Help with LT4 engine swap in 2014 Silverado LTZ 2WD 6.2L
I replaced the stock 6.2L engine with a Chevy Performance LT4 crate engine. Kept the original ECU, wiring harness, 6L80E transmission, and TCM. Transmission rebuilt for 900hp and flashed TCM, and all other moving parts upgraded. My engine tuner didn't have any trouble with engine tune but we're pulling our hair out trying to get it to shift dependably. If I drive it like a little old lady there's no problem but from 50% to WOT it does strange things. May skip shift up or down, or may go thru 1st and 2nd, then search for a gear. We've tried adjusting TPS, torque settings, RPM shift points, etc. but not getting good results. We haven't found anybody else who has put this engine in a newer vehicle. Most people use manual transmissions or older automatics that don't require electronics so we're looking for somebody with experience in direct injection engines and 6L80 transmissions.
