Mike T wrote: That is good information! Thanks for it but this is an older model there is no wires going to the injectors the injectors are fired off of pressure.
You could scope the cam and/ or crank sensor signals, then you would have a known good for the future. I'm not sure how much more there is to look at on those older engines.
This is a screen shot of one of my other dodges it’s a 2002 Dodge Ram 3500. 5.9l 24 valve second gen and it’s not inverted either but now I’m confused. What way is up?
here is one of my 2011 Ford F-150 5.0l
It all look right but I could have filtered it and inverted my coil but it’s right. Right? Lol I have done a few different tests this was my first one with amp clamp and and it was on backwards I thought. And I didn’t ac couple this one. So should I ac couple? Sorry For so many questions
AJeep18 wrote: not that it is really any easier than using the invert function, but could one just switch the test leads around also?
Yes, you can reverse the leads to invert the waveform. That is how I do it with the Pico. But, know your scope. If your scope shares a common ground with all channels, (and Snap-on does), then you may run into some unexpected results. :woohoo: With Snap-on, I would recommend using the Invert function.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
These are the settings I used and the capture I got on a 6.7 Cummins with a bad cylinder, black lead on ground yellow lead on the positive battery cable
i dont really use the guided one. well i do sometimes but alot of time i just try to figure out the right settings so im use to it if there isnt a guided test. but i still use it to try and get the right idea the first time i test something. i guess i should use it more so i dont have to bug you so much lol
Did you see that picture i put of my 2002 dodge the compression looks so close that it looks right side up and its not inverted the spikes across the bottom of the screen witch should have been the top are straight across... lol
Hi Mike,
It looks as if you did use a voltage scale on your 2002 Dodge and that is how it should look normally. As the starter is cranked, the voltage load on the battery drops as a cylinder hits it's compression stroke and then comes back up until the next cylinder hits compression when it will drop again and so on until you stop cranking. There is actually no need to invert your pattern because that WOULD make the result confusing. Also, unless there is an uneven cranking rhythm (like in your capture of the other Dodge), I would not be too concerned with trying to find a way to synch your capture with something. At some point in the past, I thought Snap-on had a way to synch a diesel by means of clamping some device connected to your scope to a diesel injector tube.
I hope this helps. Take care,
DougS
DougS wrote: At some point in the past, I thought Snap-on had a way to synch a diesel by means of clamping some device connected to your scope to a diesel injector tube.
There are several companies that make diesel pulse adapters for use with 'scopes and timing lights. They detect the injector pressure pulse in the line going to an injector. So they probably won't work for a relative compression sync with fuel disabled.
Could pull a glow plug and use an in cylinder transducer if you want a sync badly enough...
Sorry, Mike, but my last reply won't work because of disabling the fuel system. :pinch:
A pressure transducer would work (as long as it's rated high enough for diesel compression pressures).
DougS.
Last edit: 3 years 2 months ago by DougS. Reason: Addressed to wrong person
:pinch: