JP2001329894A - Fuel system abnormality diagnostic device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid such a wrong diagnosis that the temporal disorder of the air-fuel ratio caused by the purge of vaporized fuel gas is regarded as an abnormality in a fuel system. SOLUTION: When the conditions to execute diagnosis are satisfied after the count value of an warming counter exceeds a specified value (after the finish of engine warming), primary diagnosis is carried out for preliminary diagnosing the presence and absence of abnormality in the fuel system (Steps 101 to 108). In the primary diagnosis, the time period for which a learning correction factor remains out of a specified range is integrated by a primary diagnosis abnormality counter, and if the integrated value exceeds, it is diagnosed that there is an abnormality in the primary diagnosis, and then secondary diagnosis is carried out. In the secondary diagnosis, the time period for which the total value of a learning correction value, that is, the abnormality diagnosis parameter in the secondary diagnosis, and a feedback correction factor remains out of a specified range is integrated by a secondary diagnosis abnormality counter, and if the integrated value exceeds a specified value, it is diagnosed that there is abnormality also in the secondary diagnosis, and such diagnosis that there is abnormality is decided finally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel system abnormality diagnostic device for an internal combustion engine that diagnoses whether there is an abnormality in a fuel system.

[0002]

2. Description of the Related Art In recent years, electronically controlled automobiles are equipped with a fuel system abnormality diagnosis system for self-diagnosing whether there is an abnormality in a fuel system for supplying fuel to an engine. The current fuel system abnormality diagnosis system learns by learning an air-fuel ratio feedback correction coefficient FAF for feedback-controlling the air-fuel ratio of exhaust gas to around a target air-fuel ratio and a deviation amount of an actual air-fuel ratio from the target air-fuel ratio. In many cases, the correction coefficient is summed, and the sum (abnormality diagnosis parameter) is compared with an abnormality determination value to diagnose the presence or absence of an abnormality in the fuel system.
Further, as disclosed in Japanese Patent Application Laid-Open No. H11-82117, in addition to the air-fuel ratio feedback correction coefficient FAF and the learning correction coefficient, the deviation of the actual air-fuel ratio from the target air-fuel ratio is also taken into consideration, and the sum of these three values ( It has been proposed to compare the abnormality diagnosis parameter) with an abnormality determination value to diagnose the presence or absence of an abnormality in the fuel system.

[0003]

In today's automobiles, in order to prevent the fuel vapor evaporated in the fuel tank from leaking into the atmosphere, the fuel vapor evaporated in the fuel tank is adsorbed by a canister. A fuel evaporative gas purging system is provided which opens a purge control valve on the outlet side of the canister under a predetermined condition during operation and discharges (purges) a fuel evaporative gas component from the canister into an intake pipe. However, when a high concentration of fuel evaporative gas is purged into the intake pipe at a light load where the intake air amount is small, the actual air-fuel ratio may be temporarily shifted to the rich side temporarily, thereby causing the actual air-fuel ratio to deviate from the target air-fuel ratio. As the deviation amount of the actual air-fuel ratio increases, the air-fuel ratio feedback correction coefficient FAF may change significantly due to the influence. For this reason, in the above-mentioned conventional fuel system abnormality diagnosis system, if a high concentration fuel evaporative gas is purged at a light load, the abnormality diagnosis parameter may temporarily be out of a normal range. In spite of this, there is a possibility that an erroneous diagnosis is made as an abnormality.

The present invention has been made in view of such circumstances, and accordingly, it is an object of the present invention to erroneously diagnose a temporary disturbance in the air-fuel ratio due to purging of fuel evaporative gas or the like as an abnormality in the fuel system. It is an object of the present invention to provide a fuel system abnormality diagnosis device for an internal combustion engine that can avoid the problem and perform highly reliable fuel system abnormality diagnosis.

[0005]

Generally, the learning correction amount obtained by learning the deviation amount of the actual air-fuel ratio from the target air-fuel ratio is learned with an appropriate delay in order to prevent erroneous learning. The change in the learning correction amount is compared with the change in the feedback correction amount of the air-fuel ratio to make it gentler, or
When the fuel evaporative gas is purged, learning of the learning correction amount is prohibited, and the learning correction amount is not changed by learning, so that the learning correction amount can be kept within the normal range.

