I have a 93z with a procharger and DFI system and I recently used some 116 race fuel. After the use my car has been leaning out. The store I got it from had two grades. One being the normal and the other not having much oxygen in the blend which he said is used for high boost turbo application. I told him I just needed the regular 116 with my setup and he agreed b/c the one with less oxygen would screw up my tune from his explanation. After using the fuel I noticed a change in the sound of the car and the performance was lacking. Now when I start the car and let it idle for about 5-10 min the headers turn red. I wondering if he gave me the wrong fuel and what effects it can have on my tune. I change the o2 sensor but the problem still exist. What could be some other causes? I have run race fuel b4 but never that high of a grade. Please help!!!

 

Do you have cats? Leaded fuel will ruin them, along with the O2 sensors.

Does your DFI system operate in closed loop?

 

no cats on the car

 

OK.... let's try this again.

Does your DFI system operate in closed loop? Because if its not running in closed loop, the O2 sensor is not used to control the A/F ratio. If its running in closed loop, the O2 sensor helps the DFI maintain the A/F ratio, and if the sensor is contaminated, it will screw things up.

If you don't want to provide more info, you're not likely to get help.