o2 sensors?????

[DeniGirl]

Hello all. I own a 2011 Yukon Denali with the 6.2. After a hell of a time with it, new cat, 3 fuel injectors, new mass air sensor, and new plugs, ALL AC DELCO and a valve spring in cyl 8 and about 2k in parts/labor he is still not up to par. Right before all this my TC service light and stabilitrak lights were randomly coming on and still are. Idle is rough, reads a misfire in cyl 8 still. All I can think of without going to the dealer is that it HAS to be the o2 sensors (should be arriving today). Anyone else have this issue?? I should also mention it has 145k on it. ANY advice is appreciated!!!! I am at the point of hating GM!!! If the o2 sensors do not fix it I am gonna flip.

 

[08grey]

Intake manifold leak?

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[DeniGirl]

We looked it over pretty good, didn't see any leaks, not to say there isn't any....

 

[DeniGirl]

It's specific to cyl 8, which is where the valve spring collapsed that controls the exhaust/gas. Actually did the cat & injectors not knowing it was the spring but they were clogged (was using E-85, was) pulled the cover and found the spring. Got that done and its still running bad. Engine light solid on the dash, randomly TC will show up. Really hoping the o2 sensors will take care of it. Gonna do them both tonight. Got some snow coming.....sucks I have an AWD beautiful truck and got this going on, very frustrating

 

[HiHoeSilver]

@goodinblack, can you please move this to the right section so someone might help?

 

[DeniGirl]

Thanks!!! Not sure what I'm doing :/

 

[swathdiver]

Ma'am you really need to know what the codes are that the CEL is illuminating for. I think your engine is an L94 and not an L9H. If the former it has AFM/DOD which while cruising turns off 4 cylinders for economy, putting the engine in V4 mode. A problem with this system is more likely but we really need to see inside the computer system to better determine what's going on.

Who is diagnosing these problems and replacing the parts?

 

[DeniGirl]

Well we are doing the 02 sensors. I was told by a mechanic it needed a 'tune up' after they did that valve spring. I think they really just didn't know what it was. They used the old 02 on Catalytic converter when they changed it out. And yes it does go into v4 mode.

 

[DeniGirl]

If we unplugged the MAF just for 10 seconds or so and plugged it back in it would idle much better. Really hoping after the 02 sensors it takes care of it. Just wondered if anyone else had had a problem. I miss my 03 Tahoe!!! I just know by reading forums in the past it has really helped and I've learned A lot!!! These new trucks are too difficult!!

 

[swathdiver]

These trucks have 4 O2 sensors, 2 upstream and 2 downstream; 2 different part numbers. The downstream sensors measure the health of the catalytic converters while the upstream sensors monitor the performance of the engine. All that being said, a bad O2 sensor has nothing to do with a misfire on cylinder 8; none whatsoever.

A dealership may prove less expensive in the long run. The actions and diagnosis of your mechanic sets of warning signals and probably you too as you're here looking for advice.