[Azure_King]

So, new to the forum, nice to meet everyone!

I have a 2016 Camaro SS with 57k on the clock; It has a misfire on cylinders 5&8 between 3-4k Rpm.

So far I have replaced all fuel injectors, the fuel pumps and the ignition system(plugs, wires, and coils) this has been an issue since i bought the car a year ago and I’ve taken it to two chevy dealers and they can’t seem to figure out whats wrong.

Recently I reset the torque on all the rocker arms just incase something was too tight and to make sure i didn't have a weak or collapsed lifter...

Any Ideas? Thanks in advance!

P.s. the car is stock aside from long tubes, and a tune.

[ssmofo]

I would suspect the tune if you have changed all that, does it bring on the CEL?

[Wilka_SS]

Check for a broken valvespring or carbon collected on either of the intake and exhaust valves preventing the valve from seating and sealing.

[Azure_King]

@SSMoFo- this has been an ongoing issue since the car was bone stock; CEL flashes but doesn’t stay on.

@Wilka_SS- None of my valve springs appear to be cracked or broken... I’ll have to check throughly for carbon buildup on valves.

[sal11585]

I am no expert , but maybe its something electrical . Maybe the wiring to the coils or something. Especially since its always done it and looking at what you replaced already, I cant think of anything else it could be.

[Cechk01]

it should still be under powertrain warranty, tell the dealer to fix it

[Azure_King]

Originally Posted by sal11585

I am no expert , but maybe its something electrical . Maybe the wiring to the coils or something. Especially since its always done it and looking at what you replaced already, I cant think of anything else it could be.

Everything looks fine visually... I’ll put a multi meter on the harness this weekend just in case...

[Azure_King]

Originally Posted by Cechk01

it should still be under powertrain warranty, tell the dealer to fix it

My warranty expired a couple months ago.

However, I have a 3rd party extended warranty that covers what chevy would in their powertrain warranty(all internally lubricated parts, not including injectors).

[Gunkk]

Originally Posted by Azure_King

My warranty expired a couple months ago.

However, I have a 3rd party extended warranty that covers what chevy would in their powertrain warranty(all internally lubricated parts, not including injectors).

Waitasecond....How is a 5/60 warranty expired already at max 4 years and 57k miles?

Edit: nevermind, I see you have a tune.

[Azure_King]

Originally Posted by Gunkk

Waitasecond....How is a 5/60 warranty expired already at max 4 years and 57k miles?

Edit: nevermind, I see you have a tune.

Good eye, but my dealer didn’t care about the tune...

Edit: Checked my e-mail again; the notice was to let me know my warranty was expiring soon

[Azure_King]

Update: As of right now there is no more misfire, we’ll see what happens when I take her back to the dyno...

Things I did: checked all wiring from the ECM to each coil(no issues found), checked all ECM fuses and relays(no issues found), Replaced all pushrods and re-gapped spark plugs from .040 to .035.

Thanks for the input guys!

[Azure_King]

Update: Maybe I can save someone a headache later down the line

So, the misfire came back a few weeks after the aforementioned parts were replaced

So, I took my time and diagnosed a little better....
Misfire only happened at 3k or higher steady state throttle.

I already ruled out the ignition system, fuel system, and the possibility of damaged lifters push rods and valves.

So... I ended up marking my valve springs with a paint marker and gave her a good rev to 4k and lo and behold.... My valves were floating (photos attached)



Hope no one else runs into this issue, but on the bright side the LT1 is a non interference engine in stock trim

Good Luck out there and remember to be thorough when troubleshooting.

[FlukeSS]

Probably a Necro, but had a question:

I've been having a misfire issue on my car, and I am wondering if I might have the same issue.

Car only seems to misfire under load over 3000 rpm and always right before or after a shift even at high rpm's.

And it happens on two different tunes, a conservative tune, and my more aggressive tune.

The car ran fine on the aggressive tune up until May 8th or so of this year 2024.

I've swapped back and forth between the conservative tune and the aggressive tune. The misfires are worse on the aggressive tune, but still present on the conservative tune as well.

I hear a sputtering in the exhaust. While on the aggressive tune I get a loss of power along with the sputtering, on the conservative tune, I don't really get a loss of power but can still hear the sputter on the conservative tune.

Original Rebuild parts list:



I've already had the car checked for the below:

1. Replaced spark plugs twice original sparkplugs were NGK-LTR7 after the engine rebuild with NGK-LTR5 I was told to switch to LTR6 instead

2. Replaced both upstream left/right O2 sensors

3. Replaced Plugwires

4. Car in shop - No Leaks, 160-170 psi compression test, had coils checked, and injectors (although for injectors they only checked for wet spark plugs) Shop said they couldn't find anything mechanical wrong with the car, but no idea if they bothered to check for Valve float.

5. Don't believe it is a fuel pressure issue according to logs fuel pressure seems to be where it should be.

I suspect valve float because I assume the valves are original stock with upgraded dual valve springs from BTR.

Would this be a fair assessment in my case?

Would this be something to check?

Also have a log or two of mild pulls at about 3000-4000 rpms which is when I start to hear the sputter after the shift.

[SomeGeoffGuy]

Fluke - did you do a crank sensor re-learn? Whenever I hear someone having higher RPM breakups that is the first thing I think of. That was always a thing on the LS engines. Not sure if the LT engines are the same.

-Geoff