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BP Rationality Via DMTL Pressure Pump Reference Disclosure Number: IPCOM000250028D
Publication Date: 2017-May-18
Document File: 1 page(s) / 196K

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The Prior Art Database

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BP Rationality Via DMTL Pressure Pump Reference

Barometric Pressure (BP) data is used by engine controls to alter Air/Fuel ratio as air is less dense at

altitude. Vehicles may use a dedicated BP sensor or may infer the BP from MAP sensor during part

throttle drive. In a key off state, Manifold Air Pressure (MAP) sensor can also be a good surrogate for BP.

In either case the BP sensor or surrogate sensor needs to be rationalized as per CARB regulations. For

instance when the BP is low, most likely either the vehicle is at altitude or a weather front is moving

through the area. If BP sensor inference of BP fails, then it can have adverse effects on engine controls

and other diagnostics that utilize the BP data for fueling as well as diagnostic entry and thresholding

criteria. A method to rationalize the vehicle’s BP sensing apparatus becomes relevant and necessary.

Prior art methods may use other engine pressure sensors to rationalize BP. But if BP is being inferred

from those sensors (MAP for instance) or if engine does not have an Exhaust Gas Recirculation (EGR)

system (delta pressure sensor) then there may be limited options for rationality to other engine sensors.


The Diagnostic Module Tank Leakage (DMTL) is an Evap leak detection pump that has an internal change

over valve and a 0.02” orifice. DMTL measures pump “current draw” as the leak determination

response. When the DMTL pump is turned on with Change Over Valve (COV) off, it pressurizes a small

region of volum...