and injectors, duty cycle, have that headroom for the extra capacity. If not, upgrades for fueling will be needed.

[JooktheSnooke]

i too had questions about this. so is this something that more beneficial for someone going e85? if i was to just stay on standard pump fuel (93) would all the AFR just be taken care of by the tuner? taking my car for a tune in the spring

[Badbubba]

Originally Posted by JooktheSnooke

i too had questions about this. so is this something that more beneficial for someone going e85? if i was to just stay on standard pump fuel (93) would all the AFR just be taken care of by the tuner? taking my car for a tune in the spring

At our level, the wide band supplies no feed back to the tune while driving. It is just a gauge and something you can monitor. If you do a dyno tune, the tuner will use their own and stick it in the tail pipe. If you do a remote tune, it may be helpful to the tuner, but not necessary. It will give you some piece of mind by knowing the value and if it changes, you will need to find out why. Could just be the sensor aging. No, it can benefit you no matter what fuel you use by keeping you informed. Yes, the tuner will tune the car and therefore your afr will be adjusted. Stoichy for straight gas is an afr value of 14.7, or a lambda value of 1. Stoichy for E10, which gas may contain upto 10% ethanol, is 14.1, or a lambda of 1. Stoichy for E85 is an afr value of about 9.7, or a lamda of 1. E100 is 9, lambda of 1. A wideband is truly a lamda gauge, that can display lambda or afr. It uses the lambda value, multiplies it by the programmed value or default stoichy value in the wide band and displays it as an afr. WOT NA motor will be about .85 lambda, no matter what fuel. Afr for straight gas would be .85(lambda)x14.7(stoichy)= 12.5. For E10, .85(lambda)x14.1(stoichy) = 12. For E85, .85(lambda)x9.7(stoichy)= 8.2. E85 can vary from E50 to E85, winter/summer blends. Even 93 octane gas can vary from 0 ethanol, upto 10%. So, your stoichy value changes. If you do not input the correct stoichy into your wideband for your base multiplier, your afr value is meaningles. BUT, your lambda value is golden from the wideband. Because lambda is lambda, regardless of fuel. In the Camaro, I run 93 octane. Which is usually has 10% ethanol added when I buy it. The Autometer wide band has a programmable stoichiometric value. I use 14.1, the value for E10. But it doesn't matter, because I display lambda as the value and look for .85 at wot. Unless using N20, then a lambda value of .78. In the Subaru STI, I run E85, which varies and I vary the blend too. I use an AEM wideband that does not have a programmable stoichiometric input, just a list of predefined values. But I don't care, because I display lambda on that meter. Which is .78 because it is a turbo. The added flex fuel sensor monitors the ethanol content and adjusts the parameters in the tune.