Be sure and test on a known good vehicle. Woops

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Mitchroberson
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Joined: Mon May 09, 2022 1:09 pm

Be sure and test on a known good vehicle. Woops

Post by Mitchroberson »

I may need a bit of help. I received my pico scope. And of course I wanted to be sure and run some tests to start to learn how to use it. This test will be on a 2014 Chrysler Town and Country, With the 3.6 l pentestar engine. Well that did not go as planned. In the first screen show you can see the Picodiagnostics Compression test showed a low cylinder. Now some history on this vehicle. it had the infamous rocker arm tick. Needless to say we kept driving it.
Eventually it stopped in the middle of the road. It was toed in. And a broken valve spring on cylinder 3. Rockers were replaced on both banks as well as the broken intake spring on cylinder 3, New intake cam shaft on bank 2 And timing gears and chain were installed. All codes cleared and vehicle has been running very well ever since.
Now we were thinking about taking the car on a long trip it has 190K miles on it. And I thought it would be good to learn some new skills will prepping the car for this trip.
Now that we have the relative compression test. It is time to pull one with a signal. This was done with cylinder 2 as the signal.
Now you can see there is something odd about this trace. As we have 3 cylinders that are low. These are all bank 2 cylinders. Hmmm car runs very well at this point and time it is slightly rich. so Long Term fuel trims show -10% both banks so not sure this is related.
so I wanted to try to find the exact problem with out pulling the manifold off. And I wanted to see what I can find with pulse sensors. So I have attached 2 different screen shots with intake pulse and cylinder 2 coip. And then another with cop, intake and exhaust.
Thinking I need to do cam correlation with bank 1 and bank 2 next. And feel like the Intake wave form is off.
Attachments
ChryslerTAndCVaccumAndExhaust.PNG
chryslerTAandCIntakeVacuum.PNG
ChryslerTANDCRelativeCompression.PNG
ChryslerTandCCompressionPdiagCapture.PNG

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