05 5.3L Tahoe Misfire/Running Rough Issue; Stumped

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Kaeden

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Hey guys, new to the forum and desperately looking for some help.

I started my tahoe as usual today and noticed that it was missing pretty severely as I started rolling. So I pulled out my code reader, and the first thing that came up was a Random/Multiple Misfire Detected code. So my first instinct was to replace spark plugs and wires because the tahoe has 172,000 miles on it and haven't been replaced since I've owned it. Not sure how long the old set had been in there. That didn't fix the issue.

So stumped, I did a little more research as after changing plugs and wires, the code changed from a Random/Multiple to a Cylinder 6 Misfire, O2 Sensor B2S1, and Sensor Reference code. So thinking that the upstream O2 sensor could have something to do with it, I went ahead and replaced both upstream O2 sensors.

Since replacing them, it runs much better. It still starts rough, and seems to stutter occasionally at low RPM but seems to be fine under load or at RPM above 1500. At this point I'm completely stumped. Here are the codes it's still throwing:

P0101 - Mass Air Flow Circuit Range/Performance (MAF is only a few weeks old)
P0161 - O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 2
P0641 - Sensor Reference Voltage A Circuit Open

It's also worth mentioning that I have the codes P0327 and P0332 hanging around, which relate to knock sensors. I plan on replacing them soon, but from everything I've been told and read, these shouldn't be affecting my performance. They've thrown a light since I got the vehicle and have never affected performance.

At this point I'm completely stumped as to what the source is. I've dropped over $200 now in parts to fix something and it isn't even completely fixed yet. So PLEASE provide any help you can. I need it.

Thanks guys!
 

Scottydoggs

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the maf is the biggest issue. it could be a bad new in the box deal. or its aftermarket and the truck dont like it. oem sensors seem to be best always.

the 641 might be related to the maf, most have a fuse, (marked IGN sometimes. it wont say maf fuse) if the fuse blows it tosses a low or no voltage code.

or the maf pig tail wires could be damaged.
 
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Kaeden

Kaeden

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the maf is the biggest issue. it could be a bad new in the box deal. or its aftermarket and the truck dont like it. oem sensors seem to be best always.

the 641 might be related to the maf, most have a fuse, (marked IGN sometimes. it wont say maf fuse) if the fuse blows it tosses a low or no voltage code.

or the maf pig tail wires could be damaged.

The MAF has worked perfectly fine up until this point though? And I'm not even sure if it's the MAF that is performing incorrectly or not. I checked all the fuses labeled IGN and they all appear to be okay. Also didn't see any apparent damage to the MAF pigtail wiring.
 

Scottydoggs

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thats a maf code tho. it will directly affect fueling. causing rough idle crappy shifting too.

the rear o2 code is kinda dont matter. wont effect a thing.

you got a k and n filter you just re oiled? that could set the code too. but being its new not sure a cleaning is the fix, unless its full of air filter oil.

https://www.obd-codes.com/p0101
 
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Kaeden

Kaeden

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thats a maf code tho. it will directly affect fueling. causing rough idle crappy shifting too.

the rear o2 code is kinda dont matter. wont effect a thing.

you got a k and n filter you just re oiled? that could set the code too. but being its new not sure a cleaning is the fix, unless its full of air filter oil.

https://www.obd-codes.com/p0101

I know it’s a MAF code but what’s up with the Sensor Reference Voltage code? Or do you think that’s related to a faulty MAF sensor itself? And no, no K&N Filter. I mean I can always pull the MAF off tomorrow and return it and see if a new one fixes it. I just finished driving it home and it definitely shifts like crap. Shortly after shifts into 2nd and 3rd RPMs drop, and then I can give it some gas and they shoot up and kinda flutter around a little and then level out.

Thanks for the help so far.
 

Doubeleive

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I was having a very similar problem with a 04 little while back and after doing the plugs, coils, wires, intake gasket and knock sensors, it was still rough and shifting weird, right about then the maf threw a code twice, replaced it and everything smoothed out right back to normal
 

Maximus09

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i recently replaced plugs wire and coils on my 2005 5.3 with 100k. truck was having misfires rough idle. after i put new plugs coils and wires truck runs smooth as butter
 
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Kaeden

Kaeden

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Update:

Went to start it to head to work this morning and the thing won’t even start.
 

Scottydoggs

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un plug the maf sensor, then see if it will start up. if it runs the maf is bad.
 

rbogdon

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Had a 96 had similar issues. Especially a specific cylinder misfire... ended up being the fuel pressure regulator leaking directly to a port in cylinder 5... I believe your 05 is a different layout though. All
External. Make sure plug wires are tight and clean the MAF. Good luck.


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