Mazda 2006 MX-5 - Fuel Injection Control Operation [Lf]; Operation; Injection Time

CONTROL SYSTEM
01–40–20
FUEL INJECTION CONTROL OPERATION [LF]
E5U014000000N27
Operation
Injection timing
• There is synchronized fuel injection, which performs fuel injection by the setting of the crankshaft position, and
non-synchronized fuel injection which performs fuel injection when the condition for fuel injection is met
regardless of the crankshaft position.
Synchronized fuel injection
• The crankshaft rotation is synchronized by each intake and exhaust stroke of the cylinders, and fuel injection is
performed by the fuel injection timing and the injection amount corresponding to the input signals of the
following sensors.
— CKP sensor, MAF sensor, ECT sensor, IAT sensor
Non-synchronized fuel injection
• The crankshaft rotation is not synchronized and fuel injection is performed by the injection timing and injection
amount as triggered by the input signals of the following sensors.
— TP sensor, MAF sensor, ECT sensor, IAT sensor
Relation between synchronized and non-synchronized fuel injection
• If synchronized and non-synchronized fuel injection happen to occur together, fuel is injected by adding the fuel
injection timing of both.
Injection Time
• The PCM calculates the fuel injection amount according to the engine operation conditions as the fuel injection
time and energizes the fuel injectors.
Fuel injector energization time and operation conditions
• The fuel injectors cause an operation delay with
the start of energization from the PCM. The PCM
calculates the fuel injection time by adding the
non-injection time (ineffective injection time) with
the actual injection time (effective injection time),
and energizes the fuel injectors for this time.
• The fuel injection time is based on the following
formula:
Fuel injection time = effective injection time +
ineffective injection time
Ineffective injection time
— The fuel injectors cause a delay in operation
due to a delay in the build-up of operation
current from coil inductance with the start of
energization, and by the mass of the needle
valve and plunger, and spring resistance. This
delay is the ineffective injection time.
— The non-injection time is affected by the
change in battery voltage. Accordingly, the
PCM sets the non-injection time according to
the battery voltage
Effective injection time
— The fuel injector opening valve time which is
the actual fuel injection time is called the
effective injection amount.
ON
OFF
0
INJECTION
SIGNAL
FUEL INJECTOR
CURRENT
FUEL INJECTOR
FUEL INJECTION TIME
INEFFECTIVE
INJECTION TIME
EFFECTIVE
INJECTION TIME
FUEL INJECTOR OPENING
VALVE ELECTRICAL
CURRENT
FUEL INJECTOR VALVE
OPENING TIME
OPEN
CLOSED
C3U0140S014