Hi everyone!

I just had a compression test done at my local Mazda dealer and got some results i can't really wrap my head around. The readings were taken at sea level and read directly off the OEM Mazda compression tester and not through the USB.

Front rotor @ 182rpm
5.3
5.6
6.1
x 100 kPa

Rear rotor @ 184rpm
6.0
6.0
5.9
x 100 kPa

Rear rotor as far as i can tell is doing good however the front is looking a little worse for wear. However this test was done with a bad battery and probably a gen 1 starter witnessed by the very low crank rpms.
The car starts right up cold and only takes a bit longer while warm with the same battery and starter. Uses normal amounts of gas. And objectively has great power. Engine was replaced with a Mazda reman 31k miles ago.

Is there a possibility that the results are skewed to look worse than they are or is my relatively fresh engine dead already?

 

the compression #s should be adjusted for the 250rpm cranking iirc

 

When normalized to 250 rpms with the foxed.ca calculator the readings are still not in my favor. However i still wonder if the low crank rpms may have impacted the readings in such a way that the numbers are useless? I cant find many posts about people having their tests done at low crank rpms. I would do another test with a fresh battery but the test is quite frankly too expensive where i live.

 

if normalized and the #s are still below the threshold its most likely low comp. 31k isnt unheard of for an engine to crap out. was it a reman? if not who rebuilt it? what parts were replaced? housings?

 

Well now im sad

Was really hoping the numbers were skewed because of how healthy the engine seems in general. I actually took a compression test to confirm how good it was but it turned out to be the opposite.

 

So it sounds like you don't have any actual problems?
I'd put the upgraded starter model on it l and continue enjoying. Maybe retest in some while.

Not that you shouldn't trust the results but like anything, there can be outliers. I had 1 comp test show failing in 2014 and not ever since then.

 

Your compression #s appear fine ...after 30k+ mi. and viewed wrt rpm. If difficulty starting as has been recommended... upgrade your starter, and, if you don't already, premix.

Happy rotarying.
.

 

Sounds like i should just disregard the numbers and just enjoy the car while it lasts
I think i'm going to do that.