i got this 93 hatch a week or so ago. driving home i noticed it would hesitate and pop alittle around 2k rpms but when you got to 3k and up it ran fine. It idled perfect. it had a CEL for code 3-map sensor and code 41 primary o2 sensor heater malfunction. I swapped out the map sensor for one that worked fine on a friends car. it got rid of the map sensor code but still hesitated and drove the same as before but idled perfect, i drove it 2 miles and when i got back i let it sit for about 20 minutes then went out to leave and started it up and it was idleing real low and rough and smelled like gas bad, checked the ecu and still only getting code 41. any idea whats wrong here?

 

primary 02 malfunction, its why your idle is low, same problem with my 97 ex change and now fix

 

i dont get why it would only start doing that now tho when the code 41 was on since i got it and it idled perfect

 

did you dissconnect the battery, reset the ECU or did the battery die about the time this started?

 

disconnected it to reset. battery didnt die and it starts up fine

 

well, thats it then. Before the reset the ECU was "used to" the bad O2 and already new the quirks of the engine. so it ran fine.... When it was reset, it had to relearn your engine. I would bet its running fairly rich now... replace the O2 sensor and i bet it will clear up.

 

its running rich but sounds like a misfire. I dont get why its o2 sensor heater? does that mean the o2 sensor is definitely bad?