Newbie having problems

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any chance the valves clearances need adjusting, it would be unusual that all 4 cylinders are out

 

[Paulsw55]

Testing Compression relies on good battery voltage throughout the test and good starter performance for cranking speed. Compression ratio of 15:1 times Atmospheric 14.7 PSI = 220 psi on a good day with swift cranking . as battery volts go down and cranking speed goes down ,cranking pressure will go down . i am always careful of compression results that drop as test continues. Sensors may not be working as they should but still in parameters called for by computer thus log no code . the reader used needs to be able to read the real time pattern of the sensors to determine signal form and cam and crank sensor timing to determine timing chain condition.first I would check battery voltage while cranking. cranking speed is critical for electronic system to start up. if cranking slower wont go. Need someone with a real time reader that knows how to use it while the engine is running.

 

[Old.Tony]

^ I can't argue with your math, even if you have to add another atmosphere for "natural" pressure. The manual defines things differently though - not sure why, but their PSI recommendations are much higher.

From the manual: tested at 200rpm:

Standard compression 406psi
Minimum compression 319psi
Maximum variance 65psi

This is the newer YD25 with a 15:1 compression ratio, the older YD25 like mine runs at 16.5:1 (with higher compression limits than above).

 

[Andyjo]

I'll chuck in my penniths worth, fit a temp clear plastic line between the filter and pump, if its an air problem you'll see it.
Blank off the EGR, even if its not the source of the problem (and could be), the engine will benefit from not having exhaust fed into the intake.