Can't speak with firsthand knowledge on the concept of it being impossible to get a valid compression test done on an 03 Miata - first I've heard of such an anomaly. My first Miata was a 2001 - one of the first things I did on it was a compression test (just for my own education - no issues). For the life of me, I can't remember the numbers (~ 6-7 years ago) but I do remember that I had no trouble testing dry or wet and that all four came up within a spread of less than 10 psi.
A little bit of poking about on miata.net and I've found one thread where one person says VVT makes no difference in a compression test. Makes sense to me - pretty sure the variable valve timing comes into play at RPM's well above starter motor cranking.....
A few things to ask about that may matter....
1) Was the compression test done with the throttle wide open? Not doing so will make for wacky results.
2) Was the engine warm when tested?
3) Are those numbers wet or dry? Assuming dry, what are the readings wet?
4) Any chance of getting a leak down test done?
Found three separate references to the following numbers for NB engines:
Quote:
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Standard is 209-psi, Min. 146-psi. Max acceptable difference between cylinders is 28-psi.
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1961 220b: first project car - sold.
2000 CLK 430: first modern Benz - sold.
2001 CLK 55: OMG the torque!!! - sold
1972 280SE 4.5: Baby Gustav
1991 300TE 4Matic: Gretel the Snow Bunny - sold
1978 300SD: Katz the Free Man - given away
1980 Redhead: Darling Wife
