Issues with 2010 Camaro SS misfiring after spark plug & spark plug wire replacement

[Camarosmith]

Hello Everyone,

I have a 2010 Camaro SS with 140,000 miles on it & it's my baby.

The car was running fine although getting a little older with more mileage

I thought I would have some preventative maintenance done on the vehicle and so I took it to my local Chevrolet dealership.

The car was driving fine with no check engine lights on and no misfires occurring ever prior to me taking it to them for service

I go to pick my car up and the local Chevrolet dealership insisted I pay them first before they brought my car back to me which I did foolishly, hard lesson learned, see the results first before paying for the service. although they never have done me like this in the past.

So they bring the car out after I paid them after changing the spark plugs and it's misfiring with a check engine light on!

I parked the car and walked back in to talk to them and ask them why I now have a check engine light on that was not on prior. And the service rep then proceeded to say, " well let's scan the vehicle and check the codes! " He scan's it and finds that it is misfiring on cylinder 6 showing the P0306 code. He then proceeded to tell me that it was like that when I brought it to him.

I then clearly let him know it was not and was shocked they had the nerve to drive my car out to me that I wanted to do preventative maintenance to misfiring with a check engine light on and not even mention it to me that it was now misfiring after they worked on it.

He then said something about how I could leave it with them to look at further. I was done with them at that point. I was able to start the car up without it misfiring and drive it home. I then bought my own code scanner and have been working on it myself ever since as I do not trust the Chevy Dealership to work on my car any further after what they have done to it and their dishonesty and incompetence.

I notice the misfiring seemed to occur more often at startup when it was cold. I also noticed that the misfiring would occur intermittently while driving the vehicle. sometimes stopping and waiting a short while and starting the car again I could make it home without the misfire

Attempting to resolve the issue on my own I bought a set of 8 new
ACDelco D514A Ignition Coils part #12573190 on Ebay that are recommended for the vehicle and said to be OEM although round instead of the stock square coils and installed then, they seemed to fit fine however the intermittent misfire and startup misfire was still occurring.

The set of coil packs I bought on Ebay also came with new spark plug wires and also double platinum spark plugs that are also compatible with my vehicle.

Since I was still having issues after changing the ignition coils, I then installed the new spark plug wires on the car. This is when I noticed the Chevy Dealership never actually replaced my old ones I paid then and asked them to replace when I compared the old , but supposed to be new spark plug wires with the actual new wires I installed on the vehicle.

I thought at this point I had resolved the issue as the car was good without issues for about a week and a half driving it around and just when I thought I had resolved the issue it occurred again after a 30 minute trip on the freeway.

I was able to luckily get the car back home and it started misfiring just before I got home with it at this point.

So I then proceeded to replace the spark plugs that the Chevy dealership had installed with the double platinum spark plugs I got from Ebay with the coil packs, The Chevy dealership did actually replace the spark plugs and used the
ACDelco Iridium Spark Plugs 41-162. Upon replacing them I noticed only about 2 of the 8 that the Chevy Dealership had installed were actually gapped correctly. I noticed the spark plug on cylinder 6 was gapped at about .034 inches where I was getting the misfire. After I changed them all using AC Delco double platinum spark plugs I got from Ebay that came with my coil packs the car fired up without a misfire although the intermittent misfire came back while driving of course. The misfire also came back on cold mornings at times when starting the vehicle, but not always, but most of the time. After the engine warmed up it seems to start most of the time without misfiring. Also had less issues starting with the misfire when it wasn't very cold out in general.

I cleaned and dried my washable K&N air filter and cleaned out the air intake housing ridding it of dirt and debris that collected. I still have the stock air intake just using the K&N washable air filter in it I have had for the past 3 or 4 years without issues.

I have always used supreme gasoline only the entire time I have had the vehicle, mostly from Chevron. I decided to try some Chevron / Techron fuel system cleaner on my next fuel up thinking I could possibly have some type of issues with my fuel injectors. Although the owners manual said it's not necessary if you only use top tier fuel, which is all I've ever ran in vehicle. This didn't seem to help either however.

