06/03/2021
This 2007 Mountaineer had a misfire with no related fault codes. We were able to identify the misfiring cylinder using tailpipe pressure. The first photo shows the abnormal waveform with the exhaust pressure pulses.
The anomaly in the waveform is seen where one pulse is much lower then the rest. If we look at the overlay during this event, we can see this is occurring during cylinder # 8 exhaust valve opening.
This low pressure drop is cause from a lack of combustion.
Now that we know there is a misfire on # 8 cylinder we can start by checking our ignition. The second photo shows an ignition related misfire from a faulty ignition coil.