Focusing on this point, the fuel system abnormality diagnosis apparatus for an internal combustion engine according to claim 1 of the present invention performs a primary diagnosis of the presence or absence of a fuel system abnormality based on a learning correction amount, and determines that the diagnosis result is abnormal. In the event that the abnormality is detected, the secondary diagnosis of the presence or absence of an abnormality in the fuel system is performed based on the learning correction amount and the feedback correction amount, and when the abnormality is diagnosed again, the diagnosis of the abnormality is finally determined. is there. In this way, even when high-concentration fuel evaporative gas is purged into the intake pipe at a light load, the abnormality diagnosis parameter (learning correction amount) remains within the normal range in the primary diagnosis performed based on the learning correction amount. Therefore, it is not diagnosed that there is an abnormality in the primary diagnosis. This avoids erroneous diagnosis of a temporary disturbance in the air-fuel ratio due to the purging of fuel evaporative gas or the like as an abnormality in the fuel system.

On the other hand, when an abnormality occurs in the fuel system, the state in which the air-fuel ratio is abnormal continues, so that when performing the primary diagnosis based on the learning correction amount, the abnormality diagnosis parameter (learning correction amount) is out of the normal range. The primary diagnosis diagnoses that there is an abnormality. In this case, the presence or absence of an abnormality in the fuel system is secondarily diagnosed based on the learning correction amount and the feedback correction amount. If the abnormality is diagnosed again, the abnormality diagnosis result is finally determined. As described above, by performing the abnormality diagnosis twice, a highly reliable fuel system abnormality diagnosis can be performed.

In this case, when the secondary diagnosis of the abnormality of the fuel system is performed based on the learning correction amount and the feedback correction amount, the learning correction amount and the feedback correction amount are summed up. The total value may be used as an abnormality diagnosis parameter to make a secondary diagnosis of the presence or absence of an abnormality in the fuel system. This simplifies the arithmetic processing at the time of secondary diagnosis.

Further, at the time of the primary diagnosis and the secondary diagnosis, the time during which each abnormality diagnosis parameter is outside the predetermined range is integrated, and when the integrated time reaches the predetermined time, it is determined that there is an abnormality. The diagnosis may be made. In this way, it is not necessary to erroneously diagnose a temporary sudden change in the abnormality diagnosis parameter due to noise or the like as an abnormality.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine. An intake air temperature sensor 14 for detecting an intake air temperature THA is provided downstream of the air cleaner 13.
An air flow meter 10 for detecting an intake air amount Ga is provided. Downstream of the air flow meter 10, a throttle valve 15 and a throttle opening sensor 16 for detecting the throttle opening TH are provided.

Further, an intake pipe pressure sensor 17 for detecting the intake pipe pressure PM is provided downstream of the throttle valve 15, and a surge tank 18 is provided downstream of the intake pipe pressure sensor 17. An intake manifold 19 for introducing air into each cylinder of the engine 11 is connected to the surge tank 18, and an intake manifold 19 for each cylinder is provided.
A fuel injection valve 20 for injecting fuel is attached near each intake port. This fuel injection valve 20 is
A fuel system is formed together with the fuel tank 40, a fuel pump (not shown), and the like, and the fuel pumped up from the fuel tank 40 by the fuel pump is distributed to the fuel injection valve 20 of each cylinder through a fuel pipe (not shown). .

The fuel evaporative gas evaporating from the fuel tank 40 is adsorbed by an adsorbent (not shown) such as activated carbon in the canister 42 through the communication pipe 41. A purge pipe 44 is provided between the canister 42 and the intake pipe 12 for purging (releasing) the fuel evaporative gas adsorbed in the canister 42 to the intake pipe 12. Purge control valve 4 for adjusting the purge flow rate
5 are provided. A fuel evaporative gas purge system 46 is composed of the canister 42, the purge control valve 45, the purge pipe 44, and the like.

The engine 11 is provided with an ignition plug 21 for each cylinder. Each ignition plug 21 receives a high-voltage current generated by an ignition circuit 22 from a distributor 23.
Is supplied via The distributor 23 is provided with a crank angle sensor 24 that outputs, for example, 24 pulse signals every 720 ° C. (two rotations of the crankshaft). The output pulse interval of the crank angle sensor 24 detects the engine speed Ne. It is supposed to. The engine 11 is provided with a water temperature sensor 38 for detecting an engine cooling water temperature THW.

