For those of you with codes such as 4-3-5, or any other codes that pertain to poor performance of O2 sensors, try this. 

First of all, O2 sensors typically fail for one reason. REALLY *hitty gas, especially in Canada. The essentially dirty gas tends to leave deposits on the ceramic sensor within the exterior shield of the O2 sensor. These deposits often cause improper functioning of the sensor. Common contaminants from gasoline are MMT (the lead replacement which actually pollutes practically as bad as lead itself, just in other ways) and sulfur. Other forms of contamination include silicone from seals and gaskets, low quality fuel additives, engine oil, as well as many other sources. 

At this point, this is where the majority of us head to the dealership, only to find out the sensor is about $275 Canadian, plus about an hour or more for labour. 

However, if you are basically handy with a 22mm wrench, some brake cleaner, and a blow torch, this most common failure can be rather easily fixed. 

Lately, I had been pulling code 4-3-5 in the A2 socket. I have reset it a couple times now, and had been planning an O2 sensor replacement this Wednesday (Bosch 4 wire universal). However, an engineering friend had explained this process out to me and why it works, and I decided to give it a go. 

So this BEAUTIFUL, cool, fall morning, in Toronto, I removed the O2 sensor, torched it to burn off the contaminants, cleaned out the contaminant residue with brake cleaner, reinstalled, and I was simply amazed. It felt like new O2 sensors had been installed. Much more get up and go, easily 80% into the boost range on the gauge at full throttle (I have a number of mods to get the extra boost), spiking to about 85% on the 1-2 shift, much smoother idiling, not running nearly as rich, and in general, a better running engine. And I bet I'm going to get noticeable fuel savings. 

It took less than an hour, and with just how great the car was running, I just had to go for a drive to enjoy my baby, who recently got a full suspenion upgrade (springs, shocks/struts, anti-roll bars, bushings, etc). In fact, just thinking about how nice my baby is driving right now is making me want to go for another drive. 

I've got a tonne of studying to do for midterms in about a week, but I just can't resist :) Just one hour ;) 

BTW, for I believe derspi, I finally got around to playing with tthe adjustments on the Konis. Full soft makes the car feel SO luxurious, but really takes away from the performance. Full hard was ridiculously fun, but slightly jarring from the rear with the lightness in the back. I am running about 55%-60% stiff on the rear, and about 50% stiff on the front. With my recent allignment, and the shocks/struts at these settings, the car is remarkbly neutral. I can get the car into 4 wheel drifts without using the handbrake. And while in drift, the car SLIGHTLY understeers, making the car VERY predictable with a VERY high handling threshold.