We have a 2001 Mack CH613 E-7 460 XT that I'm working on. Will not build consistent boost. Engine will suddenly build boost for 20 or 30 seconds and run great then it stops and goes back to no power. Truck doesn't have a wastegated turbo or a vgt turbo.
Checks I have made or performed. No lighting bolt, has only came on momentarily once in three weeks. Had some stored codes. Saved codes and then cleared. Went through the test procedures on the codes and came up with nothing. Fuel pressure at idle 68psi, at 1400+ rpm's 76psi. Base engine oil pressure at idle cold 60+ psi, hot at idle 22+ psi. Pressure checked air cooler and hoses, ok. Visually checked engine wiring harness and also wiggle tested some of the dash harness while the truck was driven by another driver. Also did a complete service on the engine.
Previous owner threw a bunch of parts on this truck (we just bought the truck last month)....new throttle pedal, numerous new fuel lines, new crossover valve, new turbo, etc, etc.
We took the truck to the local Mack dealer last week and they kept it all week. They swapped turbos just to check, swapped a known good ECU and ECM just to check. They replaced both timing sensors, fuel temp sensor, intake air temperature sensor, both coolant temp sensors and the boost pressure sensor. They checked, removed and cleaned the engine ground and frame ground.