engine compression test... help!
 

Hello everybody
I'm a new user of this website and I would like to ask a question regarding a Mazda3 compression test.

I am really interested on buying a Mazda3 2007, engine 1600cc. This was manufactured in Japan, so it is not an American version.
Few days ago, I went to test its compression for each of the cylinders. The reading for the four cylinders was around 150-152 psi.
Afterwards, we went to test a Toyota Corolla 2007, engine 1600cc. The results were higher, the reading gave us 190 psi for the four cylinders.
The mechanic said that the engine compression of the Mazda3 is really low and that it should be around 200-250 psi. Also, he said that Corolla one is so much better since it is higher than the Mazda.
My questions go here: is the 150 psi result a bad compression? how much does it have to be for this car? corolla's engines are better than the mazda's? I have done some research but I can't really get a really good answer.
The guy who's selling the car says that he provides a good maintainance and that he has not had mechanical problems with the car.

I would really appreciate your help!
Hope you can have some answers for me...

Are you sure your gauge is reading correctly? My only compression-testing experience was on VW Beetles, which were in the 110-125psi range.

After doing a little Googling, your readings appear to be in the right zone. Even more telling, though, is how close your readings are for each cylinder. :)

First off what imma about to say is not in any way false nor rude, its just facts and im here to help.

The 1.6l as well as the 2.0 2.3 etc are all built, designed and assembled in japan, it shares the same platform as the focus but is not built by ford. Compression ratio varies on the type of engine, just because one has more than the other does not mean the other is better unless your comparing the same engine.

Even though the engine says 1.6 does not mean its 1600cc its more like 1560, just like the 2.0 is 1999cc. If all your cylinders are reading close to the same psi then your good, its when its like 100-95-101-65 then you have a problem (in this case number 4 cyl), all readings must be within 25psi of each other.

If you want my opinion i wouldnt buy a new toyota based on the fact they dont perform/last as long as the older ones. As for the mazda 3 its a gamble, either your safe (kinda) or it just starts to fall to pieces once it hits 50k (like my buddies fully loaded 6).

one of the mis-informations here is that a higher compression ratio means higher compression. it doesn't. as tracker said, they all just need to be close to each other. if they are more than 10 psi apart, you are going to have issues.

i don't think that i have ever seen a 4 cylinder motor that put down 200 psi compression numbers. those kinds of compression numbers are only low for a diesel motor. i think that you need to see another mechanic. that's just my $.02.

Thanks bro... I just checked the Corolla engine and it is a gasoline one, so I don't really know what's going on. But as you said, I'd better check with another mechanic. What is the number for a low compression?

Thanks... appreciate your help... So do you think that this number (150 PSI) is good for the engine compression? What should be a low number?

according to my mazda service manual the max allowable difference between cylinders is 30psi. 149.2psi is the minimum for a compression test, standard compression is 213.2psi

Thanks again... does this apply to any mazda model?

as far as the psi difference yes. The spec for the zj engines are 148.4min and 211.9 standard, the LF engines spec are 174.6min and 294.4 standard

i would also go with the mazda.. ive had no problems out of mine and im at 93000 miles