Secondary Air System Diagnostic Test Phases
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Solution Overview
Problem
Diagnostic testing of secondary air systems is challenging due to the complexity of identifying failed or incorrectly installed components, as the systems involve multiple junctions, hoses, vacuum, hydraulics, and electronics, making it difficult to determine the specific issue or incorrect installation during assembly.
Innovation Solution
A diagnostic test is developed comprising multiple phases with specific delay and testing periods, using mass air flow sensors to record air flow and compare it to predetermined characteristics, incrementing fail counters for inconsistencies, and combining results to identify potentially failed or incorrectly installed components, which can be matched to specific components in the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple junctions, hoses, vacuum, hydraulics, and electronics are used in the secondary air system, then the system functionality is improved, but the difficulty of detecting and measuring component failures increases
Solution Approach 1:
The diagnostic test segments the secondary air system into distinct functional phases (first testing phase with pump activation, second testing phase with check valve opening, third testing phase with check valve closing, fourth testing phase with pump deactivation). Each phase isolates specific components for testing, allowing systematic identification of failures in complex systems with multiple junctions, hoses, vacuum, hydraulics, and electronics without requiring complete system disassembly or complex diagnostic equipment.
2Measurement precision
If a comprehensive diagnostic test with multiple phases is implemented, then the precision of component identification is improved, but the time required for testing increases
Solution Approach 1:
The diagnostic test employs periodic action by cycling through four distinct testing phases in sequence, with each phase activating specific components (air pump, check valves) for a predetermined period. This periodic activation pattern allows comprehensive component identification by observing system behavior at different operational states, achieving high precision in locating failures while maintaining reasonable testing time through structured, repetitive test cycles rather than continuous monitoring.
3Measurement precision
If fail counters are incremented for each testing phase inconsistency, then the accuracy of failure mode determination is improved, but the complexity of data processing increases
Solution Approach 1:
The diagnostic system implements feedback by incrementing fail counters for each testing phase where measured air flow deviates from expected characteristics. This feedback mechanism accumulates diagnostic information across all four testing phases, with each failed check or inconsistency contributing to the overall failure mode determination. The systematic feedback approach enables accurate failure identification through simple counter incrementation and comparison against predetermined operating characteristics, avoiding complex data processing algorithms.
Data Source
AI summary
A diagnostic test for a secondary air system comprising an air pump, a first mass air flow sensor connected to the air pump and a first check valve connected to the first mass air flow sensor. A first testing phase is disclosed comprising a first delay period and a first testing period, wherein the air pump is activated. A second testing phase is disclosed comprising a second delay period and a second testing period wherein the first check valve is opened. A third testing phase comprising a third delay period and a third testing period is disclosed wherein the first check valve is closed. A fourth testing phase is disclosed comprising a fourth delay period and a fourth testing period wherein the air pump is deactivated. An optional fifth testing phase is also disclosed comprising a fifth delay period and a fifth testing period wherein the air pump remains off but the check valve is reopened and engine RPMs are increased. The diagnostic test further includes determining one or more failure modes of the system based on the output from the four or five testing phases.