hi all, i have had a merc ml320 in the workshop with a misfire, scanning logged cyl 2 and 5 misfire detected, with the vehicle having plug leads i thought for good practise i wanted to analyse the secondary pick ups, cylinders were rigged up as follows:
cyl 2 blue
cyl 5 red
cyl 1 green (supposed good cylinder)
cyl 4 yellow
i could not pick up anything like what i have seen in the library and my course notes, noted blue and red are different to the other two, i did swap over the coil packs to see if there was any change, no change.
The outcome of the misfire was low compression on cyl 2 and 5, vehicle is off to the breakers i believe.
Just wanted the experts to analyse what i found, am i seeing a poor burn due to low compression or have i rigged the scope wrong.
Your correct with firing order, I think I made some hash up with the set up, I thought the vehicle had disapeered but it us still in the workshop (customer was meant to pick up vehicle sat morning but was there when i popped in at midday).
I'll get in early Monday morning and rescope secondarys in firing order, will admit I was just concerened with the waveforms not looking like what I've seen before.
Will post a better set up as I think I've got some wires crossed somewhere. Cheers for the help on this thus far.
Cheers for showing the notes section, i am so used to relying only on my short term memory for everything and lately it has gone south,, will make solid notes from now on.
antthecat wrote:Cheers for showing the notes section, i am so used to relying only on my short term memory for everything and lately it has gone south,, will make solid notes from now on.
I like to capture primary Volts on these coil near plugs because burn time is the most important part of the wave.
If you do capture Primary Volts please attach the attenuators on each channel and select the Pico custom probe of it.
This gif shows a fault in the B side of the coil which caused quite the misfire.