JPH02228572A - Diagnostic apparatus for injector - Google Patents

Abstract

PURPOSE:To achieve an accurate trouble shooting constantly by comparing with a preset reference current value an injector load current value calculated based on an output of a current detection sensor to prevent misjudgment due to the cutting of a fuel. CONSTITUTION:This apparatus is provided with a current detection sensor 43, an injector diagnostic means 60, a fuel cutting judging means 58 and a diagnosis indicating means 59. When the cutting of a fuel is judged by the means 58, the means 60 is directed to stop diagnosing of an injector from the means 59 and when the removal of the cutting of the fuel is judged, the means 59 directs the means 60 to diagnose the injector. The means 60 calculates an injector load current value IL based on an output of a sensor 43 to compared with a preset reference current value IR thereby judging whether an injector operates normally or not.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injector diagnostic device that performs failure diagnosis of an injector controlled by an electronic control device mounted on a vehicle.

[Prior Art and Problems to be Solved by the Invention] In recent years, air-fuel ratio control using electronic υlI21 has become common in vehicles such as automobiles due to advances in semiconductor technology. In this air-fuel ratio control, an electronic control unit (EC(J)) is configured by a microcomputer, and this ECU controls intake air
The fuel injection amount is calculated according to the fuel injection amount, and a control signal is output to the injector to control the fuel injection a.

The control signal for the injector is usually a pulse signal synchronized with the engine rotation, and the control signal for the injector is a pulse signal that controls the fuel injection time of the injector, that is, the pulse width of the pulse signal.
By adjusting t/I 611, an amount of fuel commensurate with the amount of intake air is injected, and the air-fuel ratio is controlled.

Therefore, if the injector fails, the boat's fuel will not be injected in an amount commensurate with the intake air m, and the air-fuel ratio will become lean or rich, leading to worsening of exhaust emissions, lower engine output, and worse fuel efficiency.

For this reason, recently, the ECU is equipped with an electric circuit whose loads include actuators, etc., for control signals 4. For example, in Japanese Patent Laid-Open No. 63-27769, a current sensor consisting of a shunt is installed on the power supply bus of a plurality of electric circuits. The current sensor detects the current value of the power bus, and the detection circuit compares the detection signal of the current sensor with the control signal at that time to detect that the control item is in a normal operating state. A technique to do this has been disclosed8.

However, during deceleration or when the engine overspeeds, fuel is cut to the injector in order to save fuel, protect the catalytic converter, or protect the engine. This fuel cut outputs a pulse signal with an extremely narrow pulse width, and the fuel injection time of the injector is
That is, the fuel injection amount is set to O or a small amount, and the load current value of the injector becomes O or an extremely small value.

In such a state, the fuel is cut off and a narrow pulse signal of 6 widths is output, so the load current value of the injector is detected and diagnosed, and the injector current is determined to be abnormal. This will result in false judgments.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides an injector diagnostic device that can prevent erroneous determination when it is determined that fuel is low in injector failure diagnosis. It is intended to.

[Means for Solving the Problems] An injector diagnostic device according to the present invention compares an injector load current value calculated based on the output of a current detection sensor with a preset reference current value, and determines whether the injector is normal or not. an injector clinic means for determining whether the fuel is being cut, a fuel cut determining means for determining whether to cut the fuel based on signals from various detecting means for detecting the operating state; The injector diagnosis means instructs the injector diagnosis means to stop the diagnosis, and when it is determined that the fuel cut is canceled, the injector diagnosis means instructs the injector diagnosis.

[Function] With the above configuration, when the fuel cut determining means determines that the fuel is being cut, the diagnosis instructing means instructs the injector diagnostic means to stop the injector diagnosis, and when the fuel cut is determined to be cancelled, The diagnosis instruction means instructs the injector diagnosis means to diagnose the injector.

The injector diagnostic means calculates an injector load current value based on the output of the current detection sensor, and compares it with a preset reference current value to determine whether or not the injector is normal.

[Embodiments of the invention] The present invention will be described in detail below with reference to one drawing.

The drawings show one embodiment of the present invention, in which Fig. 1 is a functional block diagram related to the diagnostic device, Fig. 2 is a schematic diagram of the engine control system, Fig. 3 is a circuit block diagram, and Fig. 4 (a) is a current diagram. Detection sensor: An explanatory diagram showing the current detection sensor, Figure 4 (b) is a characteristic diagram of the current detection sensor, Figure 5 is a waveform diagram of the control signal and injector square charge current, and Figure 6 is a flowchart showing the injector operation confirmation procedure. ↑／ −t.

