Just a hypothetical question...When deleting your Catalytic converter should you max out all Catalytic overtemp tables? What does the CAT overtemp AFR table do?

 

Just turn off the COT fueling (if a scalar) (and disable the spark retard for catalytist lightoff tables if they exist)

If you cannot turn off COT, just raise the values.

Ryan

 

I have an LT1 and use tunercats. I don't think there is an option to trun off COT fueling so I'll have to raise the values.

I'm still curious as to what the CAT overtemp AFR table does? Is that the AFR that is commanded when a certain temp is detected or is that the lowest afr that can be attained when a certain temp is detected?

 

thanks. i dont believe tuner cats for the lt1 has a disable option but you can raise the overtemp values which in a sense would do the same thing.

if a vehicle does not have a cat how does the pcm monitor the temperature?

 

PCM does not monitor temp, it only makes a
prediction based on motor load, AFR and so on.

Setting the COT EQ value to the same as your
commanded PE is a pretty harmless way to go.

 

That is a good idea too. Last time i was on the dyno the car was stuck at around 12.2 no matter what i was setting the PE at. I didn't know what was going on as i was trying to get it to 11.8 and it wasn't working. While I was working on my regular non WOT tune I came across the CAT Overtemp AFR constant and a light bulb went off in my head. I've tuned the car before and that did not happen to me before on the dyno. Anyway the car likes to be around 11.8 AFR naturally aspirated. Might be because of the overlap (224/236) of the cam. My graphs show the richer the a/f the more power to about 11.8.

 

I have an 08 2500 HD. 6.0 LY6.

In the process of tuning it. ANY Power Enrichment is only done at WOT. The mid range open loop towing, hard driving but not wide open is ALL done by CAT protection.

Let me tell you it runs rich. 11.8-1.

Not really sure what GM is thinking but the stock VE table is stupid lean on top and pig rich on the bottom.

Looks like GM uses Cat protection for more than cat protection.

Stock truck, not even a K+N filter.

You should see the logs....The Arabs love me at the pump!

 

I disabled it. Also set everything to 0, including the tables. If you do a search, there are some older posts with good info. Some guys were able to see some pretty nice dyno gains.