check engine light and odd noises

well, I have a 93 chevy and no the engine light wll not come on without the cat, I have no cat never have. Also on a 91 you have to get a scan key(Flat metal test key) and plug it in to the obd 1 plug under the dash. turn your ignition key on and off 3 times ( on off on off on off) the engine light should flash 3 times then there will be a 10 second pause. it will flash the code. you have to count how many times it flashes. once you find out how many times it flashes, you look in the obd1 test book and it will give you a few options, start eliminating things that don't apply to the prob your trying to fix. I presonally thnik it's the egr valve also.

where is the egr valve located on it?

and when i pulled off the spark plugs i examined them. one on the passanger side nearest the firewall smelled like gas. all the others were fine.

so i scanned it finally... it came back with a 43. code book says its is "electronic spark timing(est) circuit-low voltage detected
OR
electronic spark control(esc)- circuit problems"


what the hell is the est or esc? i have no idea how to even do anything with any of this.

possible bad coil, distibutor, plug wire... i would recommend figuring out the preoblem then fix it rather than keep tossing parts at it and trying new things. get a mechanic to diagnose it and pay the diag fee, then fix it yourself.

obd I and II stores every code that is ever thrown until it is reset. So hooking a code reader up will show all the occurances of that code being set.

Sounds like you have a spark plug wire off/coil down/broken plug (something with a cylinder being down) to me. Check for intake boot leaks too, unmetered air getting in will wreak havoc.