Determination Of Effective Injection Time - Mazda 2006 MX-5 Service Highlights

Determination of Effective Injection Time

• The PCM divides the engine operation conditions into control zones according to engine speed and engine
load and determines the effective injection time at each control zone to perform optimum air/fuel ratio control in
all engine driving ranges.
LARGE
INTAKE AIR AMOUNT
Start zone
Purpose
• Improved engine startability
Operation condition
• When engine speed is 500 rpm or less.
Determination of fuel injection time
• According to engine coolant temperature (ECT sensor) and engine speed (CKP sensor)
Feedback Zone
Purpose
• Improved fuel economy
• Improved exhaust gas purification
Control condition
• During engine operation other than high load volume increase zone and engine start zone.
Determination of fuel injection time
• During normal driving, the amounts of various correction types are added to the basic injection time to set to
the theoretical air/fuel ratio.
High load volume increase zone
Purpose
• Improved driveability
• TWC protection
Control condition
• Either the charging efficiency or the throttle valve opening angle is a fixed value or more.
Determination of fuel injection time
• Corrections are added to the basic injection amount and the high load coefficient is calculated according to the
engine speed, mass intake airflow amount and the throttle valve opening angle.
Excessive speed fuel cut zone
Purpose
• Engine protection
Control conditions
• When the engine speed is 7,000 rpm or more (WOT).
• When engine speed is 5,500 rpm or more and the engine coolant temperature is approx. -15 °C {5 °F} or less.
• When the following conditions continue for 2 min or more:
— Vehicle is stopped.
— Engine speed is 2,500 rpm or more.
— Engine coolant temperature is approx. 112 °C {234 °F}.
Note
• The PCM determines that the driver continues to unintentionally depress the accelerator pedal
Determination of fuel injection time
• Fuel injection time is set to 0 (fuel cut).
CONTROL SYSTEM
HIGH LOAD VOLUME
INCREASE ZONE
START
ZONE
FEEDBACK ZONE
ENGINE SPEED
EXCESSIVE SPEED
FUEL CUT ZONE
DECELERATION
FUEL CUT ZONE
HIGH
C3U0140S015
01–40–21
01–40