Ignition coil guided component tests.

Hello guys and girls. I am working on a 2003 Volvo XC70 with a misfire under load and a little roughness at idle. My problem is I cant get a good waveform from the coils using a paddle probe. So I decided to see what the Snap On guided component test had to offer. It tells me that I can do a freq. and duty cycle test. The Freq test says at idle it should be between 5 to 7 Hz with no dropouts or glitches during test. On all coils I have both dropout and glitches at idle and 2500 rpm. I am not sure why. Can anyone tell me? I checked the coil control voltage and have No dropout but brings me to my next question. The turn on signal is not a true 0-5v square wave like I am used to seeing. It goes from 0 to 2.7 with the turn on rising straight up to 1.9v then rounding off to 2.7v with about a 2ms time. Any help with either problem is appreciated.
How do I upload a file from shop stream connect?
If this post is in the wrong section please feel free to move it.

Hey john! Unfortunately the forum software won't allow direct uploading of ShopStream data files or scope captures. I've been taking screenshots and editing them in Paint instead. Or, I've been trading e-mails and sharing files that way! I'd be happy to look at your captures. wrenchturnsyou@gmail.com

The coil control waveform you described sounds pretty normal, IMO. It's typical of a three wire coil design used by Honda, Nissan and others. I know your Volvo coils have four wires, but one is really just a secondary ground circuit. That 'ramp' is a product of the transistor inside the coil itself. The signal generated by the PCM is actually 0-5V, but becomes a ramp when current starts flowing through the transistor inside the coil. This video goes more in-depth if you're interested:



As for the frequency test... I'm not sure? :huh: I've never done that particular test on a COP before. This may be an unpopular opinion, but I'm really not a big fan of the Graphing Multimeter. :blush: Do you have access to trouble codes? I'd probably try swapping coils around first, just to see if the code and miss move. You can do a quick power balance test to check cylinder contribution at idle. If you suspect a coil, you can also use a test light to check spark strength out of each coil, and see if you have a weak one.