I then decided to put the Iridium spark plugs back in the vehicle that the Chevy Dealership installed the
ACDelco Iridium Spark Plug 41-162 and bought a brand new identical spark plug for the 6th cylinder I was getting the misfire code on & I checked them all carefully and gapped them correctly this time, unlike the Chevy Dealership!

I also carefully removed the throttle body and didn't mess with it and sprayed it with some CRC Throttle Body Cleaner as it was due for a cleaning and found this could be a potential culprit, when the car is not misfiring it seems to have a lot more power since doing this but still this didn't resolve the misfiring issue.

Still had issues with the car misfiring and the Stabilitrack light coming on at startup and intermittently while driving upon misfiring. however now the misfire shows it's on cylinder 2 and which had come on a time or two in the past but it was then mostly on cylinder 6 and only on cylinder 2 maybe once or twice along with 6

I then replaced the spark plug on cylinder 2 with a brand new
ACDelco Iridium Spark Plug 41-162 and am still having the misfire on cylinder 2 however I have not had an issue with cylinder 6 since.

I then bought a brand new battery to rule that out as my battery seemed fine although it was 7 years old and still the same issues are occurring.

One of the sloppy technician's who serviced my vehicle at the Chevy Dealership actually left one of the old spark plugs near my window seal under the hood of the car and it was the old stock ACDelco 41-110 like it says to use in the owners manual, however it's said they were discontinued and that the new OEM variant to use is the ACDelco 41-162

Also I would like to mention it took the Chevy Dealership 6 days to change my spark plugs and lie to me about changing the wires I paid to have replaced they never replaced!

Well at my local O'Reilly's Auto Parts store they had 8 of the ACDelco 41-110's in stock so I went and got them bringing the old 41-110 the Chevy Dealership sloppily left on my window seal / hood area to compare they were identical and installed them. However I am still having all the same issues with the stabilitrack light coming on while driving intermittently and misfiring on cylinder 2 occurring.

My next thoughts is to replace the fuel injectors along with the fuel pump that houses the fuel filter. I can hear all the fuel injectors working without skipping or anything weird, they may just be dirty however. What is strange to me is how was the car just fine until I wanted to have some preventative maintenance done to it by the Chevy Dealership and now I have all this headache and endless nightmare with the vehicle? I am also finding this can be caused by a vacuum leak or issues within the wiring harnesses. I have also read on here that someone resolved this issue and it related to a broken valve spring. I have had a valve spring break in the past and the Chevy Dealership quickly found that to be the case then and replaced it in then several years ago. However if it was a valve spring, why would it be all a sudden now after changing the spark plugs? & why would it switch from cylinder 6 to now cylinder 2?

It seems I am able to get the car to stop misfiring when I either pull over and clear the codes and wait a minute or two and then start it up, or sometimes I remove the spark plug wire on the cylinder with the misfire and then put it back and then the car starts back up fine again and I can at least drive it back home.

This is all so odd to me.

I contacted the Better Business Bureau as well as the Bureau of Automotive Repairs on behalf of the Chevrolet Dealership and whatever it was they did to my vehicle.

I mean they could have just been up front with me and said, " Hey after we changed the spark plugs, this happened " and we coulda gone from there, Not drove it out to me presenting it to me misfiring after insisting I pay them first. Also them having the stupidity to tell me it was that way when I brought it to them to add insult to injury.

If anyone has any information on any of these issues or has experienced them before, any advice would be greatly appreciated.

After my long journey with this when and if I find a resolution I'll be sure to share what it was.

[pyroguy]

First off, welcome to the forums! Sorry you're having issues with your Camaro.

I'll admit I skimmed through the story more than reading thoroughly, so I apologize if I missed something. To paraphrase, you bought eBay coil packs, new plugs, and wires. Misfire on cylinder 2. You took the car to Chevy, they replaced the plugs and put the same wires back on. You went to the auto parts store and got new wires. You're still having a misfire issue. If I missed anything please correct me.

What I would start with is replace the cylinder 2 coil pack with one that was previously working to be sure that isn't the issue, or swap that coil pack with one that is working and see if the misfire moves cylinders. If you're still getting the same misfire on the same cylinder, get a new plug on your own. It sounds like the dealer wasn't very careful and may have either installed a bad plug or damaged it during installation. Another very simple option is make sure the wires are fully and properly seated on the plugs. Sometimes they seem fully on but are slightly off. This will cause a misfire.

