New answers tagged compression
I did some searching on IATN and found known good pressure waveforms that are identical to my after repair captures. Unfortunately I can't post them here. It turns out that hump is completely normal. After doing more captures on different cars with VVT I've found that most waveforms are unique to some degree. I guess the same can be said about non VVT ...
TL;DR: Either there's a problem with the head gasket, or with the piston rings. Remember, the piston rings fly over the openings in the cylinder wall, and there's no radial force onto the section exposed to the opening, pushing it into its groove. Shortly after, this section touches the cylinder wall again and experiences the radial force pushing it back. ...
Those numbers do not seem horrible, unless the 140psi is low. You might want to repeat the test with the engine warm. I generally feel that a cold test only reveals inter-cylinder differnces (in your worst case only 18psi), but dynamic compression after everything is warmed up and expanded might be much better.
Yes, it does lead to a loss of a power, but your compression is not worth worrying about. Every engine will loose some compression after a few years. New rings wear out faster at the beginning and later they wears out slowly, so probably you won't see a difference for another 2 years.
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