97 Nissan Sentra fails emission test, pls help

The car failed to start a month ago. And it was started again by spraying some starting fluid. However, it failed the emission inspection. Reason: Oxygen sensor not ready, EGR not ready, Catalyst not ready. The ECM does not have any error code. When I check the ignition timing with OBDII scan tool, it reads 63 BDTC from ECU when idle. Using timing light ignition timing is unstable during idle. However, it become 0-9 BTDC when rev engin to over 1000 rpm. The specified ignition timing should be 8 BTDC. I checked the engine coolant temp sensor, throttle position sensor, camshaft position sensor, changed the oxygen sensor. Nothing corrected. I then checked the crankshaft position sensor. It turns out that the crankshaft position sensor does not receive any voltage (Should be 5 volt according to the Haynes repair manual). So, I assumed the ECM has a problem. But the problem still exists after I replace the ECM. Any suggesionts? thanks