I refreshed a 6.2 / GM4 turbo, complete rebuild, pistons, bearings, heads, injectors, IP (mechanical), glow plugs. 500 miles around town break-in no problems, took a short road trip (100 miles) lost power, limped last 10 miles, couldn't get over 50 mph, lots of blue smoke. Trailered home, pulled turbo, exhaust manifold, glow plugs (#6 burned) compression tested @ 400lbs each cylinder. Leak down test on #6 good. Pulled injectors and sent them back for testing figuring #6 was leaking. Heard back on the injectors and they were all good. Chatting with injector rebuilder and he said sounds like the IP is over fueling and maybe advance piston is worn and I tell him he rebuilt the pump 600 miles ago then he thought the timing was off. I have a Kent Moore Tach and Time and set the timing @ 4 degrees advance, jumping the cold advance brings the timing to 6 degrees advance. Timing was done at 1300 RPM. I checked the timing tonight and it might be closer to 3.5 degrees now, along with a garage full of blue smoke. Still think IP is over fueling but I can't say for sure.
Opinions?
Thanks!