Tom r Posted March 27, 2013 Share Posted March 27, 2013 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 Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/ Share on other sites More sharing options...
h67st Posted March 27, 2013 Share Posted March 27, 2013 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. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/#findComment-174501 Share on other sites More sharing options...
felicello122 Posted March 27, 2013 Share Posted March 27, 2013 What h67st said, and get another guage to verify its working, also is your pyro reading higher? Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/#findComment-174502 Share on other sites More sharing options...
Mackpro Posted March 27, 2013 Share Posted March 27, 2013 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. Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/#findComment-174545 Share on other sites More sharing options...
Tom r Posted March 27, 2013 Author Share Posted March 27, 2013 Thanks guys im on hollidays for two weeks but as soon as i get back i will check these suggestions out and let you no Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/#findComment-174550 Share on other sites More sharing options...
Challenger Posted March 27, 2013 Share Posted March 27, 2013 Why's the dealer saying the boost pressure is correct if you're saying its low? Quote Link to comment https://www.bigmacktrucks.com/topic/30561-low-intake-manifold-pressure/#findComment-174566 Share on other sites More sharing options...
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