Leak and blockage diagnostic systems and methods

Abstract

A diagnostic system for a vehicle is disclosed. A first difference module generates a first difference based on a first pressure measured at a first secondary air injection (SAI) valve and a previous value of the first pressure. A first summer module generates a first accumulated difference based on a sum of values of the first difference generated during a predetermined period. A second difference module generates a second difference based on a second pressure measured at a second SAI valve and a previous value of the second pressure. A second summer module generates a second accumulated difference based on a sum of values of the second difference generated during the predetermined period. A fault indication module selectively indicates that a fault is present downstream of one of the first and second SAI valves based on the first and second accumulated differences.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Application Serial No. 61 / 716,055, filed October 19, 2012. The disclosures of the aforementioned applications are incorporated herein by reference in their entireties. technical field [0003] The present disclosure relates to internal combustion engines, and more particularly to diagnostic systems and methods for vehicles with two secondary air injection valves. Background technique [0004] The background description provided herein is for the purpose of generally presenting the context of the disclosure. The work described by the inventors in this Background section and aspects that are not described as prior art at the time of filing are neither expressly nor impliedly admitted to be prior art that conflicts with the present disclosure. [0005] The engine combusts an air / fuel mixture to produce drive torque for the vehicle. Air is drawn into the engine thro...

AI Technical Summary

Problems solved by technology

However, when the temperature of the catalyst is lower than the predetermined light-off temperature, the catalyst may not respond

Therefore, when the catalyst temperature is likely to be less than the predetermined light-off temperature, the responsiveness of the catalyst may be limited briefly after the engine is started (eg, key-on)

Images