(Configuration of Engine Control System) In FIG. 2, reference numeral 1 is the engine body, and the figure shows a horizontally opposed four-cylinder engine. In addition, an intake port 1-2 formed in the cylinder head 2 of this engine body 1
An intake manifold 3 and an exhaust manifold 4 are respectively connected to the 8,1-no.
An ignition plug 5 exposed to the ignition plug 5 and an ignition coil 5a directly attached to the ignition plug 5 are attached to each cylinder.

In addition, there is a construction 71 on the upstream side of the intake manifold 3.
Throttle switch tI member 7 is communicated via 1 member 6,
The upstream side of the throttle valve 7 is communicated with an air cleaner 9 via a suction pipe 8.

Further, an intake air meter (a hot film air flow meter in the figure) 10 is interposed immediately downstream of the air cleaner 9 in the suction pipe 8, and a throttle sensor 10 provided in the throttle chamber 7 is installed. A throttle position sensor 11 is attached to the valve 7a, and an idle switch 11 detects the fully open position of the throttle valve 7a.
a are arranged consecutively.

Further, 1. An injector 12 is disposed for each cylinder immediately upstream of each intake boat 2a that communicates with the combustion chamber 1a of each cylinder of the intake manifold 3. Generally speaking, a water temperature sensor 13 faces a cooling water passage (not shown) formed in this intake manifold 3.

Further, an 02 sensor 15 faces the exhaust pipe 14 communicating with the exhaust manifold 4. In addition, the code|symbol 16 is a catalytic converter.

On the other hand, a crank rotor 17 is fixed to the crankshaft 1b of the engine body 1, and a cylinder discrimination cam rotor 18 is shielded from the camshaft 1C.

Further, a crank angle sensor 19 is provided on the outer periphery of the crank rotor 17, and furthermore, a crank angle sensor 19 is provided on the outer periphery of the crank rotor 17.
A cam angle sensor 20 is provided on the outer periphery of the cam 8 .

Further, reference numeral 21 is a vehicle speed sensor, and each of the above-mentioned sensors 10
．． 11, 13.15.19.20. And, together with the idle switch 11a, it is connected to the input end of an electronic control unit (ECU) 30. The injector 12 arranged in each cylinder and the igniter 22 consisting of a transistor are connected to the output end of the ECU 3O,
The igniter 22 is connected to the ignition coil 5a arranged in each cylinder.

Note that the symbol 23 is a key switch, and the symbol @24 is a battery.

(Circuit configuration of control device) The above ECU3O includes a CPU31, a ROM32, a RAM
33, backup RAM 34, timer 35, output interface 1 36, and input interface 37
are connected to each other via the pass line 38, and furthermore, the oscillation i1!531a is connected to the CPU 31 to supply a system clock serving as a reference for each timing. This system clock is counted by the free running counter of the timer 35, and the reference time of each timing can be known by reading the value of the free running counter.

Further, for example, four sets of transistors 40 are connected to the output interface 36 via a resistor 39, and each transistor 40 is connected to the injector 12 of each cylinder via a current limiting resistor 12a.

Furthermore, a self-diagnosis lamp 41 is connected to the output interface 36 to notify of abnormalities in the control system.

In addition, the power supply bus 42 extending from the battery 24 includes
An ml detection sensor 43 is provided, which connects the injector 12 from the power supply bus 42 through the current limiting resistor 12a.
The injector load current I[ supplied to the electric circuit leading to the transistor 40 through the injector is directly detected by the current detection sensor 43.

On the other hand, the input interface 37 is connected to the flow detection sensor 43, the battery 24, and various detection means 25 for detecting the operating state. Intake air amount sensor 10. Throttle position sensor 11. The water temperature sensor 13, sensor 15 and other analog output detection means 25, the current detection sensor 43 and the battery 24 are connected via an analog/digital (A/D) converter 44. , is converted into a digital signal and input. In addition, the crank angle sensor 19. Cam angle sensor 20. Vehicle speed center length 21. Various digital output detection means 25 such as the idle switch 11a are directly connected to the interface 37.

As shown in FIG. 4(a), the current detection sensor 43 has a transformer formed by winding an electric wire around an annular core 43a made of, for example, ferrite.
A is partially opened, a Hall element 43b is disposed at the opening thereof, and an amplifier 43c is connected to the Hall element 43b, and the whole is molded with, for example, resin.

