Mazda Repair Questions? Ask Mechanics for Answers ASAP
I would class that as abnormal.
Whether cylinder 4 is abnormally high, or the other 3 are low, the point is they aren't within 10% of each other.
I would say the 4th cylinder must have a different piston.
Did you do the compression test, or was it done for you?
I would ask for another engine if you are buying from a wrecker etc.
How did you go with this?
I hope my advice has been of assistance to you.