MP7 engine with comcustion air valve error during regen

This topic contains 1 replies and was last updated by kenneth-smart 8 years 5 months ago
June 22nd, 2013 9:30am
I am trying to regen a Mack MP7 engine but get a combustion air valve error during the regen process. Any help on diagnosing or starting the diagnosis process would be greatly appreciated. The master air valve does operate with no problem.
June 27th, 2013 7:08am
I do not have any experience on Mak engines so take my advise knowing that fact. The fault code that is logging is indicating that flow is the issue. The combustion air valve may be functioning properly but the sensor which measures the flow may not be. Also, air mass flow is usually measured thru a venturi, and if the Mak engine has one of these, you will want to check the venturi ports for plugging. Also check whatever components link the mass flow sensor to the venturi for leak sources that will give false readings. Finally, if the turbocharger(s) is not functioning properly there can be a low flow condition. Check your turbo wheels for damage and check for any sources for boost leaks. If the turbo is of variable geometry design, you will also need to verify that the actuator and mechanical linkage are not binding. This can usually be accomplished by running a test with an electronic service tool. If you don't have that tooling you could disconnect the linkage from the actuator and check it that way. Then try to run a regen with it connected and watch to see if the actuator moves. If it doesn't, that could be the problem. Start with the basics that I mentioned first.

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