Title:
TROUBLE SHOOTING DEVICE FOR SECONDARY AIR SUPPLY
Document Type and Number:
Japanese Patent JPH05256127
Kind Code:
A
Abstract:
PURPOSE:To provide accurate trouble shooting for a secondary air supply even if an engine is in such a drive condition that the great effect of exhaust pulsation is given to a secondary air supply passage. CONSTITUTION:In case that an air control valve 23c for a secondary air supply 23 is diagnosed to break down, a breakdown criterion is changed with the magnitude of exhaust pulsation in an exhaust passage 10. By comparing a feedback correcting coefficient based on a detection signal from an O2 sensor 27 arranged in the exhaust passage 10 with the changed breakdown criterion, secondary air is detected to leak or not from the air control valve 23c during non-supply operation, to judge the air control valve 23c to break down. In this way, diagnostic error resulting from the effect of exhaust pulsation in the exhaust passage 10 is prevented.
Inventors:
Murata Shoji
Application Number:
JP5236192A
Publication Date:
October 05, 1993
Filing Date:
March 11, 1992
Export Citation:
Assignee:
Mazda Corporation Inc
International Classes:
F01N3/22; F02D41/14; F02D45/00; (IPC1-7): F01N3/22; F02D41/14; F02D45/00
Attorney, Agent or Firm:
Hiroshi Maeda (2 outside)