Q: Dodge ram misfires only when I do a cold start?

asked by on February 07, 2017

When I first start up my engine in the morning I can notice the misfire and the engine light for cylinder 8 will come on. But after it warms up the truck runs smooth as can be and once it's warmed up if I turn the truck off and back on the engine light will turn off. I've done a compression test and they are all good and I replaced #8 ignition coil. What else could be the problem? I also know I'm using the wrong brand spark plugs... could that be causing it? Please don't recommend a misfire inspection because I've had you guys do that before and the mechanic was stumped.

My car has 124100 miles.
My car has an automatic transmission.

Hello, As you may know, there are a number of things that can cause a misfire ranging from faulty ignition parts to changes in air/fuel mixture, fuel pressure, timing an the list goes on. If you do know you have the incorrect spark plugs in the motor, I would start with changing these first as this can absolutely cause the motor to misfire depending on the heat range and resistance of the plug relative to what the factory calls for. This may be more noticeable when the motor is cold as the plug may be struggling to provide the correct flash pattern to ignite the fuel. Once the motor is warm, there is additional heat in the combustion chamber which may reduce the impact of the incorrect plug.

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