On the other hand, an exhaust port (not shown) of the engine 11 is connected to an exhaust pipe 26 via an exhaust manifold 25. In the exhaust pipe 26, harmful components (CO, HC, NOx, etc.) in the exhaust gas are connected. ) Is provided. On the upstream side of the catalyst 27,
A wide-band air-fuel ratio sensor (linear A / F sensor) 28 that outputs a linear air-fuel ratio signal λ according to the air-fuel ratio of the exhaust gas is provided. An oxygen sensor 29 whose output voltage R / L is inverted depending on whether the air-fuel ratio of the exhaust gas is rich or lean with respect to the stoichiometric air-fuel ratio is provided downstream of the catalyst 27. It should be noted that the broadband air-fuel ratio sensor 28 upstream of the catalyst 27
, An oxygen sensor may be used.
A wide band air-fuel ratio sensor may be used in place of the oxygen sensor 29 on the downstream side of.

The outputs of the various sensors described above are read into the engine control circuit 30 via the input port 31.
The engine control circuit 30 is mainly composed of a microcomputer and includes a CPU 32, a ROM 33 (storage medium), a RAM 34, a backup RAM 35 backed up by a battery (not shown), and the like. To calculate the required fuel injection amount TAU, ignition timing Ig, and the like, and output a signal corresponding to the calculation result from the output port 36 to the fuel injection valve 20 and the ignition circuit 22 to control the operation of the engine 11.

The engine control circuit 30 executes an air-fuel ratio control program (not shown) to set a feedback correction coefficient (feedback correction amount) for feedback-controlling the air-fuel ratio of exhaust gas to near the target air-fuel ratio. At the same time, the deviation of the actual air-fuel ratio from the target air-fuel ratio is learned, and the learning correction coefficient (learning correction amount) is backed up.
M35 is updated and stored, and the required fuel injection amount TAU is calculated using the air-fuel ratio feedback correction coefficient and the learning correction coefficient to control the fuel injection amount. These functions correspond to an air-fuel ratio feedback unit, a learning unit, and a fuel injection control unit described in the claims.

Further, the engine control circuit 30 has a ROM 3
By executing the abnormality detection program of FIG. 2 stored in FIG. 3, the primary diagnosis of the presence or absence of an abnormality in the fuel system is performed based on the learning correction coefficient. Based on the total value of the fuel ratio feedback correction coefficient and the secondary value, a secondary diagnosis is made on the presence or absence of an abnormality in the fuel system, and when the abnormality is diagnosed again, the diagnosis of the abnormality is finally determined. A lighting signal is output to 37 to turn on the warning lamp 37 to warn the driver. Further, the engine control circuit 30 executes the normality detection program of FIG. 3 stored in the ROM 33, thereby diagnosing whether the fuel system is normal based on the learning correction coefficient and the air-fuel ratio feedback correction coefficient. . Hereinafter, the flow of processing of each program executed by the engine control circuit 30 will be described.

The abnormality detection program shown in FIG. 2 is started at predetermined time intervals and plays a role as abnormality diagnosis means in the claims. When this program is started, first, in step 101, it is determined whether or not an engine warm-up condition is satisfied based on the following condition. Cooling water temperature is higher than a predetermined temperature Intake air temperature is higher than a predetermined temperature Elapsed time after engine start is longer than a predetermined time Engine rotation speed is within a predetermined range Intake air amount is higher than a predetermined value The idle switch that detects the fully closed state of the throttle must be off.

When all of these conditions are satisfied, the engine warm-up condition is satisfied, and the routine proceeds to step 102, where the warm-up counter is counted up and the time during which the engine warm-up condition is satisfied is integrated. And the next step 1
At 03, it is determined whether or not the engine warm-up has ended based on whether or not the count value of the warm-up counter (the integrated value of the time during which the engine warm-up condition is satisfied) exceeds a predetermined value. if,
If the count value of the warm-up counter is equal to or less than the predetermined value, it is determined that the engine warm-up is not completed, and
Then, the primary diagnosis abnormality counter and the secondary diagnosis abnormality counter are both reset to 0, and the program is terminated.

