Engine misfire code and runs like crap help! - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Ponchonutty · 10-11-2020, 06:49 PM

2012 Camaro SS with the L99. Has been tuned along with DOD turned off for a few years as well as full stainless exhaust with shorty headers and down to 2 hiflow cats. Starting this summer I could notice a slight miss when cold but otherwise ran great. I then changed all plugs and wires with stock plugs and Taylor wires. It has sat most of the summer due to working so much but it’s never missed a beat. Well drove it an hour to and it started sounding off. Couldn’t figure out what’s going on. Under hard acceleration it will flash the check engine light along with the stabilitrack and associated lights. If putting around it stays off. Pulled codes of 420,430 and misfire on cyl 3. Pulled the plug and it is all carboned up even though it only has 500 miles on it. The rest look fine. What’s everyone’s thoughts? Dropped valve? Bad coil? Bad cat converter???

Greenhornet2 · 10-12-2020, 07:30 AM

if it's a valve you would likely hear a noise and it would miss at idle. Do a compression check. swap the coil to the other bank and the plug to a different cylinder. Test drive see if you can get the code to come back and see if it moved to a different cylinder, if it did replace whatever you moved to that cylinder. If it stays on #3 then you look at the injector. If compression is down, then you have more problems. Post your findings.
The converter could be toast if it's be running with a misfire dumping raw fuel into it. If the misfire is on more than one cylinders on a single bank I'd be looking into a possible clogged cat as well.

krusher · 10-16-2020, 01:11 PM

When I had that I had a bad injector. One had a bad injector code and one did not. The one with a bad code had a wire melted in half to one of my injectors.

The other had similar codes, but not for the injector, moved the injector and it followed to the next cylinder so I changed it.

Most issues I have with that code though is I thought I had the plug wire on and it ended up being not quite on the plug.

StingrayblueSS · 10-16-2020, 04:12 PM

You probably already have but I would check the plug wires. When I had Taylor wires they wouldn't stay on the plug and I ended up swapping them for a different brand. They had the 45 degree boot.

Ponchonutty · 10-19-2020, 01:55 AM

Well today I swapped coils between #1 and #3. I also swapped injectors on the same cylinders too but made do difference. Pulled valve cover off and rotated engine by hand. Valves open and close as they should. My CEL only comes on if I’m on it or if it’s up around 3k rpm. At idle nothing is shown.

krusher · 10-20-2020, 08:52 AM

What about spark plug? I know its new, but I have had a bad plug right out the box or cracked and never seen it.

Ponchonutty · 10-31-2020, 07:06 PM

Ended up finding the issue. Stupid hi-flow cat failed and plugged up the exhaust. I cut open the cats, removed the guts then Weser them back up. Since the day I installed them I swore I could hear a rattle over certain bumps. I don’t have that anymore. The “good” cat you could feel it move inside the pipe when I removed it.

InFiD3ViL · 10-31-2020, 10:08 PM

Wow, nice find man. That actually looks melted. I've heard about melted cats plenty but never actually seen one. I guess it gets so hot that it melts and then plugs itself? That is insane.

The important question here is...How does she sound now?!

krusher · 11-02-2020, 09:20 AM

That's why I don't have them in my car. We don't have inspections in IA thank god. I got cats used and they came looking like that so it left me a bad taste.

I actually had issues the last month and looked like a vacuum leak and here my bank 1 sensor one failed but had no code. Was really curious if it was your issue as well. Glad you found it.

Ponchonutty · 11-03-2020, 05:59 PM

Here’s a quick video on a cold start up. Definitely louder but wasn’t too bad cruising down the road

https://youtu.be/1IMYYMU3MY4

Machh5 · 11-19-2020, 04:41 PM

There is most likely something else going on that the cat melted on that side and not the other.

10-12-2020, 07:30 AM	#2
Greenhornet2 Drives: 2011 Camaro 2SS LS3 Whipple Join Date: May 2019 Location: Connecticut Posts: 1,925	if it's a valve you would likely hear a noise and it would miss at idle. Do a compression check. swap the coil to the other bank and the plug to a different cylinder. Test drive see if you can get the code to come back and see if it moved to a different cylinder, if it did replace whatever you moved to that cylinder. If it stays on #3 then you look at the injector. If compression is down, then you have more problems. Post your findings. The converter could be toast if it's be running with a misfire dumping raw fuel into it. If the misfire is on more than one cylinders on a single bank I'd be looking into a possible clogged cat as well. __________________ Whipple 2.9 CAI ID1050x injectors ZL1 Pump JRE FPCM JMS Voltage booster JRE Rough Idle blower cam BTR .660 springs CHE trunnion kit 1 7/8 Speed Engineering Borla Atak JRE scoop 1.5" lowering springs BMR trailing arms and toe links Cradle inserts 704WHP 603WTQ 93 octane

