A/F Ratio Lean?

[97gsxtreme]

I recently installed an A/F Ratio guage on my 97 Eclipse Gsx. I went to test it and when my car shifts to 3rd gear (Auto) at WOT mygauge drops from the Rich range to the Lean range. My Cars mods are 1G BOV, Dejon Tool UICP, 3" RSR Downpipe, 2.5 Cat Back, Intake and MBC set at 13 PSI. I have searched and all the things i have read says that 15 psi is limit on stock fuel system. Any help would be appriciated.

 

[97gsxtreme]

I am also still on the stock T-25

 

[91TSi FWD]

Check for any intake leaks/cracked hoses, you could have unmeasured air entering your engine, though it would have to be a big leak to make much difference.

 

[GSntncT]

Does your car misfire badly when accelerating? If not, look at your front 02 sensor. I had the same problem with my car. You can foul a sensor just like you can foul spark plugs.

 

[civic619]

how can you tell if your 02 sensor is fouled? and what causes it to foul up?

 

[GSntncT]

Originally posted by civic619
how can you tell if your 02 sensor is fouled? and what causes it to foul up?

When I figured it out, it was a process of elimination scenario. I think I just happened to be lucky. I can't give you a full explanation has to exactly how they can foul up, I just now know they can. The only thing I can tell you is to just take of the 02 sensor, and see if it's charred. Not just black, but burned to the point to where it looks like it's about to fall apart.