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Discussion Starter · #1 ·
We have owned this '11 Enclave for a year now. A while back I got the code for catalytic efficiency decline and I replaced the catalytic converters and 02 sensors with aftermarket units and the code went away...for awhile. Following that, my wife was driving home recently and was practically overcome by a combination of rich fuel smell and exhaust fumes. This car has a 138,000 miles on it. I decided to change the plugs and coils even though I wasn't sure there was anything wrong with the coils. While I was at it, I observed some oil in the spark plug tubes. Observing oil in the spark plug tubes prompted me to clean that out and replace the valve cover gaskets which came with spark plug tube seals. After the valve cover gasket replacement, the p0420/p0430 codes away but it now also has a p0497 code. ugh. It's been about a week since I put new valve cover and intake gaskets in, and that was not an easy job. It ran like a new car after the gaskets were replaced. But now....I'm smelling rich fuel again and there is a decline in mpg. The problem is returning. So I'm wondering....do I have a bad fuel injector? I replaced the purge valve but the p0497 code remains. The catalytic codes are back.
While in there, changing the intake gasket, I noticed the valves have heavy carbon deposits. Could this be the culprit for the rich fuel smell? Too much carbon on the valves? Or, am I likely to have fuel injector problems? I'm -hoping- the valves just need a thorough cleaning....that would be a lot cheaper than fuel system issues. I'm about to throw in the towel and take it to the dealer but I'm wondering if anyone here has been through this.
 

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Discussion Starter · #2 ·
Anybody have an idea? High pressure fuel pump maybe? I found a youtube video with owner having the exact same problem; rich fuel smile, white exhaust when started. issue went away with replacement of the fuel pump.
 

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2015 Enclave Leather.
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Well if your valves are that dirty with carbon, it could prevent them from closing completely and cause all sorts of issues. I would start with a good cleaning, probably walnut blasting. You need a good Bluetooth scanner so you can read real time vitals, such as cat temps, fuel pressure, etc.
Bluedriver is a good reader, there are others.
 

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2015 Buick Enclave
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You would need to look at your fuel trims and try to isolate if you have may also vacuum leak. Your engine is getting more fuel than necessary. I agree with electbc that you should get a better scanner that can look at live data. Sine the P0420/P0430 are for both banks of the engine, then it's most likely not a bad fuel injector - which would most likely show up on only one side of the engine. Since you have a code for the evap system , you should track that down first, but if it only showed up after you did all your work, then the original cause is still undiagnosed. I would lean towards a bad high pressure fuel pump, pressure sensor or fuel regulator. It wouldn't be easy to track down without some specialized knowledge or equipment.
 

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Discussion Starter · #5 ·
You would need to look at your fuel trims and try to isolate if you have may also vacuum leak. Your engine is getting more fuel than necessary. I agree with electbc that you should get a better scanner that can look at live data. Sine the P0420/P0430 are for both banks of the engine, then it's most likely not a bad fuel injector - which would most likely show up on only one side of the engine. Since you have a code for the evap system , you should track that down first, but if it only showed up after you did all your work, then the original cause is still undiagnosed. I would lean towards a bad high pressure fuel pump, pressure sensor or fuel regulator. It wouldn't be easy to track down without some specialized knowledge or equipment.
Thanks for that. I'm gonna take it in and have these checked. Now it's running codes P0497, p2099, p0430, p0420...runs beautifully though..for now.
 
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