Scantool

[Vettefan87]

Well earlier I hooked the vette up to a scantool, and everything looked okay except the O2 will go lean for a good twenty seconds, then flash rich for a few seconds, then back to lean. I always thought it went back and forth from rich to lean and what not. I am going to hook it up to my brothers car, and compare results. Anything I should look at specifically? What voltage is the O2 supposed to read?

 

[KOPBET]

... I always thought it went back and forth from rich to lean and what not.

I believe it should toggle between about 300mV (lean) to about 600 mV (rich) 5 or 6 times per second as the computer varies the injector pulse width in an attempt to obtain the ~14:1 ideal ratio.

I also thought that the 87s had an unheated O2 sensor, so make sure the engine is well warmed up while reading.

 

[Moonunit 451]

The sensor is unheated, BUT I don't recall what you did for location when you put on the headers. It should toggle from lean to rich quickly and continuously.

 

[Vettefan87]

At idle it doesn't. On my car it stays pretty much lean, and on my brothers car it stays pretty much on the rich side, but under driving conditions it does bo gack and forth but it is not right after each other. Other then that it all looks pretty good. No knock, and the spark advance is around 38 or so.