Delta Pressure pulse sensor analysis jeep running rough

keep Cherokee 2010 V6 running rough and no start.
tools used on making this video
pressure pulse sensor ebay.us/ekGK7a
cylinder leak down tester ebay.us/dRUUix
amp clamp ebay.us/bXgdyh
this video will demonstrate how we can identify
compression problem along with identifying which cylinder is at fault and then diagnosing valve sealing issue without even taking any parts of the engine simply using oscilloscope and accessories.
it's a very common issue with Jeep Cherokee. the lifters for rockers go bad and rockers fall of the cam lobe.
pressure sensor type diagnosis is very handy skill to learn to save time and have confidence in identifying mechanical issues with engines.
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[@shakeelsss]

Thanks a ton forthis educational video. I finally understand how to read the intake pulse chart.

[@duanedonaldson2262]

You should not be syncing your chart off from the spark event, that happens before TDC on a Petrol engine, you should sync your chart closer to TDC on the intake vacuum pulse waveform, not super important here based on a smooth waveform but in a more realistic waveform, it will show some problems more efficiently. For your Delta tester, your soft rubber hose is way too long and too soft, I know the Delta tester needs to hang away from a bouncing engine but you can still hang the sensor with a shorter or stiffer hose for a more realistic pressure pulse which ought to have smaller spikes or rounded sections, not so clean like your 4 cylinder picture. As you can see, the actual vacuum pull for each cylinder is actually only the first half of the blue INTAKE section or 90 degrees of crankshaft rotation, other factors affect the waveform to include piston speed and valve overlap (where this chart ought to be aligned just a little more to the right) as both of these can be seen in this waveform. If you look at the section of the Delta wave as the pressure is increasing, the first half of the increase is at an angle, then all of a sudden it increases more vertical, this is where the intake valve opened allowing exhaust gas to enter the intake manifold during valve overlap so you can align the brown Exhaust and blue Intake border at this pressure increase transition point. These charts are not a real-world activity but they are a quick guide to point you in the right direction. Now we can see that all the borders will still not perfectly align based on other factors suck as cranking speed, timing tolerances, individual cylinder compression, sunken valves, worn cam lobes, and valve clearances. This is part of the reason to use a shorter and stiffer hose in an attempt to see more of these deviations.
When we go back to reverify the bad waveform we can see again the color chart is not exact and it also needs to be moved just a little to the left based on #2 exhaust push creating the very high-pressure pulse then the #3 intake opening which is actually just a little before TDC of the RC red waveform in the real world showing us that the chart should be over just a little to the left showing us once again that the chart is only a guide, it's up to us to make minute adjustment to our own exact needs. Why is #2 Exhaust stroke pressure increase so high if the air is escaping out of the intake and the exhaust valve while #2 compression stroke is pushing all of the air back into the intake manifold. Look at the overall chart, when #2 is exhausting out of 2 valves, at that same moment #4 is intaking but when #2 is compressing, both #1 and #6 are intaking lowering the overall Delta pressure differences and keeping the #2 compression pulse from going up off above the scope graph. Additionally, when #2 is on its Power Stroke, it is acting as an intake stroke pulling the intake manifold pressure down even move with #5. We can then see where #2 exhaust valve opens just a little to the left of the brown Exhaust section within the waveform knowing that an exhaust valve actually opens before BDC and then actual BDC is visible. Sorry for any repeats, another thumbs up.
As mentioned, no start as 2 intake pulls missing and 3 out of spec. The visual problem from about 31 to 34 minutes you are trying to prove your theory with your 6 cylinder pic taking up HALF of a screen, we cannot see the spark advance prior to TDC where the color chart black vertical lines ought to be aligned, not forgetting the color portions are off by default.
432
165 companion cylinders, Compression to TDC vs Exhaust to TDC.....Power to BDC vs Intake to BDC

[@a1mechanicaloakey639]

Thanks for the effort to write up a whole bunch.
When using delta pressure pulse sensor, also need to take into consideration of pressure reaction on return. It's like a swing. Harder you go forward, harder it will swing back or as a sports ball. Harder you hit harder it bounce back. So there is not always a definite answer for every pressure changes.

[@DJ-tn7vj]

@@a1mechanicaloakey639 too much to read

[@rdaleyj1]

Good job and instruction.

[@vincentmeadows1905]

I thought the delta sensors reading needs to be inverted when reading

[@tylerbloyd8702]

My experience with these is that most of the time this issue occurs it has dropped a valve seat.

[@DJ-tn7vj]

Thanks for the follow up on the video

[@train4905]

Superb