# P0300 code after replacing spark plugs and coil pack - 2015



## Rakaro (Jul 26, 2021)

Hey guys,

My car one day decided to bring up a P0304 code (Cylinder 4 misfire) and enable the stabilitrak + traction control nonsense. 
As usual, I replaced all 4 spark plugs which did not fix the problem because I did not notice the coil pack was missing its fourth metal contact due to corrosion.
I then ordered an aftermarket coil pack and replaced it.
I now have a P0300 code (Multiple misfires detected) which isnt as bad since it doesnt show up as often and doesnt enable the stabilitrak nonsense.
Are the misfires from the new spark plugs getting ruined by the old coil pack? or am I a dumdum for getting an aftermarket coil pack?

Thanks


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## Mr_Pat (Mar 7, 2021)

How's your ground wire looking? Double check your plug gap?


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## Rakaro (Jul 26, 2021)

Mr_Pat said:


> How's your ground wire looking? Double check your plug gap?


Sorry for the late message, got caught up in life.

The ground wire looks fine, but how would i check the plug gap? Should I take each plug boot off and push it down on the plugs individually?

Thanks again.


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## Blasirl (Mar 31, 2015)

Rakaro said:


> Sorry for the late message, got caught up in life.
> 
> The ground wire looks fine, but how would i check the plug gap? Should I take each plug boot off and push it down on the plugs individually?
> 
> Thanks again.







https://static.nhtsa.gov/odi/tsbs/2016/MC-10112283-9999.pdf

Tips to ensure no misfires occur:

Remove the coil pack. If the boots are stuck on, use a small screwdriver or pick with some dielectric grease on it to go around the outside of the boot and then possibly the inside of the boot to help aid in removal.

Remember to (p)re-gap your plugs to .028, (0.24 if tuned)

*Set gap with the black portion of this tool.*










To increase the gap size bend the ground strap up to the desired height. DO NOT LET THE GAPPING TOOL TOUCH THE *IRIDIUM* CENTER ELECTRODE OR PORCELAIN.

*Measure the gap with feeler gauges.*










*Throw this away.*












Torque to 18 ft-lbs with no anti-seize on the threads of a stock type plug.

Ensure the boots have no rips/tears or holes in them, lightly coat them with dielectric/silicone grease and make sure the resister springs are clean and not caught up in the boots when you install them.

If the plugs look bad, consider these:

*-BKR8EIX-2668* (iridium plugs), ~$25, expect ~10-15k regaps on these, ~40-50k overall life.
*-BKR7E-4644* (nickel/copper plugs), ~$8, expect 15-25K out of these plugs, with a regap or two required at 5-8k intervals on stock tune.

Read _Hesitation Gone!_ for more info on the plugs.






A good replacement coil is the MSD Blaster OEM Replacement Coilpack 8236

How-To: Remove and Replace the Coil Pack and Spark Plugs.

While you are in there, if you have a cheap endoscope, look at the pistons. This can also tell you many things.


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## Rakaro (Jul 26, 2021)

Blasirl said:


> Tips to ensure no misfires occur:....


Thanks for the many useful tips, I'll get a plug gap too land see if that's my problem.

Thanks again


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