Hi and new to the forum. Looking at my next project which involves a LS3/4l60 combination around 2002.. The vehicle, per the owner, has a harness supplied by the tuner which does not incorporate 02 sensors or MAF sensor. They put plugs into the 02 bungs on the header and nothing for the MAF. Vehicle appears to start and run good but can't imagine this doesn't affect mileage and performance. Regardless, If i get a harness that has those connections, can i plug them in and the engine will start and run and then have it tuned or is it more complex than that? No idea on the tune and don't really care since it would have to be done for correctly wired motor. Thoughts/suggestions? Thanks for any input, this is my first project.

 

If you can get O2's and MAF all plugged in properly, then go into the tune and reactivate it all. Then tune accordingly.

 

Lots of guys do not run a MAF. I’m in that camp myself. If you unplug the MAF on most any GM vehicle, the ECM jumps into Speed Density mode to rely on fuel trim calibrations. Not a big deal as long as the tune is correct, and steps are made to override the CEL throwing a MAF code. There’s a LOT to this, but that’s the short story.
Now, the O2 deal…you must be talking about the rear set of O2 sensors. The vehicle has a front set, and a rear set. It’s also very common to see guys remove the rear O2’s due to exhaust system mods. Again…as long as it’s tuned out in the ECM, it will not affect anything. If your in a State/County that mandates emmisions inspections then the rear O2 deal will affect you most likely, because again, I’d imagine that there has been exhaust system mods (maybe no cats) performed. The vehicle will not run without the front O2 sensors in place…at least it won’t run worth a flip anyway.
Just so you know what your buying, the LS3 didn’t show up until 2007…you mentioned this being a 2002? Be aware of what someone is trying to sell you. Do your homework.

 

Che70velle is correct; lots of guys run speed density tunes without a MAF. But you can also run without front O2's as well as rear. I did it myself for over a year with no issues. You tune the car to run off the fuel tables (like it does when cold in open loop) all the time. There is no feedback loop so you want your AFR tables to be correct.

There is a downside, however. One evening at the track when I was running that tune, as the outside air cooled, my buddy's car kept gaining time and mph. My times and mph stayed static.