junk burn from misfire due to no spark

[mwebb]

using a pizeo type differential pressure sensor in the exhaust
green trace

at idle
blue trace is spark from a 4 in 1 coil pack , 1 coil is not outputing any secondary spark as seen in the waveform by 1 missing spark signature every 4 spark events -
note
in the exhaust after the combustion event that did not happen
there is an increase in pressure as the fuel that did not combust , burns in the hot exhaust along with the 02 that was not combusted in the combustion event that did not happen .
junk burn , injector is working .

another way , change in crankshaft speed as measured by alternator out put , read text bubbles
the image above was culled from the image below , what you thought was "alternator ripple " is really change in alternator output due to variation in crankshaft speed

think out side the box -

[drmiller100]

or just plug in an obd2 scanner and it will show misfire on the offending cylinder.

[Tygen1]

mwebb, you are one of my favorite contributors!

[mwebb]

Originally Posted by drmiller100

or just plug in an obd2 scanner and it will show misfire on the offending cylinder.

if you have the OBD2 scan tool with ENHANCED capability s you might be able to use or view misfire counters , but even if you could get a
p030X (where X is the # of the misfiring cylinder ) from the generic tool
all you would see is the Scan Tool's interpretation of the data it is presented
you would NOT know the actual cause of the misfire.

assuming
you have a scan tool for you particular application and
assuming you have a later OBD2 system as the earlier systems did not report the correct cylinder if it would report anything other than
p0300 , random misfire .

anyway
ENHANCED scan tools can be a part of the solution
many times
but
not always

most Generic OBD2 scan tools are pretty useless , except ESCAN

enhanced scan tools that can graph and log paired with high resolution scopes are the answer , imho