So heres the deal: about a week ago, i had a problem with my car stuttering when im at or below the 2000 rpm range while accellerating, so I had to just shift at higher rpms and it was fine. I finally got an engine code, it was just a 43, so I changed the plugs and wires(it was about time for that anyway). It ran great after that but I also noticed that i had a tube seal leak so i changed the seals like 2 days ago. Then, on my hour drive home from that, my car starts idling really crazy, down to almost 0 and then picking up right before it stalls, up and down. Sometime around now, my check engine light (which i forgot to reset) turned itself off, which i thought was unusual since this car usually has to be reset. I was only like a block from home, and it seemed like as long as i was in a high enough rpm range it was alright, just couldnt idle properly. So I drove it home, shut the car off, looked under the hood, nothing unusual looking. So i just made sure all the spark plug wires were seated properly, the ground wire attached to the valve cover was nice and tight, and checked that the pcm was plugged in nice and tight. Nothing really seemed loose, but when i turned the car back on, it ran just fine. I drove for 2 days with no problems, and today on my way to school, my battery light comes on. When i stopped I checked the engine codes, and i got 42 43 47 (and of course the usual 12 and 55). The wierd thing is that my engine light isnt on, but if i check the codes, it will still flash, so I know its not the bulb. Could this be an alternator problem? or is it possible that my computer is messed up?

 

if your battery light is on, its possible that the alternator isnt charging it properly, and making other things go haywire.
id try to chage out the alternator, reset the computer, then turn the car back on and see what it does.

 

the alternator was only pushing 11.9 volts... its so cold out. Im so bummed i have to do this in the snow.

 

put a new alternator in today. Does the same thing. Headlights are dim as hell. Other than that it runs fine though. Im guessing its the alternator voltage regulator, which i read is located inside the pcm, which blows. Im going to go get the pcm tested I guess to see if thats the problem. How much do those things cost? Can I get one from a junkyard, and if so what PCMs will fit my 99 mtx sohc neon?