My car was just fine until after running the **** out of it at a local autocross event about 2 weeks ago (But I don't know if this is the cause). I have an Autometer A/F ratio meter I use in conjuction with a Field VTEC/Fuel controller. Just recently, I notice on the A/F meter that my fuel never reaches the rich zone under WOT. Even worse, when I'm cruising my fuel only reaches about 4 bars into stoich. and that's almost border line into lean (which I know may cause detonation = bad news). It never did this before, and I didn't mess with any of my fuel settings on the controller before or after I ran. If this helps, my settings on the fuel controller are:

-5 @ 2000rpm
-5 @ 3000rpm
-5 @ 4000rpm
-2 @ 5000rpm
-1 @ 6000rpm
0 @ 7000rpm
0 @ 8000rpm

So thinking that it could be the fuel controller I turn it off because when I do that the ECU kicks in it's original fuel maps and I can see the difference on the A/F meter (I use a P72 ECU (95 Integra GSR). Normally under WOT the stock fuel maps are shown to be really rich on the A/F meter, but when I push the gas this time, the fuel only hiked up 2 bars into stoich., not even entering the rich zone. Something has to be wrong!

My final conclusion is that the O2 sensor has clogged up so badly it can hardly read my air to fuel mixture anymore so it's sending this weak signal? What sucks also is that since my ECU is supposedly reading this lean signal the performance of my car has suffered, it doesn't pull as hard as it used to when more fuel was added, but I tell you my gas mileage is better

So, my question is... Has anyone been through the same thing? Is it a bad O2 sensor or something else? Any feedback and help is apprecated! By the way, suprisingly my car hasn't thrown any check engine lights so I can't diagnose the problem. Thanks!

 

???