2015 PPV Tahoe Misfires after Heavy Acceleration

[Atlas]

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.

 

[STORMIN08]

did you perform an OHM ( Resistance ) test on the plug wires ? could also be a failing coil, but since the issue moved with the wire, i would be checking that first.

 

[Atlas]

Hey just so I make sure im correct the engine ignition order is 1,3,5,7 on the drivers side of the engine and 2,4,6,8 on the passengers correct? Took my lunch break and checked all the cables with a multimeter and all are fine.

Anything else I should be checking? could voltage spikes from the alternator or battery be causing this issue?

 

[Atlas]

Heres a link to some data logs as well. I do see some spikes in the MAF and the Control Module Voltage

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

 

[STORMIN08]

that is cylinder orientation / location, but not firing order.

when this happens, does the Check Engine light illuminate and stay or does it flash...the indicates to types of issues. a steady light is generally a sensor, flashing is real time issue and should be shut down and checked

 

[Atlas]

Flashes and goes away. Like I mentioned before. As long as there is smooth acceleration there is no issue, only after heavy acceleration (flooring it) does it have issues and even then Engine doesnt stumble, no lights dim, no new noises. I also linked some data logs above but it is awaiting moderator approval.

 

[STORMIN08]

mine did this similar thing on a road trip, while raining. i would lean towards a sensor connection...check all coil harness connections, possibly even remove, clean and use dielectric grease.

mine has not done it since i removed and reconnected everything

 

[Atlas]

So unfortunately last night tahoe started to completely miss while driving. Tahoe went straight into limp mode, stabilitrak disabled, abs as well. Multiple codes thrown. P0307, P0300, C0800, U0401. Was lucky it broke down close to my local dealer and dropped it off last night. Called me back today and they are pretty sure it is a lifter failure. They are quoting me $2800 for the work. $1950 for labor and $850 for parts. Of course this is only for the drivers side. They will check the passenger lifters and camshaft for damage as well.

Price seems a little high, but only by a little, otherwise about right from what Ive seen. Question is should I be having them replace the other lifters now? Anything else while its getting done?

 

[Joeltz]

So unfortunately last night tahoe started to completely miss while driving. Tahoe went straight into limp mode, stabilitrak disabled, abs as well. Multiple codes thrown. P0307, P0300, C0800, U0401. Was lucky it broke down close to my local dealer and dropped it off last night. Called me back today and they are pretty sure it is a lifter failure. They are quoting me $2800 for the work. $1950 for labor and $850 for parts. Of course this is only for the drivers side. They will check the passenger lifters and camshaft for damage as well.

Price seems a little high, but only by a little, otherwise about right from what Ive seen. Question is should I be having them replace the other lifters now? Anything else while its getting done?

My 2015 did the backfire just as you let off engine code cleared…. Did the POP a few days later.. never cleared limping… lifter stuck…. I said to myself have to get rid of the lifters and all local shops kept saying Swap in a junkyard motor

chevy said about 3000$ to change lifters

i Found a speed shop 150 miles away….. had it towed on a flatbed and waited 3 weeks

360 Customs put in a Texas speed Dod removal Cam kit & LS 7 regular lifters

1000 miles so far saw 24.9 on a highway run at 67 mph is starts and runs like it should

They DYNO tuned it to have computer forget the V8-V4

cost right at $3000
my advice change cam lifters and dyno tune it

The dealer would Not Do this I asked !

 

[STORMIN08]

i recommend doing the entire top end if going in there...last dealer trip i recall hearing of was roughly 4K for the whole deal.

i would be doing a DOD delete from a performance shop, and adding a nice bottom end torquey cam.

 

[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.