Check engine light ?

**pjm333** · 06-21-2015, 04:55 AM

2013 Camaro ZL1 Convertible...Check engine light has gone off 4 times, first & last time the light stayed on but the second & third time it went off a short time later. On the second & third time I noticed it said "check stabilitrak" Brought it to the dealer after the first time & they just reset it & said they could find no problems. Brought it to another dealer after the last time and they had the car for 5 days & they still cant figure out why it is going off. Onstar told me the code was P0300, random misfire.
I had the dealer list the steps they took to fix the problem,

"As far as your check engine/stabiltrak lights coming on, we have not been able to find any cause of faults. The following codes were pulled from modules.
P0300 (random misfire detected)
We checked ECU for latest updates all are good. Checked all spark plugs/wires. Checked for any vacuum leaks, none found. No leaks, compression is at GM specs. The supercharger "special policy 13313 " may be a factor but we are unable to warranty that procedure at this point in time. The supercharger does not have the slop in gears in order to replace it under GM warranty. When it does we will be able to do that job for you at no charge.
U0401 (electronic brake control module invalid data received from engine control module). This could have just been a glitch between two computers trying to communicate to each other. It is set as a history code and has past last ignition cycle test. This may have caused a random misfire code P0300.
Diagnosis not found.
Recommendation - continue driving vehicle and if either lights come on drive straight to dealer and leave engine running till a certified GM technician can inspect visually/GDS."

Anyone have the same problem ? Thanks !

**pajeff02** · 06-21-2015, 05:17 AM

A random misfire can be a lot of things. Poor electrical connections, ignition wires, spark plugs, fuel pressure (pump or filter), and vacuum leaks are the principal causes for this code. In addition, a dirty or malfunctioning MAF can be an issue as well if the air/fuel mixture is going lean. Does it happen at any particular time, ie. light cruise, WOT, or under heavy acceleration? How about a bad batch of gas that may have some water in it? Certainly would not hurt to change gas stations and run a bottle of Chevron Techron through the tank.

**pjm333** · 06-21-2015, 05:44 AM

I did try 3 different gas stations & it happens under normal driving conditions. I will give the Chevron Techron a try. Thanks pajeff02 !

**pajeff02** · 06-21-2015, 06:20 AM

Ok - let us know what happens and if the code keeps coming back.

Unless they have changed it, misfire detection is based upon sensing rotational forces on the crank. As each cylinder fires, it adds force to the spin of the crankshaft. When a cylinder does not fire, that force is not present and this is what triggers misfire detection. Based upon the degrees of rotation that the misfire occurs at, the PCM can identify an individual cylinder that is acting up. In a random misfire, it thinks it is seeing multiple misfires across more than one cylinder. Would not hurt to check the spark plugs and ensure that the ignition wires are all properly seated. You should hear/feel one "click" at each plug and two "clicks" at each coil pack.