Further, since the current detection sensor 43 can detect current without being directly connected to an electric circuit, it can detect current without adverse effects such as changes in the impedance of the electric circuit or reduction in noise margin.

] Also, when a control signal is output from the power supply bus 42 to the electric circuit constituted by the injector 12 and a current flows, a magnetic field is generated by this current, and the transformer consisting of the core 43a transforms the ball element 43b. @
The magnetic flux penetrates and a voltage is generated in the Hall element 43b.

The voltage generated in the Hall element 43b is applied to the amplifier 43.
It is amplified and output by C.

The characteristics of the current detection sensor 43 are shown in FIG. 4(b), in which the input signal current l and the output type pressure V have a substantially linear relationship; however, electrical variations inside the Hall element 43b, etc. Therefore, even when there is no input signal, a slight voltage output may exist as an offset voltage vO.

On the other hand, the ROM 32 stores fixed data such as a control program, and the RAM 33 stores the output 11/I of each sensor after data processing and the pig processed by the CPtJ 31. Stored. The backup RAM 34 also includes the injector 12, the igniter 22, each sensor 10, 11, 13.
15, 19゜20.21, Trouble data in the event of a failure in the idle switch 11a1 or the control system is stored, and is backed up in the battery 24 and stored even when the key switch 23 is OFF. Trouble data obtained can be stored for a long time.

The CPU 31 calculates various control data based on the various data stored in the RAM 33 in accordance with the control program stored in the ROM 32. Then, the CP LJ 31c, 1IiH: (temporarily stores the various υ control data in the RAM 33, and outputs control signals to electrical loads such as the injector 12 and igniter 22 via the output interface 37 at a predetermined timing. do.

For example, in air-fuel ratio control, the intake air m sensor 1
Calculate the intake air volume from the output signal of 0, and calculate this intake air m
The fuel injection m corresponding to the fuel injection time is calculated by adding various correction terms, and the time corresponding to the fuel injection time is set in the timer 35. Then, a pulse signal having a pulse width of the time set in the timer 35 is transmitted to the crank angle sensor 19,
Based on the output signal of the cam angle sensor 20, the injector 1 of the corresponding cylinder is activated at a predetermined timing in synchronization with the engine rotation.
Output to 2.

In addition, in the above CPtJ31, calculation of various control data,
Along with the output, self-diagnosis is performed, and if an abnormality is detected, the self-diagnosis lamp 41 is turned on (flashing) to notify the driver of the abnormality.

(Functional configuration) Next, regarding the functional configuration of the air-fuel ratio control of the above ECtJ30,
explain.

As shown in FIG. 1, the ECL 130 includes an engine rotation speed calculation means 50, an intake air amount extraction means 51, a basic fuel injection amount calculation means 52, and various increase correction coefficient setting means 53.
, air-fuel ratio feedback correction coefficient setting means 54, fuel injection amount setting means 55, cylinder discrimination means 56, output means 57,
Fuel cut determination means 58, diagnosis instruction means 59, injector diagnosis means 60. The injector diagnostic means 60 is composed of a storage means 61 (consisting of the ROM 32 and backup RAM 34) and a self-diagnosis means 62. Publicly, the injector diagnosis means 60 is composed of a negative current value calculation means 60a and an abnormality determination means 60b. I'm here.

In the engine rotation speed calculation means 50, the crank angle sensor
The engine speed N is determined based on the output signal from the intake air amount sensor 19, and the intake air calculation means 51 reads the output signal from the intake air amount sensor 10 to calculate the intake air ff1Q.

The main fuel injection ff1R outputs 1'u and 52r are the engine rotation speed N calculated by the carrot rotation speed calculation means 50 and the intake air f sieved by the intake air mother calculation means 51.
ltQ and ζ (main fuel injection fit-rp (Tp=KX
Q/N: is a constant).

Various increase correction coefficient setting means 53 determines various increases related to post-idling increase correction, throttle full-open increase correction, water temperature correction, and acceleration/deceleration correction based on the output signals of the idle switch 11a, throttle position height 11, and water temperature sensor 13. The air-fuel ratio feedback correction coefficient setting means 54 sets the air-fuel ratio feedback correction coefficient α based on the output waveform of the 02 sensor 15.