Thereafter, when the count value of the warm-up counter exceeds a predetermined value, it is determined that the engine warm-up has been completed, and the process proceeds from step 103 to step 105 to determine whether or not the abnormality diagnosis execution condition is satisfied. Is determined based on the following conditions. Transient correction (for example, injection amount correction at low temperature) is not being performed. Leak check of fuel evaporative gas purge system 46 is not being performed. Purge control valve 45 is not being checked for operation.

The condition is that the deviation of the air-fuel ratio becomes large during the transient correction period. The condition is that the purge control valve 45 is opened and a large amount of fuel evaporates from the canister 42. This takes into account the fact that the gas component flows into the intake pipe 12 and the deviation of the air-fuel ratio increases. If any one of these three conditions is not satisfied, the abnormality diagnosis execution condition is not satisfied, and the program is terminated without performing the subsequent processing.

On the other hand, if all three conditions are satisfied at the same time, the abnormality diagnosis execution condition is satisfied, and the next step 1 is executed.
At 06 to 108, the primary diagnosis is made as to whether or not the fuel system is abnormal as follows. First, at step 106, the learning correction coefficient, which is an abnormality diagnosis parameter of the primary diagnosis, is out of the predetermined range (learning correction coefficient <rich side determination value H1R or learning correction coefficient>
It is determined whether or not it is the lean side determination value H1L). If it is determined that the value is out of the predetermined range, the process proceeds to step 107, where the primary diagnosis abnormality counter is counted up, and the learning correction coefficient is out of the predetermined range. Integrate the time.

In the next step 108, it is determined whether or not the count value of the primary diagnosis abnormality counter (the integrated value of the time during which the learning correction coefficient is outside the predetermined range) exceeds a predetermined value.
If the value is equal to or less than the predetermined value, no abnormality in the fuel system is detected, and the program ends without performing the subsequent secondary diagnosis processing.

Thereafter, when the count value of the primary diagnosis abnormality counter exceeds a predetermined value, it is diagnosed that there is an abnormality in the primary diagnosis, and the secondary diagnosis after step 109 is executed. In the secondary diagnosis, first, in step 109, it is determined whether or not the total value of the learning correction coefficient and the feedback correction coefficient, which are abnormality diagnosis parameters of the secondary diagnosis, is outside a predetermined range, that is, the learning correction coefficient + the feedback correction coefficient. <Rich side determination value H2R or learning correction coefficient + feedback correction coefficient>
It is determined whether or not the value is the lean determination value H2L. If it is determined that the value is outside the predetermined range, the process proceeds to step 117, where the secondary diagnosis abnormality counter is counted up, and the total value of the learning correction coefficient and the feedback correction coefficient is calculated. Is accumulated outside the predetermined range.

In the next step 110, it is determined whether or not the count value of the secondary diagnosis abnormality counter (the integrated value of the time during which the total value of the learning correction coefficient and the feedback correction coefficient is outside a predetermined range) exceeds a predetermined value. Is determined, and if the value is equal to or less than the predetermined value, the program is terminated without diagnosing the abnormality of the fuel system.

Thereafter, when the count value of the secondary diagnosis abnormality counter exceeds a predetermined value, the secondary diagnosis is also diagnosed as having an abnormality, and the routine proceeds to step 112, where the abnormality diagnosis is finally determined. In this case, a lighting signal is output from the output port 36 to the warning lamp 37 to turn on the warning lamp 37 to warn the driver and to store the abnormality information in the backup RAM.
35 is stored.

Next, the processing contents of the normality detection program shown in FIG. 3 will be described. This program is started at predetermined time intervals. First, in steps 201 to 203, step 1 in FIG.
If the count value of the warm-up counter that accumulates the time during which the engine warm-up condition is satisfied is equal to or less than a predetermined value, it is determined that the engine warm-up has not been completed, and Proceeding to 204, the normal counter is reset to 0, and this program ends.

