usmcskeeter
TYF Newbie
- Joined
- Jan 3, 2023
- Posts
- 2
- Reaction score
- 2
The Vehicle:
2012 Yukon Denali XL w/ 6.2 L Flex Fuel
The Problem:
One or both of the catalytic converters on my wife's Yukon Denali has failed to the point that the vehicle would not stay running and would make a terrible squealing sound like the belts were slipping. Codes 0420 & 0430 appeared and back pressure testing proved there was a restriction between the main cats and the 3rd cat. In the test hole, I even found debris. I have no doubt that a piece of the cat is lodged in the Y-pipe. More information in "Background" following my question.
The Question:
I've looked into replacing the entire Cat System and I'm not finding much for the 6.2l version. I can find a bunch for the 5.3L for $500, but when it comes to the 6.2l, I can only find a $1600 option from Magnaflow and a $2500 option from GM. Are there other suppliers out there that sell a replacement cat system? What are the thoughts on what I should do? Vehicle is paid off, but I've just stuck $5K into it between new tires, AFM kit, air suspension, etc. I don't know that I could stomach another $1500 for a vehicle with 200K miles and 10yrs old, but it is still on good condition. I also live in a state without emission testing, so I know I could hollow out the cats, but I don't want to have issues with fuel management, etc. I'm not into performance tuning or exhaust sounds, so I would rather try to keep it stock.
Background:
Around 150K miles I started noticing some oil consumption, lower MPG, and tapping noise coming from the engine - all signs were pointing to the AFM. To try and prevent ripping into the engine, I plugged in an OBD II disabler and it seemed to relieve the symptoms. 50K miles later, one of the few times I drove the Yukon, I noticed it was running rough. I pulled the disabler out to hook up my scan tool and error codes and warning lights started displaying. It was like the disabler was impacting the ability for the ECU to report codes. Between work and the wife getting a new vehicle, the Yukon sat parked for nearly a year.
When I found time recently, I dug into the engine and I found the #1 cylinder to have a stuck valve. I did a Texas Speed AFM Delete and got the ECU flashed to essentially stock configurations (no performance tunes or cams). Yukon drove good after this and so I decided to fix a few things like new tires, air suspension, etc.
After driving the vehicle around for a while, I noticed that the MPGs were still low, there was a rattle coming from a heat shield, low power when towing or accelerating, and then some O2 error codes. I figured I had bad fuel (as most of this started almost immediately after filling up at a tiny gas station), so I ran some BG fuel treatment through the vehicle. Before I could get through an entire tank of treated fuel, I lost engine power going down the highway and when pulling off to the shoulder, the Yukon stalled out and would not stay running. There also was a loud squeal like the belts were slipping. Luckily I was only a mile from home and towed it into the driveway. I pulled all the belts off, but the squeal was still there and the vehicle would not stay running. Then I notice a hissing noise when the engine would stall out and it made me think it was building up too much exhaust pressure. Apparently the AFM had failed for a while and I am suspecting that this poisoned the cats to the point that one or both failed and some of the cat material let loose and caused an obstruction in the Y-pipe as back pressure testing the exhaust system proved this to be the case and what leads me to my question above.
2012 Yukon Denali XL w/ 6.2 L Flex Fuel
The Problem:
One or both of the catalytic converters on my wife's Yukon Denali has failed to the point that the vehicle would not stay running and would make a terrible squealing sound like the belts were slipping. Codes 0420 & 0430 appeared and back pressure testing proved there was a restriction between the main cats and the 3rd cat. In the test hole, I even found debris. I have no doubt that a piece of the cat is lodged in the Y-pipe. More information in "Background" following my question.
The Question:
I've looked into replacing the entire Cat System and I'm not finding much for the 6.2l version. I can find a bunch for the 5.3L for $500, but when it comes to the 6.2l, I can only find a $1600 option from Magnaflow and a $2500 option from GM. Are there other suppliers out there that sell a replacement cat system? What are the thoughts on what I should do? Vehicle is paid off, but I've just stuck $5K into it between new tires, AFM kit, air suspension, etc. I don't know that I could stomach another $1500 for a vehicle with 200K miles and 10yrs old, but it is still on good condition. I also live in a state without emission testing, so I know I could hollow out the cats, but I don't want to have issues with fuel management, etc. I'm not into performance tuning or exhaust sounds, so I would rather try to keep it stock.
Background:
Around 150K miles I started noticing some oil consumption, lower MPG, and tapping noise coming from the engine - all signs were pointing to the AFM. To try and prevent ripping into the engine, I plugged in an OBD II disabler and it seemed to relieve the symptoms. 50K miles later, one of the few times I drove the Yukon, I noticed it was running rough. I pulled the disabler out to hook up my scan tool and error codes and warning lights started displaying. It was like the disabler was impacting the ability for the ECU to report codes. Between work and the wife getting a new vehicle, the Yukon sat parked for nearly a year.
When I found time recently, I dug into the engine and I found the #1 cylinder to have a stuck valve. I did a Texas Speed AFM Delete and got the ECU flashed to essentially stock configurations (no performance tunes or cams). Yukon drove good after this and so I decided to fix a few things like new tires, air suspension, etc.
After driving the vehicle around for a while, I noticed that the MPGs were still low, there was a rattle coming from a heat shield, low power when towing or accelerating, and then some O2 error codes. I figured I had bad fuel (as most of this started almost immediately after filling up at a tiny gas station), so I ran some BG fuel treatment through the vehicle. Before I could get through an entire tank of treated fuel, I lost engine power going down the highway and when pulling off to the shoulder, the Yukon stalled out and would not stay running. There also was a loud squeal like the belts were slipping. Luckily I was only a mile from home and towed it into the driveway. I pulled all the belts off, but the squeal was still there and the vehicle would not stay running. Then I notice a hissing noise when the engine would stall out and it made me think it was building up too much exhaust pressure. Apparently the AFM had failed for a while and I am suspecting that this poisoned the cats to the point that one or both failed and some of the cat material let loose and caused an obstruction in the Y-pipe as back pressure testing the exhaust system proved this to be the case and what leads me to my question above.
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