Hi wanglee65,
DTC Code E52 - this diagnostic test monitors the PCM/ECM long term memory for any loss of data. If the battery power or ground are disconnected the code will set (as you see). Code E52 indicates that the "long term" memory in the PCM/ECM has been reset. This will be the case whenever power is removed from the PCM/ECM (i.e., disconnecting battery cables, disconnecting PCM/ECM connector, etc.). This code should be "cleared" from memory after restoring the PCM/ECM's power supply.
To resolve this, the first thing you may want to do is something called a re-learn procedure as when you disconnect the battery, you end up wiping out the vehicles memory of how it is suppose to idle (which is why you are running rich and thus failing the smog check test). So what we need to do to resolve this is perform a re-learn.The second thing I suggest doing is you will need to do a throttle body cleaning procedure.
About the re-learn procedure:
Quoting from a Cadillac bulletin dated Oct. 1990.
"IDLE LEARN IS USED ON 1990-91 DEVILLES, FLEETWOODS ELDO'S SEVILLES AND ALLANTES DURING COAST DOWN TO COMPENSATE FOR LOSS OF AIR FLOW DUE TO THROTTLE BODY DEPOSIT BUILD UP. IF THE BATTERY IS DISCONNECTED FOR A SERVICE PROCEDURE. OR FOR ANY OTHER REASON, THE LEARNED VALUE FOR THE IDLE THROTTLE ANGLE IS LOST. THE RESET PROCEDURE ALLOWS THE IDLE LEARN ROUTINE TO SEEK AND RETAIN THE PROPER THROTTLE ANGLE FOR EACH PARTICULAR THROTTLE BODY CONDITION. THIS DECREASES THE CHANCE OF STALLING DURING COAST DOWN. BEFORE PERFORMING THIS RESET, THE ENGINE MUST BE RUNNING A MINIMUM OF 18 MINUTES ON 1990 CARS AND 13 MINUTES ON 91 CARS. PLACE THE CARS TRANSMISSION IN DRIVE, BRAKES APPLIED. PLACE CLIMATE CONTROLS IN THE OFF POSTION AND ALLOW ENGINE TO REMAIN AT IDLE FOR AT LEAST ONE MINUTE. TURN ON THE CLIMATE CONTROL TO THE AUTO POSITION. LET IDLE ONE MINUTE. PLACE TRANS IN PARK AND TURN OFF IGNITION."
For more info on cleaning your throttle body, please check out: http://www.se-r.net/engine/clean_throttle_body.html
Hope this helps a bit :) Have a great weekend!
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