8.3L viper engine rebuilt with new ported heads Greg Good/JTS Venom (Valves are oversized to 2.02 intake and 1.60 exhaust) and new Cam (629 lift intake / 628 exhaust lobe at 114°). When a base tune (created by a professional tuner) remotely, in preparation to drive to dyno for full tune. a problem was noted with the short-term fuel trims. “ It is adding a lot of fuel to Bank-1 and subtracting a lot from Bank-2”. New Bosch O2 upstream sensors already installed on Bank-1 and Bank-2 (same issue the previous O2 sensors ). Even though Up O2s have unique connectors….. to verify not swapped, one was disconnected and validated to be noted not responding on the correct bank in HP tuners software. A previous issue with two vacuum leaks were addressed to where now intake manifold pressure is 5.1-11.6 psi (3K rpms to idle). The engine was rebuilt with new spark plugs/wires, new OEM coil packs and all 10 injectors were cleaned. Fuel pressure verified 60 psi on Schrader valve on bank 2 rail (fuel comes in on bank 1 rail) both idle and under load (3K rpms). No leak on intake noted: sprayed stater fluid along runners of intake manifold plenum and no change in idle noticed. What would be the next troubleshooting step? I have HP Tuner and Bi-directional scanner available to test.
Image (Click to enlarge)
Mar 4, 2025 at 6:26 AM
