To provide a method and device for diagnosing an internal combustion engine, that suppress ill influence to an ignition plug or an exhaust gas purifying filter when diagnosing presence or absence of a cylinder whose air fuel ratio is abnormal.
According to this method and device 14 for diagnosing the internal combustion engine, any one of a plurality of cylinders 32 whose air fuel ratio is abnormal is identified during the engine 16 being in operation. The engine diagnosing device 14 has an abnormal cylinder identifying part 84 to identify the abnormal cylinder from the relation between the air fuel ratio changed in steps and the frequency of misfire occurrence of each of the plurality of cylinders 32, and a protection part 84 to protect the ignition plug 36 or the exhaust gas purifying filter 18 by interrupting the step-by-step changes of the air fuel ratio in case the frequency of misfire occurrence of any cylinder 32 or the sum total of them has exceeded a prescribed level during the air fuel ratio being changed in steps.
ABE TAKAYUKI
KATO MASAHIRO
ONO TETSUYA
| JP2010112244A | 2010-05-20 | |||
| JPH08144832A | 1996-06-04 | |||
| JP2009270543A | 2009-11-19 | |||
| JPH03189371A | 1991-08-19 | |||
| JP2009299662A | 2009-12-24 | |||
| JPH10176565A | 1998-06-30 | |||
| JP2010112244A | 2010-05-20 | |||
| JPH08144832A | 1996-06-04 | |||
| JP2009270543A | 2009-11-19 | |||
| JPH03189371A | 1991-08-19 |
| WO2012029517A1 | 2012-03-08 | |||
| WO2012029517A1 | 2012-03-08 |
Toshiyuki Miyadera
Shuji Ouchi
Next Patent: METHOD AND DEVICE FOR DIAGNOSING INTERNAL COMBUSTION ENGINE