The fuel injection amount setting means 55 converts the basic fuel injection tAffiTp calculated by the standard fuel injection m calculation means 52 into various increase correction coefficients C0FF and air-fuel ratio feedback correction set by the various increase correction coefficient setting means 53. Corrected by the air-fuel ratio feedback correction coefficient α set by the coefficient setting means 54, the fuel injection is 1ffiT (Ti = Tp XC0E
FXα).

The cylinder determining means 56 counts the number of cam pulses input from the cam angle sensor 20 between the input of a crank pulse from the crank angle sensor 19 and the input of the next crank pulse, and counts the number of cam pulses input from the cam angle sensor 20. The next cylinder to inject is determined from the number of cam pulses and the number of cam pulses counted last time.

For example, if the number of cam pulses counted twice is 1" and the number of cam pulses counted this time is 3", the cylinder to be injected next is determined to be the #3 cylinder, and the number of cam pulses counted last time is n3n, and the number of cam pulses counted this time is n3n. Cam pulse number is 111
In the case of 111., the next cylinder to be injected is determined to be the #2 cylinder. Furthermore, the number of cam pulses counted last time is “1”.
If the number of cam pulses counted this time is 1121+,
Next, the cylinder to be injected is determined to be the #4 cylinder, and if the number of cam pulses counted last time is 2'' and the number of cam pulses counted this time is "1", the cylinder to be injected next is determined to be the #1 cylinder. .

Based on the cylinder discrimination result, a predetermined boat of the output means 57 is selected, and a pulse signal having a pulse width Pi corresponding to the fuel injection ff1Ti set by the fuel injection amount setting means 55 is outputted via the boat; The injector 12 of the corresponding cylinder is driven.

On the other hand, the fuel cut determination means 58 detects whether the idle switch 11a is ON or OFF, and
It is determined whether or not there is a deceleration operation C in which a has changed from OFF to ON, and vehicle speed data ■S from the vehicle speed sensor 31 is determined.
is equal to or higher than the set vehicle speed, the engine speed N output by the engine speed line means 50 and the fuel cut speed NF corresponding to the cold 7JI water WTW from the water temperature sensor 13.
It is determined whether or not the fuel cut conditions are satisfied.

When the fuel cut condition is satisfied, the pulse width Pi corresponding to the fuel injection ff1Ti is outputted to the fuel injection 1 setting means 55 to be smaller than the normal level, and the pulse width is outputted to the diagnosis instruction means 59.

In this case, if the fuel injection amount from the injector 12 is completely reduced to O during deceleration operation, when the deceleration state is accelerated again, the supply of the re-injected fuel into the intake boat 2a will be delayed, so the fuel will be slightly reduced. The pulse width Pi is made small so that the liquid is injected.

Incidentally, when the engine speed N is equal to or higher than the maximum allowable engine speed N1ax, it is assumed that the fuel cut condition is unconditionally satisfied, and troubles due to overspeeding of the engine are prevented. Further, the fuel cut rotation aNFc is stored in a part of the ROM 32 as a map with the minimum engine rotation speed required for fuel cut being the fuel cut rotation speed NI"C, and for example, the cooling water IT- as a parameter. put.

When the fuel cut determining means 58 determines that the fuel cut condition is satisfied and the fuel cut is to be performed on the injector 12, the diagnostic instructing means 59 prohibits the interrupt from the timer 35 to the CPU 31 and executes the injector diagnostic means 60.
If the fuel cut determination means 58 does not satisfy the fuel cut condition, the interrupt processing from the timer 35 to the CPU 31 is enabled, and the injector diagnosis means 60 starts the interrupt processing. enable.

The injector diagnostic means 60 executes an interrupt process for the CPU 31 started by the timer 35, and the load current value calculation means 6Qa sends a drive pulse signal P to the injector 12 from the output means 57.
The above current detection sensor 4 when inj is not output
The load current of the injector 12 is determined by reading the offset current value corresponding to the offset voltage O of No. 3 and the current value corresponding to the output value of the current detection sensor 43 when a predetermined time has elapsed after the start of outputting the drive pulse signal. The value is calculated and output to the abnormality determining means 60b.

That is, the current detection sensor 43 has a slight offset voltage vO at its output even when there is no input signal, and this offset voltage vO changes due to the influence of drift due to temperature changes, changes over time, etc., and also due to individual differences. Since the offset voltage vO varies, the output of the current detection sensor 43 is read when a predetermined time has elapsed after the start of outputting the control signal to the electric circuit, and the offset voltage vO is subtracted from this output to determine the circuit current value. Calculate.

