Pontiac Grand Am Spark Plugs Are Black

Pontiac Grand Am 2.4 L. Changed spark plugs. The car intermittently misses under normal driving conditions every once in a while. Changing the spark plugs makes it go away but a day or so later it comes back. The check engine light scan codes shows P0300 miss, that's all.

Answer: If changing the plugs helps, i would look closely at the spark plugs that were removed. Make sure they all seem the same color. If one is oil fouled, or looks a little greenish or orange, depending on which coolant is in the system at this time, this would indicate an internal engine problem. If one is totally black, this would indicate a very rich condition which may be caused by a faulty injector or ii more than one is black, then i would suspect a leaking fuel pressure regulator (FPR). If plugs look OK, you may have a problem with the ignition coil housing cover or one of the plug boots. The cover is the black plastic housing under the aluminum cover that you remove to replace the plugs. A meter check will sometimes indicate this housing is faulty. Also possible that the ignition module itself is stating to fail. A sticking injector is also a possibility. An fuel injector balance test may be needed. You need to find out which cylinder is misfiring when the condition is occurring. A scanner which shows live engine data stream is the best way to see this. That would at least narrow the problem down to which cylinder to concentrate on.

1996 Pontiac Grand Am.
2.4L four cylinder.
Repairs: Fuel pump.
Question: Oil in 1 spark plug hole? Why?

Answer: Most likely a leaking cam cover seal.

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  • Guest - Billy

    The help you gave me was great. I checked the plugs again and they had black sut on them and I also noticed a new symptom. The accelerator felt like it had pressure when you would start out but the the pressure would decrease alot. I replaced the fuel pressure regulator and now there is pressure and no skipping at higher speeds, also the hesitation at takeoff has gone away.Thank you.