Medium and Heavy Trucks
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Hi my name is***** will be glad to try to help. Check for air restrictions and leaks in the turbo boost/intake piping causing low boost as well. Check the turbo for free movement and that is spins freely without drag and no oil leaks are present from the compressor wheel. Let me know
Thanks for the update. Connect Cat ET software and do an injector test and also do a blowby test for low compression. Black smoke is overfueling or unburned fuel. Check the overhead. Possible injector problem or ECM hardware/software issue. Did this occur immediately, after other work done, or progress over time?
At idle you wont see much at all but you should expect to see over 25 PSI up to 35 PSI boost. Your fuel pressure should remain steady at 75-90 PSI and not drop under a load. Hook up some guages and monitor on a road test and see what you boost and fuel pressure is actually doing. Let me know
Boost is very low/ non existant.... Either you overlooked a leak in the intake piping or your turbo is no good.
2.2 Boost Pressure Sensor
The Boost Pressure Sensor is an absolute pressure sensor measuring intake manifold air pressure. Boost Pressure as displayed by service tools and communicated over the data link is the value obtained by subtracting the atmospheric pressure (as measured by the Atmospheric Pressure Sensor) from the absolute value measured by the Boost Pressure Sensor for all C-10, C-12, C-15 and C-16 engines.The Boost Pressure Sensor can measures pressures from 0 kPa (0 psi) up to 472 kPa (68psi). The sensor is supplied by the ECM with 5 Volts DC.
2.3 Atmospheric Pressure Sensor
The Atmospheric Pressure Sensor is an absolute pressure sensor measuring crankcase pressure. Both the Boost Pressure and Oil Pressure communicated to service tools and over the data link is calculated by subtracting the Atmospheric Pressure Sensor reading.The Atmospheric Pressure Sensor can measure pressures from 0 kPa (0 psi) to 116 kPa (16.8 psi). The sensor is supplied by the ECM with 5 Volts DC
You would backprobe to verify 5 volts in and then check voltage return from the sensor for 1-5 volts.
If you checked boost with a mechanical gauge and got close to 0 idle and full throttle under a load then you either have a bad turbo, large leak in the intake manifold or piping, or exhaust restriction.