hehe my title sounds kinda dirty but anyways.

I need some help understanding my s4 engine. I did a search for this stuff but couldn't find quite the info I wanted.

First do the primary injectors completly shut off when the secondaries tunr on or do they work together above 3000 rpms.

Second I want to tap into my O2 sensor with a DMM so I can see if the variable resistor is in the right spot. What voltage is stoich? Or what voltage should I want at WOT?

 

The primaries do not shut off. Their duty cycle just drops to 40% when the secondaries kick in. The 02 sensor is worthless at WOT. I forget what the switchover voltage is but someone will post it. A narrow band O2 sensor is really only useful to tell you stoich. It isn't accurate anywhere else.

 

Well how easy is it to put the resistor into a dangerous lean spot? It had been messed with by the previous owner whose craftsmanship or knowledge I dont respect at all.

 

Anyone have the voltage I'm looking for. Also I think narrow band O2's dont get enough credit. Yeah they suck for ground up engine tuning but if your car has been altered very slightly than they should be good enough to get you back to stoich safely.

Also I was wondering something about catalytic converters. I want to get rid of the factory one and put a high flow one in when I build a header. I heard though that the high EGT of rotaries have causes a short life span. Is this true. Anyone running fine on a cat from summit racing? Or does anyone know where to get a cat that will handle high temps. I have seen the units one company sells for rx7's as a direct replacment but it is pretty expensive.

 

catco.com

 

Still looking for that voltage..........

 

0.5 to 1.0 volts