[2009 Nissan Versa 1.6, Tailpipe Pressure During Misfire Photo]

O.K. guys, this is a waveform of an an ignition misfire while monitoring tailpipe pressure. Below is my theory of the waveform. Im still new to using a pressure transducer so any feedback would be appreciated.

The blue trace is the tailpipe pressure during an ignition misfire. The red trace is the ignition sync for the misfiring cylinder. During the misfire, the combustion process does not take place. After the expansion stroke a vacuum is created prior to the exhaust valve opening. When the exhaust valve opens, this vacuum/low pressure escapes into the exhaust system. Inside the cursors are approximately when the exhaust valve opens. You can see the blue trace drop in pressure. The bottom waveform is known good. Hope you enjoyed!

Michael Seaman
Technician
Quality Truck & Auto
Hillsborough, New Jersey, USA

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