Exhaust Camshaft Timing Errors

Exhaust cam is very advanced. As the piston rises on the exhaust stroke, the ex valve closes early which traps some spent exhaust gases. This causes the pressure to rise as the piston is rising on the exhaust stroke. Hence the pressure spike near the 360 deg mark. As soon as the intake valve opens the pressure in the cylinder drops. If there were a transducer in the intake you would see a

Thanks for chiming in here Bob. Yes you're right and as you can see we didn't have a sample signal in the intake but I wish we would have. However I believe that in some cases this intake signal disruption might be hard to see depending on manifold design. One thing here that I wanted to emphasize is that we performed the relative compression test and failed to recognize the small bump in this

I understand. I have been know to miss little details like that when I'm in a rush to get the work out the door and I don't take the time to "analyze" my test results.