They are getting so hot because there is so much unburned fuel getting into the exhaust. Does the vehicle run like it is misfiring? Does it run rough?
If not, then if you are willing to try something we can try to pin this down. Run the vehicle practically empty and then put 5 gallons or so of the highest test fuel you can get access too (93 or higher). Then buy a bottle of one of those octane boosters (any brand) and add that to the 5 gallons. Then run the vehicle like normal and see if the converters still glow. If not, then you have what is called detonation.
If it still does it, then we need to monitor the o2 sensor data with a scan tool and see if it is in fact running rich. If it is then we can dig further into causes of a rich condition.
Let me know what you find and we can go from there. Thanks
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Friday, January 31st, 2020 AT 5:49 PM