Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Okay on the scope I was marking it with the #2. if you look at it, it looks to me that the #1 has the bad cylinder. But the compression is good. I unplugged to coil on number 1 and no change. But when I did compression on the number 2 it was zero! I new it had to be one of them cylinders but I was sure it was number one by looking on the scope but turned out to be #2. Firing order is same as chevy small block 18436572
So on your waveform, where the #2 ignition sync is showing on the capture, it looks like it matches up with the low cylinder, which would show me that it is indicating a problem with the #2 cylinder. Sometimes the ignition timing for cranking in relation to the relative compression waveform on the scope can make it appear that the firing event is happening late or not close to TDC as you might expect, but that spike shown in your capture is still happening in that low cylinder on the pattern, and so with that being the #2 that you had synced the waveform to, that is definitely occurring in the #2 compression event. So since you rechecked compression on that #2 cylinder and found 0 PSI, have you done a leak down to verify what exactly is not sealing?
The way the wave form just looks like one spike and a bigger spike then the others made me think the valves stuck or something to make it draw more amps. But it was the number 2 so I see what your saying.
No I haven’t. As soon as i told them one cylinder had no compression that was good enough. They won’t replace the head or head gasket. I probably should have kept going I wanted to use the scope to do a few other things on it to just don’t have time really.
