Engine misfire?

[jasonsk287]

Hello all,

I wanted to post this to see what feedback you could provide. I have a 2012 Chevrolet Camaro 1LT with the LFX V6. No mods or altercations of any kind. The car has about 45,500 miles, so of course it’s out of warranty. Back in January, in relatively cold weather, I felt a shaking in the engine area and the check engine light came on. After a day, the light went out, but I brought the car to my dealer anyway and they told me the car showed the code P0300, and over 300 misfires were indicated in one of the cylinders (not sure which one it was). They replaced an ignition coil under warranty and told me to bring it right back if it happened again. Mechanic also told me “It could have been bad gas.” That was at around 34,000 miles. No issues until two days ago, when I was driving to work and noticed a particularly hard downshift and a solid check engine light. I called OnStar and had them run a diagnostic on it. They didn’t tell me the code but they said it showed an “engine misfire” and that I should take it to my dealer within 7 days. That was yesterday, and I have an appointment tomorrow to take the car in. This morning I check the car out before work, and no more check engine light and the car appears to be driving normal.

So now I’m going into this tomorrow morning knowing what the issue is (or rather, was), but not knowing what caused it. I’m worried that the dealer may not be able to replicate an issue. Also- a general question- if there is an issue with engine misfiring that requires work, is any of that covered under the powertrain warranty? I read the powertrain warranty info and I noticed that it says “excludes wiring and connections” so I’m not sure if they’ll find a reason for it not to be covered.

Thanks in advance for any advice you can give me. My car is amazing otherwise, this is the only issue it’s ever had!

Jason

Edit: I did a search but everything I found didn't seem to partain to my engine or people had mods done, so I wasn't sure if anyone else was in my situation. Thank you!

[Eddiefuzz]

It's an ignition coil. Take it to an auto parts store, they can tell you the code, each cylinder has its own code. Ignition coils are about $25 on EBAY, they're about $45 at an auto parts store, you can switch it out yourself. I've done five of the six in my car and I keep an extra in my tool box. PS. A Hyper-Tech tuner is a great tool for reading and clearing codes. Sometimes you can clear a code and see if it comes back, before you take it to get fixed.

[Chevrolet Customer Svc]

Originally Posted by jasonsk287

Hello all,

I wanted to post this to see what feedback you could provide. I have a 2012 Chevrolet Camaro 1LT with the LFX V6. No mods or altercations of any kind. The car has about 45,500 miles, so of course it’s out of warranty. Back in January, in relatively cold weather, I felt a shaking in the engine area and the check engine light came on. After a day, the light went out, but I brought the car to my dealer anyway and they told me the car showed the code P0300, and over 300 misfires were indicated in one of the cylinders (not sure which one it was). They replaced an ignition coil under warranty and told me to bring it right back if it happened again. Mechanic also told me “It could have been bad gas.” That was at around 34,000 miles. No issues until two days ago, when I was driving to work and noticed a particularly hard downshift and a solid check engine light. I called OnStar and had them run a diagnostic on it. They didn’t tell me the code but they said it showed an “engine misfire” and that I should take it to my dealer within 7 days. That was yesterday, and I have an appointment tomorrow to take the car in. This morning I check the car out before work, and no more check engine light and the car appears to be driving normal.

So now I’m going into this tomorrow morning knowing what the issue is (or rather, was), but not knowing what caused it. I’m worried that the dealer may not be able to replicate an issue. Also- a general question- if there is an issue with engine misfiring that requires work, is any of that covered under the powertrain warranty? I read the powertrain warranty info and I noticed that it says “excludes wiring and connections” so I’m not sure if they’ll find a reason for it not to be covered.

Thanks in advance for any advice you can give me. My car is amazing otherwise, this is the only issue it’s ever had!

Jason

Edit: I did a search but everything I found didn't seem to partain to my engine or people had mods done, so I wasn't sure if anyone else was in my situation. Thank you!

Jason,

My apologies regarding your Camaro's engine misfire concerns. Although I understand your displeasure, it's great that you've proactively reached out to your dealer for an official diagnosis. Keep us in the loop and updated on your service visit. If necessary, I can contact the dealer's Customer Experience Managers if you have additional questions. We'll look forward to your updates .

William R.
Chevrolet Customer Care

[Majic]

P0300 is a "random misfire". If you had a recent "history" and it could identify which cylinder was bad it would be 0301..02..03 etc and indicate which one misfired. They can go to the history and determine which cylinder is bad tho. Coil and plug change on bad cylinder.

