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Low intake manifold pressure


Tom r

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He guys i have a 2006 mack vision 410hp it has lost power and the intake manifold pressure is only two thirds what it used to be ... Truck has new injectors and has been to mack and they say all boost and fuel pressures are correct.. But truck wont go like it used to :(

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I'm not up to snuff on newer Macks, but when I worked on trucks the biggest problem we saw was boost pressure leaks...split hoses, broken clamps, or cracked aftercooler. Look over all the pipes from your turbo to aftercooler and then to intake manifold.

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Boost pressure relief valve on top of intake maifold. a large brass valve/nipple that screws in to manifold and the turns to a rubber hose then into metal pipe that goes over the rear valve cover into the turbo exhaust pipe. They go bad alot. Has the boost pressure sensor been changed lately? There are 2 different part #s , if the wrong one is installed it will have low boost. Also turbo actuator sticking or to air to actuator, but should set a active code.

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