Hello Arnie.
You need to preform a comression test on your engine. A Mazda compression gage would be good, but you can use a standard gage. Excellent will be around 100 psi. I attached a artical below and a link so you can see what a rotary looks like inside. Most common issues with low compression is damaged APEX seals. You would need to replace the engine or find a rebuilder. {not many around}
Good Luck.
Scott.
http://www.rotaryresurrection.com/2ndgen/tech_engine_int_damage.html
The rotary engine used in the RX-7 consists of two rotor chambers each containing a three-sided rotor. Each corner of the rotor has an "apex seal" dividing it into three compression producing regions. As a rotary engine turns, three distinct compression pulses are produced for each revolution of the rotor. These compression pulses can be monitored with a compression gauge placed in the trailing spark plug hole. Remove the Schrader valve from the compression tester. This enables the compression tester to register each pulse as the rotor turns. A compression pulse will cause the needle of the compression gauge to jump up momentarily. The compression pulses must be in a regular pattern and even in intensity. This tests the integrity of each apex seal. A failed apex seal will cause the pulses to become uneven in intensity. If the pulses are in a regular pattern and even in intensity, the engine should be able to produce about 85 psi of compression. To test for available compression, replace the Schrader valve in the compression tester and place it once again in the trailing side spark plug hole. Crank the engine - compression should be about 85 psi.
The Mazda compression testers test engine compression and apex seal integrity in essentially the same manner as the manual test. In other words, the Mazda testers monitor compression pulses and total compression and provide the technician with an easy-to-read result. While not as accurate as the electronic testers, the manual test will give the technician a good idea of the internal condition of the rotary engine.
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