i got my 93 nissan sentra eccs and rpm always goes down... i replaced fuel injector,rattle valve,air flow sensor,even fuel pump, tension wire, spark plugs, capacitor which is my stupid mechanic advice. Eventhough i replaced all i mentioned still my engine wont run smooth and my rpm always goes down. My last option is airconditioning system, is it true that this 93 nissan sentra eccs wont run smoothly if no preon?????? i need your advice my bros and sis plssss....

 

first what is the eccs? second did you check for any vacuum leaks cause that can cause a rough idle and power bogging, your a/c compressor will not kick on if it doesnt sense a certain amount of freon, but i believe your car run R12 freon wich is no longer in production, and you would have to get it converted to R134-a. let me know exactly what your asking cause your post is not making that much sense.