[EMB135Driver]

Thought we had a 5 yr/60000 mile power train warranty.....Engine is part or the power train right?

[Cam#7]

I have a 2011 2LT with 51,000 miles. When I hit 25,000 miles, I also got a misfire code. It would run rough for a few seconds after a cold start. My dealer put dye in the coolant and had me drive it for a week. They verified later that I had a pin hole in one of the cylinders and they replaced the engine. I was told they had a batch of bad engines with thin cylinder walls.

No problems since.

[CamaroCracka]

"Bad gas" can't cause a misfire on one cylinder unless trash got past the filter and clogged an injector, but as previously stated that is a general misfire code. If its scanned while running, the culprit cylinder will likely show itself. If it's spark it's usually a plug, wire, or coil, but it can be as simple as a loose connector.

I had this happen on my Silverado because my foot broke a plug and my plug wires were old so it was a little tricky to figure out, but if I can figure out multiple simultaneous spark issues with an AutoCal, surely the dealer can figure it out.

[jasonsk287]

Hi all,

Dealership is telling me the car needs a $447 "top engine cleaning"... this doesn't make sense? I told them not to do it. Would really think this should be under the powertrain warranty at 45,000 miles. And of course it couldn't have been done until tomorrow and "they have no loaners"... Thinking I should try another dealer. Oh and $120 charge just to check what the code was... p300 just like I knew it was. Not happy right now. But thanks everyone for the advice. We'll see what happens

[Rock-It Man]

Originally Posted by jasonsk287

Hi all,

Dealership is telling me the car needs a $447 "top engine cleaning"... this doesn't make sense? I told them not to do it. Would really think this should be under the powertrain warranty at 45,000 miles. And of course it couldn't have been done until tomorrow and "they have no loaners"... Thinking I should try another dealer. Oh and $120 charge just to check what the code was... p300 just like I knew it was. Not happy right now. But thanks everyone for the advice. We'll see what happens

Of course you should find another dealer, and get your $120 back.

Just amazing that a dealer would charge you to check a code on a car that's under warranty. Apparently some dealers just don't want their customers' repeat business!

[jasonsk287]

So just to clarify. The tech who looked at my car came out and said there was carbon buildup on the top of the engine, so they recommended a "flush" which is what I mentioned earlier. They also said that they would need to redo an oil change, even though I just had one last week and have 95% oil life left. He said generally in cold starts the carbon buildup makes it more likely for a cylinder to misfire. I asked if doing this would solve the problem, the tech said usually it does at least for 100,000 miles or so. I'm definitely getting another opinion though. As of right now the car is fine and has no lights on. And the $120 diagnostic- I asked what it entails. I said "is that just for plugging it in and seeing what the code is?" and the lady said "oh no, much more than just plugging it in. They do a diagnostic on the whole engine." Uh huh. I trust the mechanics but who really knows if the work is $120 worth.

Sorry for the rant, I really do love my car but $450 is a lot for me to swallow right now, if I knew it was 100% necessary for engine health that would be a different story! but I wanted to get opinions from fellow owners first. Thanks everyone

[qcman]

I would think you could Seafoam it and do it yourself. Search around on this forum for that and how to do it.

Cam

[Eddiefuzz]

Originally Posted by Eddiefuzz

It's an ignition coil. Take it to an auto parts store, they can tell you the code, each cylinder has its own code. Ignition coils are about $25 on EBAY, they're about $45 at an auto parts store, you can switch it out yourself. I've done five of the six in my car and I keep an extra in my tool box. PS. A Hyper-Tech tuner is a great tool for reading and clearing codes. Sometimes you can clear a code and see if it comes back, before you take it to get fixed.

This guy gave you some good advice.

[jasonsk287]

Eddiefuzz, thanks for your advice! I did see your comment earlier and I will look into the ignition coils at my local shops. I asked the tech about the ignition coils and he seemed to push the engine clean thing instead, but I'm not sure if he did that because they want to make the $500... Also i really like the idea of the code reader, i didn't know that was even possible! Thank you again for your input!

[Nutbutt]

If you go to the V6 section and search for p300 you will find that the dealership is probably correct. These v6 really need a catchcan to prevent blow by that these engines experience. Instead of having the dealership do the top end cleaning do it yourself for $20. Go get some seafoam and follow the instructions. Also there is a diy on the v6 section.
Then do yourself a favor and get a good catchcan. Easy to install. Again search the v6 section. I have the Mightymouse can, I think it's the best !