I just bought some autolite 3923 spark plugs and I wanted to know what I should torque them down too??? Thanks. Also got a new bosch o2 sensor so hopefull the fuel milage will go up!!

 

+1[sm=vader.gif] how many o2 sensors you have i think i have like 3 its a cali emissions truck [sm=shootshoot.gif]*** me running

 

25 ft/lbs is std torque.
Basically that's snug plus about 1/3 of a turn. Same for O2 sensor.
Do your self a favor and blow out around the spark plugs before you remove them. Those heat tube are a great place for rust and crud to collect and it can fall into the cylinder when you remove the plug.A bit of anti seize on the plug threads is a good idea too.

 

two but the second just makes sure the cat is working

 

Yea just replace the front one, that actually controls fuel mixture

 

The back one does affect fuel trim as well, not as much as the front though.
True therear monitors cat efficiency, but the cat needs some excess fuel to burn to keep thetemp high enough to burn off all the pollutants. (NoX, CO, HC, etc)
So a weak Cat or a rear sensor that not sensitive can cause your truck to run too rich.
The system is more concerned about emissions then economy and is biased toward that.

That why a goodO2 sim will simulate a very efficient converter

 

Thanks and what is a good sim then?

 

This is the one I would buy based on the fastmans rep.

http://www.thefastman.com/02Simms.asp

 

I got my sim from him. Good quality product, easy instalation. I didnt secure mine properly and i found out about 3000 miles later it was swinging and slamming up against the framerail....still works.