Patent ID: 9618423
Date: 2017-04-11
CPC Classifications: B60W,F02D,G01M

Claim:
1. A system for misfire diagnosis of a vehicle engine, the system comprising: an angular velocity sensor acquiring an angular velocity of the engine; an acceleration sensor acquiring an acceleration according to vertical vibration of a vehicle; a diagnosis unit configured to compare the acceleration with an acceleration threshold to determine whether the vehicle is driven on a rough road and configured to diagnose whether misfire occurs in the engine based on whether the vehicle is driven on the rough road and a variation of the angular velocity; and a threshold setting unit configured to acquire misfire diagnosis results from the diagnosis unit in a first test environment in which the vehicle is driven on the rough road without forcible misfire and in a second test environment in which the vehicle is driven on the rough road while the forcible misfire occurs in at least one cylinder of the engine, configured to calculate a misfire misdiagnosis rate according to misfire diagnosis results in the first and second test environments when the forcible misfire occurs, and configured to update the acceleration threshold so that the misfire misdiagnosis rate has a value that is smaller than a target value.