2011 Camaro ss mt misfire 303

[rcjohn9085]

I have a computer and came back with misfire in cylinder 3. I erased it and double checked. Autozone did it as well and got same issue.

So my problem, the car check engine light comes on randomly, as well as service stability track. The car itself always seemed to start hard, where it doesn't want to crank over but than it does, it doesn't take much longer than starting any other car though.

Info about car:
Got used from dealer with 10k miles on it last summer. Put 10k more on it. Had to replace battery after a few months. Also, the rear center brake light is out, and I have to replace that. When we first got it, tpms was a issue for a few days, but than fixed itself. Parking assist was also a issue, it didn't work, but after I disconnect battery randomly one day, it fixed itself. However it was like this for months.
I added a stereo head unit, reverse camera, kn intake with the ram air.
Other than that, nothing else.

So what I did to fix current issue:
Replaced all plugs with ngk, and still have bad code.
I tried changing plug wire from 1 and 3, but 3 still shows misfire

So what next?
I bought extended warranty from dealer, if I use them, I won't get my $1800 back. So I'm trying to check as many things as possible before I bring it in.

[JerTM]

Swap the coils around to see if the misfire follows. If it doesn't then either you have an injector issue or a compression problem. Get rid of the NGK plugs for a delco plug.

[rcjohn9085]

Thanks for reply

I am going to try coils today, if still a issue in going to get a compression tester.

Do I need to remove all the plugs to test just the one cyclinder?
Or just cyclinder 3?

And can I just get away with removing the fuel pump fuse and ignition module(or whatever is distributing the spark to the plugs)

[rcjohn9085]

Swapped coils, still throwing cyclinder 3
Doing compression soon

[rcjohn9085]

Compression was about 190 for all 8


Sooooo yeah.

[10 Silver Bullet]

that's weird I would stay on the dealer about fixing it if you still have warranty

[rcjohn9085]

Spark plug from that cylinder was dark(these are brand new and the rest are clean)

Not sure if oil or if burnt. It didn't seem real whipe able, so maybe fried rather than oil?
Ignition electrical or fuel injector issue win this cylinder?

[rcjohn9085]

Switched fuel injectors, didn't fix it

So thinking either electrical with the injectors or spark plugs(prior to coil), which I could fix if I knew where to begin

Unless it's a piston or valve issue, which I am not capable of fixing

[Night trained]

Do a cylinder leak down test. If ok pull that odd bank v/c and check valve spring.

[hunter1660]

I've got bad plugs out of the box before....might try a swap

[JerTM]

Ok. You've eliminated a coil , plug, wire, injector, and compression. A very dark plug could be oil or excess fuel. Can you get a pic of the plug? A quick test for a coil control problem would be to disable the injector for cylinder 3 by unplugging it, pull the plug from the cylinder and put it in the wire, let the plug touch a good ground and start the car. you should see a decent spark. A cylinder leak test would be the next item to try.

[JerTM]

Originally Posted by Moreair1

Have you checked your 02 sensors are operating correctly

O2s will not cause a misfire on one cylinder.

[JerTM]

Originally Posted by Moreair1

http://www.obd-codes.com/p0303

My college education, GM training, and decades of experience is all wrong. It's on the internet.


OP, don't bother autozoning the o2 sensor, it won't change the misfire on a single cylinder.

[Soybeanrice]

Originally Posted by JerTM

Ok. You've eliminated a coil , plug, wire, injector, and compression. A very dark plug could be oil or excess fuel. Can you get a pic of the plug? A quick test for a coil control problem would be to disable the injector for cylinder 3 by unplugging it, pull the plug from the cylinder and put it in the wire, let the plug touch a good ground and start the car. you should see a decent spark. A cylinder leak test would be the next item to try.

I didnt see where he swapped the plugs or put in a new AC delco plug ... All I see is that OP inspected it and said the current plug was dark. Picture of the plug would really help.