05 5.3L Tahoe Misfire/Running Rough Issue; Stumped

[Kaeden]

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]

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.

 

[Kaeden]

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]

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

 

[Kaeden]

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]

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]

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

 

[Kaeden]

Update:

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

 

[Scottydoggs]

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

 

[rbogdon]

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.


Sent from my iPhone using Tapatalk

 

[Kaeden]

Thanks for all the input guys.

I replaced the MAF under warranty on my lunch break today. Immediately after replacing the MAF it still didn’t want to stay running, however after about 5 minutes of messing with it, it started running somewhat normal again. Something still isn’t quite right because it starts rough and seems to idle a bit odd. Looking at my scan tool and the live data, I’ve discovered the following:

FUELSYS2: CL_FAULT (Why is there a fault?)

P0061: HO2S Heater Resistance Bank 2 Sensor 3 (Where even is a sensor 3? I was only aware of 2)

This problem is getting really frustrating as nothing I’m doing seems to help. Any new feedback?

Thanks again!

 

[swathdiver]

Thanks for all the input guys.

I replaced the MAF under warranty on my lunch break today. Immediately after replacing the MAF it still didn’t want to stay running, however after about 5 minutes of messing with it, it started running somewhat normal again. Something still isn’t quite right because it starts rough and seems to idle a bit odd. Looking at my scan tool and the live data, I’ve discovered the following:

FUELSYS2: CL_FAULT (Why is there a fault?)

P0061: HO2S Heater Resistance Bank 2 Sensor 3 (Where even is a sensor 3? I was only aware of 2)

This problem is getting really frustrating as nothing I’m doing seems to help. Any new feedback?

Thanks again!

I don't even have those codes. Crawl under at your first opportunity and check the wiring of all four O2 sensors. What kind of reader are you using?

As for the MAF, give it some time to relearn but this other problem may prevent that. An advanced scan tool would be nice to have right now.

 

[Kaeden]

I’m just using a generic scan tool I got on amazon forever ago. Would a Bosch CodeConnect be any better?

 

[swathdiver]

I’m just using a generic scan tool I got on amazon forever ago. Would a Bosch CodeConnect be any better?

I don't know, try it. Tech2 would be best.

 

[Kaeden]

I don't know, try it. Tech2 would be best.

Gotcha, I’d love to have one but it’s a bit out of the budget at the moment. I’m gonna try looking at some of the wiring for O2 sensors and such, and well as try the Bosch code reader when I get off tonight and I’ll let you guys know what I find.

 

[swathdiver]

Gotcha, I’d love to have one but it’s a bit out of the budget at the moment. I’m gonna try looking at some of the wiring for O2 sensors and such, and well as try the Bosch code reader when I get off tonight and I’ll let you guys know what I find.

Post up where you live and maybe someone who has one lives nearby. More and more fellas on here are buying them as they generally pay for themselves in short order.

 

[Kaeden]

So I’ve determined that I’m pretty sure the 5V reference wire has a short somewhere. Just not sure where, but it’s throwing an 02 Sensor B2S2 code and the sensor reference code so I checked the sensor wire and it’s voltage was little to none. Now to find the short. Any suggestions? I’ve looked at all the obvious places and don’t see anything.

 

[swathdiver]

So I’ve determined that I’m pretty sure the 5V reference wire has a short somewhere. Just not sure where, but it’s throwing an 02 Sensor B2S2 code and the sensor reference code so I checked the sensor wire and it’s voltage was little to none. Now to find the short. Any suggestions? I’ve looked at all the obvious places and don’t see anything.

Gotta follow it all the way back to where it goes into the cab. Look for chafing and pinching and check the connector thrice.

 

[Scottydoggs]

did you clear the codes after installing the new maf?

rear o2 should not cause the running issues.

 

[Kaeden]

did you clear the codes after installing the new maf?

rear o2 should not cause the running issues.

Yes. The MAF Sensor code has stopped coming up since replacing the MAF. However I still have the O2 B2S1 code showing up as well as the Sensor Reference code. I tested the wire resistance from what I believe is the Sensor Reference wire on the O2 Sensor to the Reference Wire on the PCM connector, and the resistance leads me to believe there is a short somewhere. And yes, I realize that the rear O2 should not affect performance however if it is on the same Sensor Reference circuit as another sensor, another sensor could be having issues as well without necessarily throwing a code, such as the front O2 sensor.