Lean ??

[phoenix99]

Hi, I've plugged my wideband on the driver side exhaust and the reading is around 15.5 - 14.5 at idle, 15.0 14.3 acceleration and 14.7 13.5 at wot
I've a mac prochamber and no muffler... I've read somewhere that a no muffler setup can cause a lean reading but is it true? Should I buy a set of muffler?
I want to spray wet nitrous but i'm a bit scared to spray if it's lean before spraying...

Thanks

 

[Stark77]

if you have a handheld tuner you should be able to bump up your A/F ratio 3% or 4%

 

[bhuff30]

That seems a bit lean all over. Cruise should hold a pretty steady 14.7. On my stock 97, on a WOT run in 2nd or 3rd, it is around 13.5:1 till 3500, then starts dropping to 12.5ish:1 by 5500. Mufflers should make no appriciable difference in AF ratio.
Try cleaning your mass air meter. When they are dirty or coated in oil, they will read low, causing a lean condition.
As for spraying, you can change the jets until you are happy with the AF ratio. If you think it is too lean, then just put a size bigger fuel jet in. You can buy jets in increments of .001 or something, so you can certainly get the AFs where you want while spraying.

 

[98COBRA281]

yeah that seems rely lean, at WOT 3500-6k, my a/f ratio pretty much flat lines at 11.7