Ok, here's the deal....'00 Civic EX (D16Y8) Intake, cam gear advanced 2deg., race cat w/O2 sim., Apex'i N1 catback, MSD 6AL ignition, AEM fuel rail and pressure regulator, Apex'i VAFC. I ran into this problem shortly after installing the O2 sim. on the secondary O2 sensor. When the engine is under load, cruising between 2000 and 4000 RPM, my AFR guage registers lean (somtimes not even registering). The car stutters until either A.) i let off the accelerator or B.) the air/fuel mix restablizes. I've replaced my plugs, fuel filter, tuned the VAFC, and checked the ignition sys. but to no avail has the problem been fixed. The ECU is throwing a "primary O2 reading rich" code. The only things that I'm left with that I can think of is the injectors (possibly sticking), MAP sensor, and TPS sensor (since the latter two are used determine the A/F mix narrow throttle). Basically I'm looking for a little bit of input as to what all might be causing this and how to fix it. If anyone has run into this pblm. please speak up.

Thanx
Josh

 

SleeperCivicEX runs a VAFC on his boosted D16y8 and throws a 13 (map) and 45 (too rich/lean), but his car runs fine. The VAFC causes codes to be thrown even though the car runs fine. He even runs an O2 sim. as well.

You may want to PM him and get some info from him.

hih

 

could be your O2 sensor is just clogged. just pull it off and heat it with a propane torch till it turns cherry red. let it cool then put it back on. when you heat it with the torch it burns off all the carbon buildup.

 

oh yeah, i forgot to tell you, it's a brand new O2 sensor. I've already replaced it twice.

 

Is your cat clogged?

 

it's a straight through race cat.

 

could a map sensor be causing this pblm? if so where is the best place to go to get one decently priced and better quality than an OEM honda one? I've already had one go out on me before and that was before all the extensive mods.