secondary waveform

Hello. This waveform is on a hyundai 2.0. Dead misfire. This is a secondary ignition waveform. everything looked good, but noticed the hashy line on the fire line. So i did a compression check on that cylinder and it came out to 45psi. I hope i made the right call on this. The hashy line on the fire line is it suppose top be a good indication of a in cylinder problem? 

IS there anybody that can point me in the direction on this?

When you say hashy, do you mean this part at the end of the burn line?

 

These are normally called coil oscillations. I've always been told they're the result of left over energy bouncing around in the coil. The presence of the oscillations is actually good thing - missing oscillations would be a red flag.

I'm talking about this. The cylindar i took this on had low compression about only 45psi. Let me clarify my question im trying to find out if there is a indication on the waveform to suspect low compression. 

I gotcha, thank you for clarifying!

Let me clarify my question im trying to find out if there is a indication on the waveform to suspect low compression. 

For me? Not a ton. Sometimes, the slight downward slope of the burn line can be indicative of a low compression or rich condition? But I find that to be dependent on the secondary probe and where it is on the coil.

But let me say that, in my opinion, secondary ignition is not always great for identifying low compression concerns. Not to say that it can't be used for that, just that it takes lots of practice and careful comparison with known good cylinders. Not to say you were wrong for looking at secondary ignition, either. I'd have done the same.

There are a couple other things you can look for with low compression cylinders. One would be the height of the firing line, compared to known good cylinders. Normally, cylinders with low(er) compression have a noticeably lower firing line. Again, this can be tough to pick out depending on the probe and where the probe is on the coil.

Another would be to look for turbulence in the firing line during a throttle snap. This is probably closer to what you were told to look for. Hash in the firing line is usually a good indicator of cylinder turbulence, generated by compression. No turbulence would suggest low compression, or spark occurring outside the cylinder.