Ok, I have a FJO wideband(a real wideband). I was kindof lazy so it is just in one of the rear o2 sensor bungs, but here is my questions.

Won't my readings be leaner because it is after the cats?

Also, I had been using a moddified air box, and at WOT I was seeing about 11.1~11.4 AF(top of gear) Now I just installed a cone filter with a homemade fan wash sheild, and I am reading 10.2~10.4 AF(top of gear) and it's even a little cooler outside. Does this seem logical?

 

Nobody knows/has an opinion

 

I don't have an answer, because I am still learning about this a/f stuff, but a/f levels in the low 10's isn't that running really lean and hot? Or is that an acceptable level???

My dyno runs from low 15's out of the hole to level off in the 12.1 range - I know that is rich, but safe with my KB.

D-Day

 

The higher the leaner. The leaner the hotter. I think the computer will try to get the a/f at 14.7 cruising and at idle. You want it to go rich during WOT to cool the cylinder and have plenty of fuel to burn. Not too rich because you will lose power and not to lean because you'll damage the engine. I think most people want the air fuel at WOT to be low 12's and high 11's.

 

easterisland, thanks - that certainly clears up my miss understanding! I was heading in the wrong direction.


D-Day

 

Generaly, regarding Air/Fuel ratios:

Air to Fuel
13+ - 1 = lean and not so safe.
12 - 1 = on the edge with good power.
11 - 1 = rich but safe and a little less power.
10- - 1 = rich and Opec is smiling.

NoSurprise

 

What about the readings after the factory cats? Won't they read leaner than actual?

 

I would agree that a reading after the factory cats would be leaner as well. The purpose of the cats is to help eliminate excess fuel and harmful engine gasses and convert those to carbon dioxide and water. I would definitely take the reading before the first convertor. On a side note, how do you like your FJO? I've been looking to purchase one for a while but haven't seen too many with them. Most people just buy a chip and dyno once or twice and are happy.

 

I love my FJO; with it hooked up I ALWAYS know what is going on. Things can change/happen after a dyno tune. It's a little expensive, but if you think about what a motor would cost. I think easterisland, and 99svtlightning also have them.

 

hook it up before the cats....it will show leaner after.

 

Hum; So if I am showing low 10's AF after both factory cats then I am running WAY rich.