Good luck and let us know what your end resolution is.

[gtstorey]

Way to many reports of counterfeits on ignition parts on EBAY and Amazon. Never buy coils, plugs or wires there, especially to trouble shoot were you don't know what the problem is.

[NOT A 45]

Check the harness that's attached to the bracket the coils bolt to on the passenger side of the engine. We've had trouble with that harness mostly on trucks but it's the same harness.

[PaulsSS]

I have have a guess you may not like to hear but its happened to me so here goes. Drop Trans Am off at local chevy dealer for trans service. Next day I go to pick it up, start the car up and the engine is knocking! I freak out! I go back in and find the service guy and ask him what happened to the engine? He knows nothing! No body does! I try to drive the car home and discover both front rotors are CRACKED! Now these rotors were replaced 2 weeks prior to the trand service, noway they would be cracked. Both are BLUE and over heated. Till I get home(about 20miles) number 7 piston commits suicide! Have the car towed to another shop to get checked out car needs a new engine and rotors. Call chevy dealer and they refuse to help and know nothing!

Moral of the story? Make up any thing you can imagine. Bought the car new had it 12 years and 100k and 1 trip to the chevy dealer and its now JUNK!

Anything you can dream up could have happened to your car. 1st thing I would do is pull both valve covers and look for cracked springs. Running the piss out of a cold engine can break-crack valve springs and this can cause intermittent misfires.

I have a rule I never drop either of the Camaros off for service I always wait AND if the car needs to be driven out on the road I go along. If they refuse bye bye I go elsewhere.

I remember when we 1st bought my wifes Camaro the service guy made a comment, it went something like this. We brought the car in for "valve cleaning service" and the service guy said I lOVE THIS JOB I GET TO BEAT THE CRAP OUT OF YOUR CAMARO AND GET PAID FOR IT!

With that I told him off, got back in the car and never took it back for service!

[b3freak]

First of all, sorry to hear about your troubles. I've been down this road before. I know hindsight is 20/20, but IMHO you should have requested to speak with the service manager instead of leaving in frustrating and warming up the parts cannon. In my experience, you'll get a lot farther with management. Give them a chance to make it right and if they don't, THEN go to BBB, Google reviews, etc. But you need proof... solid proof or it's your word against theirs!

This day and time, it's best to take video of the car BEFORE you take to have it service or repaired. Inside and out verbally dating the video in front of the dealership. Heck, many dealerships do this themselves because of being blamed for damage. I always do a before and after video to show proof if some idiot damages the car or doesn't repair it correctly. Also, it good to show video of a scanner that shows readiness status to prove that codes were not cleared prior to dropping the car off. A common trick played on dealerships/service repair shops more than you realise.

Now, if I was speaking to the service manager, I would explain to this person that the service representative claimed the CEL was illuminated when the car was dropped off, but didn't have the courtesy to call you BEFORE any work was carried out. I would then ask for proof that his claim was true and not made up to cover their tracks. I would also explain to the service manager that you brought in a Chevrolet vehicle for preventive maintenance at a GM certified dealership with high expectation that the car would be in top running condition when picked up, but unfortunately, the car was returned in WORSE operating condition after being serviced by his team. Then ask him what he suggests to solve the problem. Again, you're giving him the chance to do the right thing. If he says, "Go pound sand!", then walk out and take the next appropriate steps. But if he offers a fair solution, then I'd take it as long as it doesn't require a lot of money. Just my 2 cents.

Now, IMHO, if you're getting a P0306, then I would look closely at the coil packs. My did the same thing and I replaced all of them and the problem was solved without the need to replace the plugs. The coil packs were cracked and in cold or wet situations, I would get a misfire and then the dreaded CEL. That would be my next step before replacing fuel injectors.

Good luck!

[anaya_malik]

Examine the harness that is fastened to the coils' mounting bracket on the engine's passenger side.

[Camarosmith]

Thanks for the welcome, replies and advice!

