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www.mucarco.com
www.mucarco.com
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gradual adjustments to the fuel calibration schedule than short-term trim adjustments.
These long-term adjustments compensate for vehicle dierences and gradual changes
that occur over time.
3 Introduction to the Product
3.1 General introductions
MUCAR CS4 is the OBD product for DIY users. Equipped with Android operating system,
it features powerful functions and can be updated online. Moreover, full communication
protocols make it cover a wider range of vehicle models.
21 3 4
2.6 OBDII Denitions
Powertrain Control Module (PCM) -- OBDII terminology for the on-board computer that
controls engine and drive train.
Malfunction Indicator Light (MIL) -- Malfunction Indicator Light (Service Engine Soon,
Check Engine) is a term used for the light on the instrument panel. It is to alert the driver
and/or the repair technician that there is a problem with one or more of vehicle’s systems
and may cause emissions to exceed federal standards. If the MIL illuminates with a steady
light, it indicates that a problem has been detected and the vehicle should be serviced
as soon as possible. Under certain conditions, the dashboard light will blink or ash. This
indicates a severe problem and ashing is intended to discourage vehicle operation. The
vehicle onboard diagnostic system cannot turn the MIL o until the necessary repairs are
completed or the condition no longer exists.
DTC -- Diagnostic Trouble Codes (DTC) that identies which section of the emission
control system has malfunctioned.
Enabling Criteria -- Also termed Enabling Conditions. They are the vehiclespecic events
or conditions that must occur within the engine before the various monitors will set, or
run. Some monitors require the vehicle to follow a prescribed “drive cycle” routine as part
of the enabling criteria. Drive cycles vary among vehicles and for each monitor in any
particular vehicle. Please refer to the vehicle's factory service manual for specic enabling
procedures.
OBDII Drive Cycle -- A specic mode of vehicle operation that provides conditions
required to set all the readiness monitors applicable to the vehicle to the “ready” condition.
The purpose of completing an OBDII drive cycle is to force the vehicle to run its onboard
diagnostics. Some form of a drive cycle needs to be performed after DTCs have been
erased from the PCM’s memory or after the battery has been disconnected. Running
through a vehicle’s complete drive cycle will “set” the readiness monitors so that future
faults can be detected. Drive cycles vary depending on the vehicle and the monitor that
needs to be reset. For vehicle specic drive cycle, consult the service manual.
Freeze Frame Data -- When an emissions related fault occurs, the OBDII system not only
sets a code but also records a snapshot of the vehicle operating parameters to help in
identifying the problem. This set of values is referred to as Freeze Frame Data and may
include important engine parameters such as engine RPM, vehicle speed, air ow, engine
load, fuel pressure, fuel trim value, engine coolant temperature, ignition timing advance, or
closed loop status.
Fuel Trim (FT) -- Feedback adjustments to the base fuel schedule. Short-term fuel trim
refers to dynamic or instantaneous adjustments. Long-term fuel trim refers to much more
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