does anyone know what each of the two o2 sensors do? does the first one or the second one pull a/f readings? i have an exhaust leak before my second o2 and i am wondering if that could be screwing up my a/f ratios.

 

From what I've been reading, I'm 99% sure it works like this:

1st O2: before the 1st cat, takes the A/F readings

2nd O2: before 2nd cat, compares reading with 1st O2 to make sure 1st Cat is working properly

Thats why when you install a header and remove the first cat, your A/F is fine and your CEL comes on. When 1st O2 reading and the 2nd O2 reading are the same, it makes the computer think your 1st Cat isn't working (well, it's not, cause its not there and sitting in your garage). If you add a Mil eliminator to the 2nd O2, you change the voltage output to the computer and "trick" it into think the 1st cat is working properly.

So if your leak is after the 1st O2, it shouldn't mess you A/F.

 

laxwax pretty much wrapped it up in a nut shell!

 

Is anyone aware of someone who sells just the O2 simulator (not a Cat delete and eliminator kit)??

 

get a wideband o2 sensor.. the only way to tru tune your a/f rations.. i need to get mine this week.. u can get them off ebay for around 300 bucks