HP Tuners - Part VIII - Turn Off Catalyst Startup Correction & Over Temp Protection
When a stock Vortec truck is fired up timing advance is altered for 80 seconds to help warm up the cats faster. We don't need the PCM messing with our idle timing during warm up especially since we are not running cats.
Likewise, the rear O2 sensors would aid in the calculation of exhaust temps and provide feedback to the PCM weather or not to richen the fuel to protect the cats from over heating, since we are not running rear O2 sensors, nor cats, there is no reason for the PCM to alter our fueling to protect something that isn't there.
Having said that, please do not turn off Catalyst Protection if you have cats!
1. On your laptop launch the Editor. Open the file we saved in Step 3 of Part VII. (Our last saved file is always our starting point).
2. Make changes in the Editor, this time we will only make two changes both related to the cats. Start by going to Engine \ Fuel \ Temperature Control \ Catalyst Protection and change the pulldown to Disabled. Next go to Engine \ Spark \ Advance \ Catalyst Heating click on the Startup Correction button which will bring up the table and zero it all out, every cell should say "0".
3. Save the changes you made to a new file and call it something like "14 - Turn Off Cat Protection"
4. In your truck, hook up your HP Tuner to the OBDII port and then your USB cable to your laptop, turn the key to the ON position, launch the Editor program, and simply write the new changes to the PCM.
Note:
sometimes you have to write the entire tune file to the PCM, sometimes it is perfectly happy with only writing what's changed, more on this later.
More words with each pic below.