Quick update guys. I messed around with the truck all weekend, with very little luck. Did a compression check, all cylinders 220 psi +/- 5. Did a smoke check, could not find any vacuum leaks. Stonewalled. Totally scratching my head.... I had set up an appt to get the exhaust put back on yesterday. I almost cancelled it since the truck would hardly run, but since I had taken the day off, I went ahead and called a rollback and had it hauled to the exhaust shop. I had planned on putting on some new Magnaflows that I had laying around, but they wouldn't fit,
. I had wanted to switch the Magnaflows because I had read that they sound better with the LS motors, oh well....And with the new crossmember I built for the 6L80 tranny, my electric cutouts weren't working out so well either,
. So I just told the exhaust guy to reconnect the Flowmasters that were on there (50 series) and at least I could do some tuning without getting fumigated. OK, so we get everything hooked up and I start the truck up just to see how it sounds....and to my surprise, I like it! And to my even bigger suprise, I hook the HPTuners scanner up and all the issues I was having with misfires and crazy Fuel Trims were gone!!!! Other than running a little rich, the idle is good and it's not throwing any codes. So the Moral of the story is, NEVER do any tuning on a FI motor unless you have the exhaust on and don't believe everything you read on the internet,
. I'm eating some serious humble pie, I would never have thought that not having the exhaust on would have created the "symptoms" that I was seeing going on with my motor. Go figure. I did learn a lot through this experience, and will be a better "tuner" because of it. Now I have to undue some things I did when I was chasing a problem that wasn't there,
.