When do you need a Wideband A/F ratio kit?

bloopbloob · Oct 28, 2007

Like the title says, when do you need a Wideband A/F ratio kit? i know a lot of people are running them.... what does it do exactly? i assume you'd need a afpr also, to be able to use the information...?

RS200 · Oct 28, 2007

It's a tuning tool, very useful for forced induction engines. Goes hand in hand with AFPR or FMU.

Mr. Rustypwnz · Oct 28, 2007

you have no need for one, it tells you your a/f ratio, on a large band.

RS200 · Oct 28, 2007

slow95gt said:
you have no need for one, it tells you your a/f ratio, on a large band.

Say that when your pistons look like metallic potatoes. A wideband tells you your A/F ratio (obviously). Then you use the information and adjust fuel pressure, or delivery accordingly. If you're driving a turbocharged or big shot nitrous injected car completely untuned, it's only a matter of time before you destroy your engine.

Mr. Rustypwnz · Oct 28, 2007

yes, I know but look at his combo and truthfully tell me he needs a wideband....

I also know he was just asking, but I was just saying that he doesnt need one at this point, maybe if he added a blower and better heads and cam, yes but right now, no.

now im going to leave this thread before digging myself in a bigger hole!!

strtrcr50 · Oct 29, 2007

You need a wideband when you have the ability to actually change the tune. By playing with the fpr, the computer will just bring it back to where it wants it anyway.

UnderdogGN · Oct 29, 2007

My experience- i have a h/c/i car with 24# injectors. At first i set the fuel pressure by searching on here (i think i was told like 39#'s). I then bought a wideband and hooked it up at went WOT and it was extremely lean! 14.3 to 1. I then had to add 4 or 5 more pounds of fuel pressure to get it to read at 12.8:1 where it should be.
What im saying is the wideband O2 is one of the best tools you can use. So just by reading on here what usually works can be wrong as it was in my case. I think they are well worth it, mine was $300 brand new.

millhouse · Oct 29, 2007

UnderdogGN said:
My experience- i have a h/c/i car with 24# injectors. At first i set the fuel pressure by searching on here (i think i was told like 39#'s). I then bought a wideband and hooked it up at went WOT and it was extremely lean! 14.3 to 1. I then had to add 4 or 5 more pounds of fuel pressure to get it to read at 12.8:1 where it should be.
What im saying is the wideband O2 is one of the best tools you can use. So just by reading on here what usually works can be wrong as it was in my case. I think they are well worth it, mine was $300 brand new.

The problem is, while adjusting the fuel pressure for open loop (WOT) works temporarily…it is usually a temporary fix. After upping the fuel pressure you likely threw off your closed loop fuel trim which will eventually correct itself to get back to stoich (14.7:1). These same tables are used as the base for WOT open loop operation, so it will effectively revert back to the lean conditions you previously were seeing. Adjusting fuel pressure in an attempt to get back to stoich during closed loop operation is the only real adjustment you can do without either having a custom tune to go with it…or run in open loop all the time.

In the end, a wideband is only as good as the means to tune. Sure…it can tell you right now if your running safe AFR's, but without a means to effectively tune…many would consider it a waste.

UnderdogGN · Oct 29, 2007

hmm...my A/F ratio has stayed where i set it after i upped the fuel pressure so far. I understand what your saying though. How long do you think it takes for the computer to change it back?
thanks for the info

millhouse · Oct 29, 2007

UnderdogGN said:
hmm...my A/F ratio has stayed where i set it after i upped the fuel pressure so far. I understand what your saying though. How long do you think it takes for the computer to change it back?
thanks for the info

From my understanding, the more you drive it...the quicker it learns. It could take a week to a month or more, depending on you habbits.

On a side note, what is your idle and light cruise AFR's?

ninety15.0 · Oct 29, 2007

I think millhouse has a good point on one hand...but not on another. The computer will make adjustments to get the AFR back to stoich(sh) in closed loop...But it can only adjust so far. If you look at how you injector flow rate is influenced by fuel pressure you can get a better understanding on the subject. Flow rate is increased/decreased dramatically with changes in FP. This will effect both OL and CL operation. If you make too drastic a change to the FP the computer will not be able to bring you back to stoich.

So really you both may be right its just that underdogn may have adjusted the FP out of the range that the computer can compensate. while your WOT AFR may be ok now...you may be running rich under your CL operation and not seeing any changes b/c the computer has made all the leaning adjustments it can. So you have a safe afr..but may be leaving some fuel economy and CL power on the table b/c of it!

Just some food for thought. OP you dont need a wideband.

UnderdogGN · Oct 29, 2007

hmm not sure on cruise or idle because my car has been sitting at the trans shop for the past month and i cant remember. What is a good A/F ratio for idle cruise?

I agree that i am probably suffering gas milage with the fuel pressure i run, but im not too concerned about that because its not my DD. The whole reason i bought the wideband was to make sure i have a safe WOT A/F ratio on nitrous. Although i havent tuned it yet with the spray because i wanted to get it within reason N/A first. Anyway i agree you dont need a wideband until you have a power adder.

millhouse · Oct 29, 2007

UnderdogGN said:
hmm not sure on cruise or idle because my car has been sitting at the trans shop for the past month and i cant remember. What is a good A/F ratio for idle cruise?

I agree that i am probably suffering gas milage with the fuel pressure i run, but im not too concerned about that because its not my DD. The whole reason i bought the wideband was to make sure i have a safe WOT A/F ratio on nitrous. Although i havent tuned it yet with the spray because i wanted to get it within reason N/A first. Anyway i agree you dont need a wideband until you have a power adder.

The AFR at idle and cruise should be 14.7:1. If it's not, the computer will continuously adjust the base trim in attempt to get to it...within I believe 12.5%. Once you've adjusted the fuel pressure so your outside of that range, the computer will no longer compensate. To get outside of that range however, typically you'll get very rich idle and cruise AFR's.

When do you need a Wideband A/F ratio kit?

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