# Automatic Failure Modes and Effects Analysis of an Electronic Fuel Injection Model
## 4 Case study: Electronic Fuel Injection System
### Electronic Fuel Injection Analysis Using Automatic FMEA
#### 4.2.3 Step 3: Failure Effect Identification  
In this step, we build the rule base to identify the failure effects of the target Simulink model to analyze the failure effects and the severity of the FMEA using the results of the fault injection campaign. The automatic FMEA user prepares failure effects' determination rules according to the three-step procedure. The first step is to determine the type of the failure effect. When a system failure occurs, a target function may halt its execution, or an unexpected malfunction may occur. All malfunctions in the fault simulation are recorded as files. Among these malfunctions, those related to safety are collected as candidates for the next step. The second step determines the output value of the selected candidates to analyze the failure effect. The analyzer identifies the output of the model related to the failure effects  
Finally, to assess the severity, the allowable range of data is determined. Automatic FMEA analyzes the failure effect by comparing the normal value and the failure value. The user analyzes the failure effects by presenting an acceptable range of failure values in a quantitative manner. Note that the occurrence of the FMEA can be identified using a similar rule-based system and fault tree analysis to calculate the failure rate for each failure mode. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Test Scenario**} & \multicolumn{2}{c}{**Operation Mode**} & \multicolumn{2}{c}{**Vehicle Information**} & \multirow{2}{*}{**Distance**} \\  & **Start Time** & **End Time** & **Velocity** & **Acceleration** & **Distance** \\ \hline Acceleration Test & 0 & 100 & 30.6 km/h & 0.31 km/s\({}^{2}\) & 850 m \\ Cruise Test & 100 & 505 & 32.2 km/h & 0 km/s\({}^{2}\) & 4475 m \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Operation modes and vehicle information for the test scenario. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Sensor Failure Mode**} & \multicolumn{2}{c}{**A-FMEA Failure Mode Condition**} & \multirow{2}{*}{**Time (s)**} \\  & & **Fault Type** & **Value** & **Value** \\ \hline
1 & Drift fault 50\% & Less than requested & V\({}_{\text{out}}\) = V\({}_{\text{Normal}}\)\(\times\)\(\alpha\), \(\alpha\) = 0.5 & 505 \\
2 & Drift fault 150\% & More than requested & V\({}_{\text{out}}\) = V\({}_{\text{Normal}}\)\(\times\)\(\beta\), \(\beta\) = 1.5 & 505 \\
3 & Hard-over & More than requested & V\({}_{\text{out}}\) \(\geq\) V\({}_{\text{MAX}}\), V\({}_{\text{MAX}}\) = 1.0 & 505 \\
4 & Stuck 0 & Locked/stuck function & V\({}_{\text{out}}\) = V\({}_{\text{Const}}\), V\({}_{\text{Const}}\) = 0.0 & 505 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Sensor subsystem failure mode table. We now explain the rule-building process with the EFI Simulink model. In this section, we explain the sensor failures in the EFI model causing the (1) engine stop, (2) engine hesitation, and (3) gas mileage reduction. First, the engine stop occurs when the fuel cannot be injected into the cylinder due to a stuck failure of the EFI sensors. If the engine stop failure occurs while driving the vehicle, the driver cannot control the vehicle, and the risk of an accident is high. When an engine stop failure occurs, the engine RPM value is reduced to 0. Therefore, we may build a rule for the engine stop failure effect with the condition part as the conjunction of the vehicle is running, and the engine RPM value converges to 0, which is Rule 1 in Table 5. As shown in Table 5, the failure mode category is a specific failure condition check where the condition part of the failure diagnosis rule is \"Engine RPM == 0\". If this condition is met, we set the severity to 8. Second, the engine hesitation failure effect may occur when the amount of fuel injected into the cylinder fluctuates due to a drift failure of the EFI sensor unit. The engine hesitation may cause noise and vibration while driving the vehicle, and may be regarded as a potential threat for the driving safety.