Hey everyone,

Just bought an '04 and it has a couple problems that I wanted to get some additional feedback on. It has a rough idle, low power below around 4k and has trouble starting hot. Everything is pointing towards an engine. Ran a compression test the jank way. (Mazda wanted $250 for the test, screw that) My gauge came up with only 60 psi at around 215~225 rpm (according to scanner) on each rotor which seems incredibly low. Would it even really run with that?? Is this result reliable? I almost feel like I did it wrong. Car was fully warmed up. I used two different gauges just to confirm, both the same. I can take the car out and drive it and it won't die and has some good power once you get it going. The idle is rough but not horrible.
Checked the plugs. They all look pretty new. Wires look good. Starter was replaced at some point, I know the original starters for these had issues. Should I even mess with coils? Anything else I should check? Am I doomed??

Thanks.

 

Sounds low...but unless you get a proper compression test you won't know for sure....

Typical rotary though...if they will start they will usually run fine once you are on the gas

 

Buying a rotary without knowing the compression is rarely going to be a positive experience. $250 to prevent you from buying a $1,500 paperweight for a lot more than $1,500... it's a pretty good idea.

Considering you haven't recorded the starter's cranking speed and altitude, those numbers don't mean a thing. Even if you have that information, yes, you still could have done it wrong.

 

Does the rpm reading on the scanner not work for that?

 

Apparently not, since you didn't include it with the numbers.

 

Did you not read my post?

 

Not well enough apparently. My apologies


60psi is off the charts low, assuming you were at sea level.

 

No problem
I'm about 800' above sea level, which, I don't think is gonna make that big of a difference. I'm just really surprised it's even starting up with that low of compression.

 

If you can get it started hot, with just some trouble, then it's probably in the low 6s (kg2cm) or 80s (psi). Just a WAG based on seeing several years of people describing symptoms and later providing compression scores