10-16-2020, 04:12 PM	#4
StingrayblueSS Drives: 2013 Camaro SS Join Date: Feb 2017 Location: Indiana Posts: 901	You probably already have but I would check the plug wires. When I had Taylor wires they wouldn't stay on the plug and I ended up swapping them for a different brand. They had the 45 degree boot. __________________ 2013 Camaro SS Kooks Headers Vararam DRX 1le Differential 3.91 Bo White throttle body Magnaflow Competition Exhaust 12.391 112 MPH 10/05/19

10-19-2020, 01:55 AM	#5
Ponchonutty Drives: 2012 SS L99 Converible Join Date: Mar 2016 Location: New Washington, Ohio Posts: 606	Well today I swapped coils between #1 and #3. I also swapped injectors on the same cylinders too but made do difference. Pulled valve cover off and rotated engine by hand. Valves open and close as they should. My CEL only comes on if I’m on it or if it’s up around 3k rpm. At idle nothing is shown. __________________ 2012 L99 Convertible SS Tooley Racing Stage 2 DOD delete, 3,200 stall converter, Shorty headers and custom stainless exhaust, CAI, and tune as mods

10-31-2020, 07:06 PM	#7
Ponchonutty Drives: 2012 SS L99 Converible Join Date: Mar 2016 Location: New Washington, Ohio Posts: 606	Ended up finding the issue. Stupid hi-flow cat failed and plugged up the exhaust. I cut open the cats, removed the guts then Weser them back up. Since the day I installed them I swore I could hear a rattle over certain bumps. I don’t have that anymore. The “good” cat you could feel it move inside the pipe when I removed it. Attached Images __________________ 2012 L99 Convertible SS Tooley Racing Stage 2 DOD delete, 3,200 stall converter, Shorty headers and custom stainless exhaust, CAI, and tune as mods

10-31-2020, 10:08 PM	#8
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,584	Wow, nice find man. That actually looks melted. I've heard about melted cats plenty but never actually seen one. I guess it gets so hot that it melts and then plugs itself? That is insane. The important question here is...How does she sound now?! __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

10-11-2020, 06:49 PM	#1
Ponchonutty Drives: 2012 SS L99 Converible Join Date: Mar 2016 Location: New Washington, Ohio Posts: 606	Engine misfire code and runs like crap help! 2012 Camaro SS with the L99. Has been tuned along with DOD turned off for a few years as well as full stainless exhaust with shorty headers and down to 2 hiflow cats. Starting this summer I could notice a slight miss when cold but otherwise ran great. I then changed all plugs and wires with stock plugs and Taylor wires. It has sat most of the summer due to working so much but it’s never missed a beat. Well drove it an hour to and it started sounding off. Couldn’t figure out what’s going on. Under hard acceleration it will flash the check engine light along with the stabilitrack and associated lights. If putting around it stays off. Pulled codes of 420,430 and misfire on cyl 3. Pulled the plug and it is all carboned up even though it only has 500 miles on it. The rest look fine. What’s everyone’s thoughts? Dropped valve? Bad coil? Bad cat converter??? __________________ 2012 L99 Convertible SS Tooley Racing Stage 2 DOD delete, 3,200 stall converter, Shorty headers and custom stainless exhaust, CAI, and tune as mods

10-16-2020, 01:11 PM	#3
krusher Drives: 2010 Camaro SS/RS CGM Join Date: Dec 2011 Location: Oskaloosa, IA Posts: 627	When I had that I had a bad injector. One had a bad injector code and one did not. The one with a bad code had a wire melted in half to one of my injectors. The other had similar codes, but not for the injector, moved the injector and it followed to the next cylinder so I changed it. Most issues I have with that code though is I thought I had the plug wire on and it ended up being not quite on the plug.

10-20-2020, 08:52 AM	#6
krusher Drives: 2010 Camaro SS/RS CGM Join Date: Dec 2011 Location: Oskaloosa, IA Posts: 627	What about spark plug? I know its new, but I have had a bad plug right out the box or cracked and never seen it.

11-02-2020, 09:20 AM	#9
krusher Drives: 2010 Camaro SS/RS CGM Join Date: Dec 2011 Location: Oskaloosa, IA Posts: 627	That's why I don't have them in my car. We don't have inspections in IA thank god. I got cats used and they came looking like that so it left me a bad taste. I actually had issues the last month and looked like a vacuum leak and here my bank 1 sensor one failed but had no code. Was really curious if it was your issue as well. Glad you found it.

11-03-2020, 05:59 PM	#10
Ponchonutty Drives: 2012 SS L99 Converible Join Date: Mar 2016 Location: New Washington, Ohio Posts: 606	Here’s a quick video on a cold start up. Definitely louder but wasn’t too bad cruising down the road https://youtu.be/1IMYYMU3MY4 __________________ 2012 L99 Convertible SS Tooley Racing Stage 2 DOD delete, 3,200 stall converter, Shorty headers and custom stainless exhaust, CAI, and tune as mods Last edited by Ponchonutty; 11-03-2020 at 06:01 PM. Reason: Added to it

11-19-2020, 04:41 PM	#11
Machh5 Account Suspended Drives: Camaro Join Date: Jun 2020 Location: US Posts: 120	There is most likely something else going on that the cat melted on that side and not the other.