Basic swap question - OS placement
Basic swap question - OS placement ok 
I'll be using the GMPP controller. For packaging reasons, will it work if I put the 2 O2 sensors BEHIND the cats?
This controller only has 2 sensors.
I'll be using the GMPP controller. For packaging reasons, will it work if I put the 2 O2 sensors BEHIND the cats?
This controller only has 2 sensors.
Teching In
Joined: Jul 2009
Posts: 9
Likes: 0
From: MN
no you would want to put them IN FRONT of the cats so the ecu can see what the engine is running at for fuel ratio's. If you put them after the cats it will run like ****! this is due to the fact that it is the cats job to "clean" the outgoing exhuast and the readings will be much much slower and way off
yeah if you watch the voltage from pre cat and post cat sensors, the precat sensors are up and down all the time, then the post cat sensors are flat lined (thats how the pcm knows the cats are working)
i dont know how it works really? but the sensors show high and low voltage for rich and lean, then they flatline high or low if the cat is working right.
its really interesting how the pcm is actually just bouncing back and forth trying to keep the air to fuel ratio right.
its really interesting how the pcm is actually just bouncing back and forth trying to keep the air to fuel ratio right.