I took the car to a local shop that I have used in the past that has done good work and explained all the details of my long story here as I don't have much time to mess with it myself lately.

I agree with the advice on not buying parts on Ebay. I'll get the new OEM coil packs from a legit source if the problem remains in the future to rule that out as well. The car encountered the same issues after changing them is what I know thus far. But I'm still considering the coil packs

Moving forward I'm having the shop replace all the fuel injectors along with the fuel pump that contains the fuel filter with OEM. as the injectors are due to be replaced at 100,000 miles anyways, hopefully that resolves the problem if not they needed to be replaced anyways and I can rule that out as a factor.

I asked the local shop to check for any vacuum leaks as well as I have seen this is also a potential cause to cold startup misfires & misfires.

I have seen a lot of things through googling and around this forum related to the wiring harness as well so I'll look into that if problems persist.

I have seen that someone said they also had a broken valve spring also that related to there cold startup misfire issue. I have had a valve spring break while driving the car in the past and had the Chevy Dealership identify this issue and fix it in the past so this is another possibility I'm considering in this case.

[silversleeper]

I wouldn't do any ebay or amazon plugs coil packs or wires due to fakes.
I'd look at harness but especially an injector.
you can check that for free moving it to an easy to change position, like switch 3 and 6 and see if now #3 has missfire.
I don't like the dealers but not all techs are bad and did something wrong. I try to do my own maint and repairs to avoid the bad techs.

[Camarosmith]

ok so the local shop replaced the fuel pump and all the fuel injectors with OEM and I got the car back today,

unfortunately & as expected at this point the stabilitrack and check engine light is still coming on which hardly surprises me at this point However, when this happens now the car doesn't actually seem to be misfiring at all or at least not as bad still throwing code on cylinder 2 and the stabilitrack and check engine light will even go off on it's own now after coming on.

So although this seemed to help the situation it didn't resolve the issue and at this point I'm not surprised really, was kind of expecting it even

My next move is I'm going to just put all the old original OEM coil packs back on and see what happens

If it resolves the issue then I'm going this time all the OEM coil packs for a legit source that are identical to the OEM square Melco-Mitsubishi coils (12611424) ones I originally had that came with the car

I was having a hard time finding the original OEM square Melco-Mitsubishi coils (12611424) that originally came on the car and got the round Delphi coils (12573190).
also on Ebay but after changing them I had all the same issues as before with the original ones on

After that if I'm still having the issue my next thoughts are the valve springs.

Wow thought I was going to do some preventative maintenance on the vehicle and opened a huge can of worms, crazy how all these parts that were working just fine all a sudden have issues after simply replacing the spark plugs and wires a part of me feels like I shoulda just left it alone although it runs much better now and has much more power when it's not misfiring or flashing the stabilitrack so I guess that's a plus also since I'm at 140,000 miles with the car many of them were past due for a replacement anyways so hopefully I'm money ahead there in the long run.

[pyroguy]

Have you tried switching the problem coil pack to a different cylinder to see if the new cylinder gets your code? If so, then you have a bad coil. If not, then you have eliminated a possibility before throwing more money at it.

[PaulsSS]

A sharp tech should be able to look at the wave forms and get a pretty good idea what is causing the issue. It doesn't have to be a dead miss to toss a misfire code. Like I said cracked spring or even a cracked piston ring-land etc could cause enough variation in the wave form to cause the code to be set. May drive fine, I been down this bumpy road a few times.

[Joe.G]

Have you checked the harness? Some of the steps you have done just don't make sense to me, Its probably not the coil packs themselves especially since its still doing it even if they were fakes, Put Originals back on and just move them around to see if it follows same thing you should have done with injectors, If pressure is fine why replace fuel pump seems like shop is taking your money ( if they even replaced it )


Check the wiring harness I believe that is where you are going to find your issue, A weak valve spring could cause this as well but start with the wires as they could have been broke from moving when they installed the plugs.

[silversleeper]

I throw money at parts to avoid the dealer repair costs but try to make some sense of the process. I try not to buy fake parts in that process.


Replacing all injectors or ignition parts for one cyl missfire, or not checking fuel pressure and replacing pump and filter for one cyl problem doesn't make any sense as already mentioned.