For example, as shown in FIG. 5, when a predetermined time T1 has elapsed since the drive pulse signal IP4Pinj for the injector 12 was turned on, the current value [111 sample,
Offset voltage ■0 of the current detection sensor 43 at timing TO when the drive pulse signal Pinj is ON
By reducing the offset current value S LTO corresponding to
Actual load current value IL (I
t = ILH - ILTO) and repeat this for each pulse.

The abnormality determination means 60b determines that the load current mnn average means 0
Load current value I of the injector 12 calculated in a
and the reference current value tn stored in the storage means 61 to determine whether the load current value IL is larger than the reference current value IR, thereby determining whether the injector 12 is normal. .

The reference current value IR is, for example, the voltage B of the battery 24.
is stored in a part of the area of the storage means 61 (specifically, the ROM 32) as a table set in advance from the characteristics of the injector 12 using V as a parameter;
Drive pulse signal pinj for the injector 12
is output, the reference current value IR is determined from the table directly or by interpolation using the battery voltage BV at that time as a parameter.

In this case, only when the fuel cut is not performed by the diagnosis instructing means 59, the interrupt processing is started by the timer 35 and the injector 12 is diagnosed.
Misjudgment due to fuel cut does not occur.

For example, as shown by the broken line in FIG. 5, during fuel cut, the pulse width Pi of the drive pulse signal Pinj is extremely small, so the drive pulse signal Pinj is
When the sampling time T1 comes after the injector is turned off, it is already turned off, and when the load current value IL of the injector 12 is calculated from the output of the current detection sensor 43, it becomes ■L#O.

Therefore, in order to avoid erroneous determination due to fuel cut, activation of interrupt processing by the timer 35 is prohibited, and failure diagnosis of the injector 12 by the injector diagnosis means 60 is stopped. Then, when the fuel cut is canceled, the diagnosis by the injector diagnosis means 60 is resumed.

In the above self-nine place means 62, the above-mentioned 5! I! Regular judgment means 6
0F), when the injector 12 is determined to be abnormal, the trouble data is stored in the storage means 61, and an abnormality signal is output to turn on (blink) the self-diagnosis lamp 41 to notify that the injector 12 is abnormal. .

Incidentally, the trouble data stored in the storage means 61 is as follows:
When the vehicle enters a service station (dealer), the data can be read by connecting an external device, for example, a vehicle diagnostic device, to the ECU 3O, thereby easily detecting a malfunction of the injector 12, etc.

(Operation) Next, a procedure for confirming the operation of the injector 12 with the above configuration will be explained according to flowchart 17 in FIG.

First, step 5 of the program shown in FIG. 6(a)
In step 101, the fuel injection ffl T i is set, and then the process proceeds to step 5102, where it is determined whether the fuel cut condition is satisfied. If the fuel cut conditions are not satisfied, the process proceeds to step 5103, and if the fuel cut conditions are satisfied, the process proceeds to step 5104.

In step 5103, the interrupt from the timer 35 to the above-mentioned CP (J31) is permitted, enabling the injector diagnosing means 60 to start interrupt processing for fault diagnosis of the injector 12, and the process proceeds to step 3105.

On the other hand, if it is determined in step 3102 that the fuel cut condition is satisfied and the fuel cut conditions are satisfied, step 5104t"
The interrupt from the timer 35 to the CPLI 31 is prohibited, the failure diagnosis of the injector 12 by the injector diagnosis means 60 is stopped, and the process proceeds to step 5105.

In step 5ios, the drive pulse signal Pinj for the injector 12 of the corresponding cylinder is output at a predetermined timing, and the process returns to step 5IO1.

Next, when the interrupt for fault diagnosis of the injector 12 to the CPIJ31 is enabled as FF, the timer 3 is activated at timing TO of the rise of the drive pulse signal Pinj.
5 outputs an interrupt signal to the CPU 31, and at the same time the interrupt program shown in FIG. 6(b) is activated.
Step 5151r, Δ/D conversion n to the A/D converter 44
The first trigger signal is output, and the conversion of the output voltage signal of the current detection sensor 43 into a digital signal is started.

Next, when the process proceeds to step 5152, the current value I LTO corresponding to the offset voltage vO of the current detection sensor 43 at the sampling time TO in FIG.
4, it is converted into a digital signal and stored at a predetermined address in the RAM 33.

