2015 PPV Tahoe Misfires after Heavy Acceleration

[Atlas]

I unfortunately have no reputable private mechanic shops in my area. The last one was closed down for tax fraud. Otherwise I would have.

So in the never ending drama of why I hate dealerships. Got an email this morning that my rear axle seals are leaking and needed to be replaced. Called in to ask about it and it had already been done without my approval. Then just got a call now and they are saying after doing all that work with the lifters that the car is still having issues and they think its the catalytic converter being clogged

```````
went to drive truck and when warmed up truck lost power checked everything and found that there is back pressure from cat converters. gets worse as engine warms up. cats appear to be clogged. was unable to drive prior to replacement of lifters
```````

Am now being quoted $2100 to replace the cat. $1600 for the cat and $500 for the labor. My bill went from an estimate of $2800 to over $6000 including tax. Am i being hustled? Never had a single issue with this car till now.

 

[STORMIN08]

no reason why they can not correctly diagnose the issue...did the engine run excessively HOT and feel like a major struggle to make power ??? that is indicative of a high back pressure issue from clogged cats.

i have had many do this in the past, and you can tell immediately

 

[Miami-Dade]

I unfortunately have no reputable private mechanic shops in my area. The last one was closed down for tax fraud. Otherwise I would have.

Putting in your location might help as maybe a member here can recommend a good independent mechanic for you.

 

[Atlas]

no reason why they can not correctly diagnose the issue...did the engine run excessively HOT and feel like a major struggle to make power ??? that is indicative of a high back pressure issue from clogged cats.

i have had many do this in the past, and you can tell immediately

Before this issue no it did not. They said they believe it was caused due to the car being driven with a misfire.

Putting in your location might help as maybe a member here can recommend a good independent mechanic for you.

From Marlton NJ

 

[Atlas]

More fun updates from dealership woes. Got called Wednesday and was updated that now the other side of passenger lifters would have to be replaced for a fun new total of $6700. Got a call this morning saying that the car would not be ready cause the tahoe still wasnt running correctly. After looking into it more they decided that the camshaft needed to be replaced and due to the fact that they had missed this they would cover the cost of that repair. About 45 mins later they called me back and in the process of tearing down the engine for the 4th time found that the brand new AFM lifter they had installed decided to destroy itself. They need to order a whole new set of lifters and I wont be getting the tahoe back till mid next week.

My only worry now is that something else may have gone wrong and they are covering it up. They did finally offer me a loaner though........ so theres that.

 

[peteytahoe]

Hey all, so I have had my 2015 PPV Tahoe for almost two years now and no real issues until the last couple months. Earlier in the summer it started to struggle in acceleration going from 30+ MPH to 40+ MPH under hard acceleration and threw a P0324 (Knock Control System Error) and had to have both knock sensors replaced, which appears to have resolved that issue. At the same time I had the spark plugs and wires replaced with the GM/ACDelco parts, as a preventative measure. A couple weeks later it threw a P0306 (Cylinder 6 Misfire Detected). I pulled the spark plug and wire, both appeared fine. Put back in and cleared the codes. Went away for awhile and then started up again under heavy acceleration. As long as there is a smooth acceleration all the way up to 80+ MPH there is no issue. About a week ago the issue came back with the P0306 (Cylinder 6 Misfire Detected) plus a new code C0800 (Device power #1 (low current #1) circuit malfunction). I swapped the #4 and #6 spark plug wires and cleared the codes. I am now getting a P0307 (Cylinder 7 Misfire Detected) and am very confused.

Have checked all the cables and connections. Checked the load on the batteries, little old but still giving out the correct readings. Checked if the alternator was providing proper current and was though this was only at idle, didn't have another set of feet to check while revving.

Before I start throwing the part cannon at it, any thoughts on what could be causing these issues? Mode 6 data confirms the misfire counts.


View attachment 351623

My truck was doing the same 2020 6.2 tahoe.. i have pinpointed to im losing compression straight out of the spark plug cylinder 1 0301 code ....

 

[JMH1980]

More fun updates from dealership woes. Got called Wednesday and was updated that now the other side of passenger lifters would have to be replaced for a fun new total of $6700. Got a call this morning saying that the car would not be ready cause the tahoe still wasnt running correctly. After looking into it more they decided that the camshaft needed to be replaced and due to the fact that they had missed this they would cover the cost of that repair. About 45 mins later they called me back and in the process of tearing down the engine for the 4th time found that the brand new AFM lifter they had installed decided to destroy itself. They need to order a whole new set of lifters and I wont be getting the tahoe back till mid next week.

My only worry now is that something else may have gone wrong and they are covering it up. They did finally offer me a loaner though........ so theres that.

Did you ever get this figured out ?

 

[Fless]

Did you ever get this figured out ?

I wouldn't expect a response. The OP hasn't been on here since Nov. 2021. You may want to start a new thread with your info and issues.

 

[JMH1980]

I wouldn't expect a response. The OP hasn't been on here since Nov. 2021. You may want to start a new thread with your info and issues.

Fair enough... I've already had my lifters and camshaft replaced. Once warranty is over, its time for a BTR delete kit.