Mazda 2007 CX-9, Особенности сервиса

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ON-BOARD DIAGNOSTIC [MZI-3.5]
01-02–12
Catalyst Efficiency Monitor
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The catalyst efficiency monitor uses an oxygen sensor before and after the catalyst to infer the HC efficiency
based on the oxygen storage capacity of the catalyst. During monitor operation, the PCM calculates the length
of the signal while the sensors are switching. Under normal fuel system feed back control conditions, high
efficiency catalysts have significant oxygen storage. This makes the switching frequency of the rear HO2S very
slow and reduces the amplitude, which provides for a shorter signal length. The front HO2S switches more
frequently with greater amplitude, which provides for a longer signal length. As the catalyst efficiency
deteriorates due to thermal and chemical deterioration, its ability to store oxygen declines. The rear HO2S
signal begins to switch more rapidly with increasing amplitude and signal length, approaching the switching
frequency, amplitude, and signal length of the front HO2S. The predominant failure mode for high-mileage
catalysts is chemical deterioration (phosphorus deposits on the front brick of the catalyst), not thermal
deterioration.
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Inputs from CHT, IAT, MAF, TP, CKP and vehicle speed sensors are required to enable the catalyst efficiency
monitor.
•
The DTCs associated with this test are DTC P0420 and P0430.
Because an exponentially weighted moving average algorithm is used to determine a concern, up to 6 driving
cycles may be required to illuminate the MIL during normal customer driving. If the PCM memory is reset or the
battery is disconnected, a concern illuminates the MIL in 2 drive cycles.
Evaporative Emission (EVAP) Leak Check Monitor
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The EVAP leak check monitor is an on-board strategy designed to detect a leak from a hole (opening) equal to
or greater than 0.508 mm (0.020 in) in the enhanced EVAP system. The correct functioning of the individual
components of the enhanced EVAP system, as well as its ability to direct fuel vapor to the engine, is also
examined. The EVAP leak check monitor relies on the individual components of the enhanced EVAP system to
either allow a natural vacuum to occur in the fuel tank or apply engine vacuum to the fuel tank and then seal the
entire enhanced EVAP system from the atmosphere. The fuel tank pressure is then monitored to determine the
total vacuum lost (bleed-up) for a calibrated period of time. Inputs from the CHT sensor, IAT sensor, MAF
sensor, vehicle speed, fuel level input and Fuel tank pressure sensor are required to enable the EVAP leak
check monitor.
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During the EVAP leak check monitor repair verification drive cycle, clearing the continuous DTCs and resetting
the emission monitors information in the PCM bypasses the minimum soak time required to complete the
monitor. The EVAP leak check monitor does not run if the key is turned off after clearing the continuous DTCs
and resetting the emission monitors information in the PCM. The EVAP leak check monitor does not run if a
MAF sensor concern is present. The EVAP leak check monitor does not initiate until the HO2S monitor is
complete.
Thermostat Monitor
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The thermostat monitor is designed to verify correct thermostat operation. This monitor is executed once per
drive cycle and has a monitor run duration of 300—800 s. If a concern is present, P0128 is set and the MIL is
illuminated.
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The monitor inspections the CHT sensor to warm up in a predictable manner when the engine is generating
sufficient heat. A timer is initialized while the engine is at moderate load and the vehicle speed is above a
calibrated limit. The target timer value is based on ambient air temperature at engine start-up. If the timer
exceeds the target time and CHT has not warmed up to the target temperature, a concern is indicated.
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The test runs if the start-up intake air temperature is at, or below the target temperature.
Inputs
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Includes: CHT, IAT, engine LOAD (from MAF sensor), vehicle speed input
On-board Diagnostic System (OBD) Readiness Test
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Allows verification of whether or not the OBD items (monitor items) set in the PCM have been successfully
completed.
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Fuel injection control, and CCM and non-CCM components, are constantly monitored since their status is
constantly diagnosed.
•
The status of intermittently monitored diagnostic items can be initiated by activating the initialization function for
diagnostic data.
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