I have a 92 Camaro RS 305 tbi. I have done many mods with the car running fine after each one. A while back I installed some Hedman Shorties on it and just unplugged the O2 and sat it to the side until I could get a bung welded on later. Of course it runs rich for this period of time because the ecm is getting a lean signal. So the time comes to weld a bung on and I go buy a new O2 and install it(finally some better gas mileage). So its running fine for a while and then I notice something when im at idle. It feels almost like a miss or a slight hesitation. Now, a month later, it is so bad that my car is dieing at lights and im running rich, really rich. Im going through tanks like crazy. BTW, I already rebuilt the TBI unit with new gasket and o ring kit, cleaned the IAC like everyone said to and checked my MAP, TPS and a number of other things. What is going on??!! Any help would be appreciated.

 

It not an uncommon problem. The 5L 'stangs won't idle at all with headers. The exhaust gas is too cold to keep the sensor in it's operating range. I posted an article in the general section about heated O2 sensors. Get a Bosch universal heated O2 sensor and I'll bet it solves your problem. The O2 has to be in the 1200-1400 degree range to properly manage fuel delivery. Headers and low restriction exhaust scavenge so well that the sensor stays out of optimum range. A heated sensor generally solves this problem. Make sure you clear the ECM codes also when done.