Thereafter, when the count value of the warm-up counter exceeds a predetermined value, it is determined that the engine warm-up has been completed, and the routine proceeds from step 203 to step 205, where it is determined whether or not the normality determination condition is satisfied. The determination is made based on the following conditions. The learning correction coefficient is within a predetermined range (rich side determination value H1R ≦ learning correction coefficient ≦ lean side determination value H1L) The total value of the learning correction coefficient and the feedback correction coefficient is within a predetermined range (rich side determination value H2R ≦ learning correction coefficient + feedback correction coefficient ≦ lean-side determination value H2
L)

If either one of these two conditions is not satisfied, the routine proceeds to step 204, where the normal counter is reset to 0 and the program is terminated. Thereafter, when the two conditions are satisfied at the same time, the process proceeds to step 206, where the normal counter is counted up,
The time during which the normality determination condition is satisfied is integrated. And
In the next step 207, it is determined whether or not the count value of the normal counter (the integrated value of the time during which the normality determination condition is satisfied) has exceeded a predetermined value. Then, the program ends.

Thereafter, when the count value of the normal counter exceeds a predetermined value, the routine proceeds to step 208, where the normal judgment is finally determined, and both the primary diagnosis abnormality counter and the secondary diagnosis abnormality counter are reset to zero. It should be noted that the result of the diagnosis of the abnormality / normality of the fuel system is also used for the abnormality diagnosis of another system.

The operation and effect of the above-described fuel system abnormality diagnosis of this embodiment will be described with reference to the time charts of FIGS. FIG. 4 is a time chart showing the behavior of each operation parameter when the purge control of the fuel evaporative gas purge system 46 is performed when shifting from the steady state to the deceleration state. FIG. FIG. 5 is a time chart showing the behavior of the conventional fuel system abnormality diagnosis performed under the conditions shown in FIG.
(B) is a time chart showing the behavior of the fuel system abnormality diagnosis of the present embodiment performed under the operating conditions of FIG. As shown in FIG. 4, when a high concentration fuel evaporative gas is purged from the fuel evaporative gas purge system 46 into the intake pipe 12 at a light load with a small intake air amount, the actual air-fuel ratio temporarily increases to the rich side. Due to the deviation, the feedback correction coefficient changes greatly as shown in FIG.

In the conventional abnormality diagnosis method shown in FIG. 5A, the abnormality diagnosis is performed by comparing the total value of the feedback correction coefficient and the learning correction coefficient with the judgment value. When the coefficient greatly changes, the total value of the feedback correction coefficient and the learning correction coefficient, which are the abnormality diagnosis parameters, falls below the rich-side determination value, and the abnormality counter starts counting up. Since this state continues for a while, the count value of the abnormality counter eventually reaches a predetermined value, and the result is that the fuel system is erroneously diagnosed as abnormal even though the fuel system is normal.

On the other hand, in the present embodiment, the change in the learning correction amount obtained by learning the deviation amount of the actual air-fuel ratio from the target air-fuel ratio is more gradual than the change in the feedback correction coefficient. Attention is focused on, based on the learning correction coefficient, the primary diagnosis of the presence or absence of abnormality in the fuel system, and if the diagnosis result indicates that there is abnormality, the fuel system is diagnosed based on the total value of the learning correction coefficient and the air-fuel ratio feedback correction coefficient. The presence or absence of an abnormality is secondarily diagnosed, and when it is determined that there is an abnormality again, it is finally determined that there is an abnormality. Therefore, as shown in FIG. 5B, even if the feedback correction coefficient greatly changes due to the purge control at the time of light load, the learning correction coefficient, which is the abnormality diagnosis parameter of the primary diagnosis, does not fall below the rich-side determination value. The primary diagnosis does not determine that there is an abnormality. As a result, it is possible to avoid erroneous diagnosis of a temporary disturbance in the air-fuel ratio due to purging of the fuel evaporative gas or the like as an abnormality in the fuel system, and it is possible to perform highly reliable fuel system abnormality diagnosis.

In the present embodiment, the sum of the learning correction coefficient and the feedback correction coefficient is used as the abnormality diagnosis parameter for the secondary diagnosis. In consideration of the deviation amount of the actual air-fuel ratio, the total value of these three may be used as an abnormality diagnosis parameter for the secondary diagnosis to determine whether there is an abnormality in the fuel system.

In this embodiment, at the time of the secondary diagnosis, the presence or absence of an abnormality is determined based on whether or not the total value of the learning correction coefficient and the feedback correction coefficient is outside a predetermined range. And the feedback correction coefficient may be separately compared with a determination value, and the presence or absence of an abnormality may be determined based on the comparison result.

