I have an rtec 2.1 in my 87TII that has never been tuned. I just have minor mods such as BNR stage 2 turbo and an an ARC top mount intercooler and 720cc secondaries. I was wondering about fuel corrections. My understanding is that the stock CPU makes fuel corrections on it's own. So does the reprogrammed Rtec also make fuel corrections on it's own?

 

The point of the Rtek is so you can make your own fuel corrections. The ECU will make some corrections for part throttle driving based on the O2 sensor, but the Rtek doesn't do anything in that regard that the stock ECU doesn't.

 

to further elaborate, you must measure your fueling with a wideband 02s sensor, and use a laptop or palm to access to software to correct the measured fuel curve.

 

So the stock ECU makes minor fuel corrections based on the narrow band O2 sensor but once the engine is modified beyond a certain point fuel and timing corrections have to be made.