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Discussion Starter #1
This all started a month or so ago. I got a check engine light for the bank 2 knock sensor. The car has about 61k on it so i changed the sensor. Fuel economy was terrible I went from 16-17 to 12ish. I changed the oil and filter at this time too. Things improved slightly.

However, i still had alot of hesitation when trying to accelerate from a stop. I figured maybe the plugs need to me changed so i replaced them with acdelco plugs. I also changed the coils. Whe i was doing the coils i noticed the theards werw pretty oily on the bank 2 side. I replaced the vavle cover gasket due to a oil leak. The car drove better at rhis point.

The issues became intermittent with fuel economy going to about 14. Scaned the car again and i had a code (no light) for the bank 2 upstream o2 sensor (high voltage) i replaced the sensor and the car has better mpg but the hesitation issue is will there.

Where should i go next? Is there some live freeze frame data i should look at? Im at a loss.
 

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You could check o2 sensor live data with a bidirectional scan tool like the one oreillys has. B1S1 and B2S1 should be changing a lot from low to high B1S2 and B2S2 should change slightly but mostly stay the same.

The hesitation during acceleration seems to be from knock sensor putting the car into limp mode to protect the engine.

I believe GM has an issue with their knock sensors but not sure about the traverse. Is it possible that the sensor wasn’t torqued properly?

If you did then check into your misfire count with a scan tool. Each cylinder will show how many times it has misfired. Might have a bad coil pack. I’ve changed 4 of 6 on mine and wish I would have just bought the 6 pack since it’s much cheaper.
 

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Discussion Starter #3
I changed all 6 of the plugs and coils at the same time. The o2 sensor data is changing and seems to be okay.

In a new development... a few days after i changed the vavle cover gasket i developed a crack in the vavle cover for bank 2 near the filler neck. I figured i over torqued the bolts. So i took it to a friend of mines independent shop. He replaced the cover and gasket with a dealer part. Drove the car for maybe 50-75miles. Vavle cover cracked in the same place. At this point im pretty upset so we checkd the clearances and the chain for that side and everything os as it should be. We replaced the covere again (warranted part). I drove probay another 75miles and the cover cracked for a 3rd time.... the valve cover vent is fuctioning so i dobt think its a pressure issue.
 

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Wow you have gone through quite a few valve covers. I can’t think of anything that would be causing the valve cover to crack like that. Where on the cover is it cracking?

Maybe the timing belt but usually that would leave a groove on the inside.. I can’t image the camshaft lobes could even reach the cover.
 
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