In the abnormality detection program shown in FIG. 2, after the count value of the warm-up counter exceeds a predetermined value (after engine warm-up is completed), primary diagnosis is performed until an abnormality is detected (or until operation is stopped). Although the count values of the abnormality counter and the secondary diagnosis abnormality counter are not reset, the count values of the primary diagnosis abnormality counter and the secondary diagnosis abnormality counter are reset at predetermined time intervals during operation, and the primary values within the predetermined time period are reset. The primary diagnosis may be performed based on the count value of the diagnosis abnormality counter, and the secondary diagnosis may be performed based on the count value of the secondary diagnosis abnormality counter within a predetermined time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of processing of an abnormality detection program;

FIG. 3 is a flowchart showing a processing flow of a normality detection program;

FIGS. 4A and 4B are time charts showing the behavior of each operation parameter when the purge control of the fuel evaporative gas purge system is performed when shifting from the steady state to the deceleration state.

5 (a) is a time chart showing the behavior of a conventional fuel system abnormality diagnosis performed under the operating conditions of FIG. 4, and FIG. 5 (b) is a time chart of FIG.
Time chart showing the behavior of the fuel system abnormality diagnosis of the embodiment of the present invention carried out under the following operating conditions

[Description of Signs] 10 ... Air flow meter, 11 ... Engine (internal combustion engine), 14 ... Intake air temperature sensor, 17 ... Intake pipe pressure sensor, 20 ... Fuel injection valve, 24 ... Crank angle sensor, 26
... exhaust pipe, 27 ... catalyst, 28 ... broadband air-fuel ratio sensor, 2
9 ... Oxygen sensor, 30 ... Engine control circuit (air-fuel ratio feedback means, learning means, fuel injection control means, abnormality diagnosis means), 37 ... Warning lamp, 38 ... Water temperature sensor, 40
... Fuel tank, 42 ... Canister, 44 ... Purge pipe,
45: purge control valve, 46: fuel evaporative gas purge system.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Mukai 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (reference) 3G084 BA11 BA27 DA27 EB12 EB17 FA02 FA07 FA10 FA11 FA20 FA29 FA33 FA38 3G301 HA14 JA08 JB09 ND02 ND17 ND22 ND25 ND40 NE23 PA01Z PA07Z PA10Z PA11Z PD03A PD03Z PD04A PD04Z PD09A PD09Z PE01Z PE03Z PE08Z

Claims (3)

[Claims] 1. An air-fuel ratio feedback means for setting a feedback correction amount for performing feedback control of an air-fuel ratio of exhaust gas of an internal combustion engine (hereinafter, referred to as an “actual air-fuel ratio”) near a target air-fuel ratio. Learning means for learning the deviation amount of the actual air-fuel ratio and updating and storing the learning correction amount;
Fuel injection control means for controlling the fuel injection amount using the feedback correction amount and the learning correction amount, and abnormality diagnosis means for diagnosing the presence or absence of a fuel system abnormality based on the feedback correction amount and the learning correction amount In the fuel system abnormality diagnosis device for an internal combustion engine, the abnormality diagnosis means performs a primary diagnosis on the presence or absence of an abnormality in the fuel system based on the learning correction amount, and performs the learning when the diagnosis result indicates that there is an abnormality. A secondary diagnosis of the presence or absence of an abnormality in the fuel system based on the correction amount and the feedback correction amount, and finally, when it is determined that there is an abnormality again, the diagnosis of the presence of the abnormality is finally determined. For diagnosing fuel system abnormality of internal combustion engine. 2. The abnormality diagnosis means sums up the learning correction amount and the feedback correction amount when performing secondary diagnosis of the presence or absence of a fuel system abnormality based on the learning correction amount and the feedback correction amount. 2. The fuel system abnormality diagnostic device for an internal combustion engine according to claim 1, wherein a secondary diagnosis is performed for the presence or absence of an abnormality in the fuel system based on the total value. 3. The abnormality diagnosis means accumulates the time during which each abnormality diagnosis parameter is out of a predetermined range during the primary diagnosis and the secondary diagnosis, and diagnoses that there is an abnormality when the accumulated time reaches a predetermined time. 3. The method according to claim 1, wherein
A fuel system abnormality diagnostic device for an internal combustion engine according to claim 1.