Next, in step 5153, the A/D converter 44
A/D conversion is started so that A/D conversion is started again when the driving pulse signal pinj rises, that is, from the first sampling time To to the next sampling time T1, while outputting the /D conversion end signal. The time is set in the timer 35 and the routine ends.

The above-mentioned sampling time T1 is, as shown by l1nj in FIG.
It is set appropriately according to the characteristics of the injector 12.

Next, when the sampling time T1 is reached, an interrupt signal is outputted from the timer 35 to the CPtJ31 again, and the interrupt program shown in FIG. sensor 4
A/D conversion of the output voltage signal No. 3 is started.

Next, the process proceeds to step 5202, where the A/DI! 1!
The output of the current detection sensor 43 converted into a digital signal by the device 44, that is, the current value [LTl] corresponding to the output voltage v1 at time 1 shown in FIG.
It is stored at a different address in 3.

Next, when the process advances to step 5203, the above step 520
The current value ILT1 corresponding to the output voltage v1 of the current detection sensor 43 stored in the RΔM33 at step 2 and the current value ILT1 of the current detection sensor 43 stored in the RAM 33 at step 5152 of the interrupt program at the previous sampling time TO. The load current value I of the injector 12 is determined from the current value I LTO corresponding to the offset voltage VO.
Take out L (IL=ILTIILTO), step 52
Proceed to 04.

In step 5204, the reference current value for the injector 12 is read from the ROM 32, and the reference current V
From iIR and the load current value calculated in step 3203 above, the diagnostic value IDIAC is calculated (to the old G=I
L-IR) and proceeds to step 5205.

In step 5205, the sign of the diagnostic value IDIAG calculated in step 5204 is determined, and the diagnostic value
If [)IAG is larger than O, 1, that is, if the circuit current value I[ is larger than the reference current value [], it is determined to be normal and the interrupt is terminated.

On the other hand, in step 5205, the diagnostic value I DIAG
When it is determined that the injector 12 is 0 or less, the process proceeds to step 3206, where it is determined that the injector 12 has failed, and the self-diagnosis means 62 backs up the trouble data of the injector 12 in which the failure has occurred to 1 [ΔM34, and also checks when the failure has occurred. The self-diagnosis lamp 41 is turned on (flashing) to warn of this.

Therefore, even if the fuel cut for the injector 12 is executed and the pulse width Pi of the drive pulse signal @Pinj becomes smaller than the sampling time T1 of the current detection sensor 43, the injector load current value It is set to IL#0 and determined to be abnormal. This prevents misjudgments.

[Effect of the Invention 1 As explained above, according to the present invention, when a fuel cut is performed on an injector, the diagnosis instruction means instructs the injector diagnosis means to stop the injector failure diagnosis, and the fuel cut is canceled. At this time, the diagnosis instruction means instructs the injector diagnosis means to perform a diagnosis, the load current of the injector is detected by a current detection sensor, and the load current value of the injector is compared with a preset reference current value to determine an abnormality. Therefore, erroneous judgments due to fuel cut are prevented, and accurate fault diagnosis can be performed at all times.
Reliability is improved and excellent effects are achieved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a functional block diagram related to the diagnostic device, FIG. 2 is a schematic diagram of the engine control system, FIG. 3 is a circuit block diagram, and FIG. ) is an explanatory diagram of the current detection sensor, Figure 4 <b> is a characteristic diagram of the current detection sensor, Figure 5 is a waveform diagram of the control signal and injector load current, and Figure 6 is the injector operation confirmation procedure. There is a flowchart C to show. 30...Electronic control I device, 43...Current detection sensor, 59...Diagnosis instruction means, 60...Injector diagnosis means, 1[...Load current value, IR...Reference current value.

Claims (1)

[Scope of Claims] Injector diagnostic means for determining whether or not the injector is normal by comparing an injector load current value calculated based on the output of a current detection sensor with a preset reference current value; Based on signals from various detection means,
a fuel cut determination means for determining fuel cut; and when the fuel cut determination means determines that fuel cut has occurred, instructs the injector diagnosis means to stop the diagnosis, and when it is determined that the fuel cut has been canceled, the injector diagnosis means is configured to perform a diagnosis of the injector. 1. A diagnostic device for an injector, comprising: diagnostic instruction means for giving instructions.