Just got a comp. Test done at my local Mazda dealer. Tech said the motor had been replaced at 92k miles and it has 116k. So I asked to see the results and he showed me his computer readings. The original readings for the front rotor were low 6's. Highest was 6.4 @138 rpm. But he said that his boss input the wrong number and changed it to 238. Rear rotor got mid 7's all the way across @241 rpm. Is the tech allowed to change numbers??? I thought the computer was fed the readings directly from the gage???

 

I would have them re run the compression test. Low 6's is a failing motor. I would want another comp test done by a different tech and i would want to watch it happen.. Get the printout bring it back here.

 

138rpm is impossibly too low. 238rpm sounds more right, especially with the other rotor at 241. The two RPMs should always be close, and the lowest I've ever seen is ~180rpm on an engine that was nearly impossible to start. 138rpm you would never get it started at all.

 

something else I noticed after having looked at the compression chart is that the tech had kfg/c..The ones that are supposed to say 6.x measurements in the box that is for KPa measurement. do techs put in the #'s or is it read by the computer??

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The tester usually reports in 1 scale, and techs may do the conversion for any paper sheet. I wouldn't get wound up about it.

 

Oh well that makes sense. I thought the gage sent the measurement to the computer. so when I remembered seeing that the kfg numbers were in the KPa measurement I was questioning if he even did the test. thanks for clearing that up for me. lol

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Nope, it typically displays the information on the tester itself, and the tech has to transfer it:



There may be versions of the tester that connect or display in alternate scale, though I don't know any details regarding that possibility.

 

Ahhh. Many thanks. Unfortunately I will not be owning an 8. Sad day.

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