Check Engine CEL
 

So it's probably the wrong section to post it and I apologize if so. I'm on my mobile phone doing this. It's raining pretty bad here in Houston, Tx and I went to get some food. I turned on my 8 and gave it a rev as I alsways do, though this time I revved up to red line however it didn't make it to the redline and it didn't bounce rpms like usual. Then the check engine cel starting flashing. I needed to get back home and the car idled normal so I slowly made my way home and after a few seconds after leaving the cel stop flashing and didn't reappear. Anyone have any idea what may be going on? I wanted to stop at an autozone to check code however the cel hasn't come back. I'm wonder if water may have made its way to my air box since its raining so hard with the wind. I have the revi air duct installed recently.

misfires.

I just hope that its because I put regular grade instead of premium as I normally do weekly. Also that the k&n air filter in my stock box got a little wet. The drive from work to home was smooth as nothing was wrong. No rain and I top off my tank with premium and a gas treatment. Would the misfires been cause by the lower grade gas?

Nothing to do with gas...

A friend of mine mention I could have carbon build up. :(

Also I had the code check and the history showed:
P0300: Random/Multiple Cylinder Misfire Detected

Should I do a de-carb?

when was the last time your plugs, wires, coils were replaced? wires could have gotten wet/moisture

well I had to get a new motor under warranty about 2 years ago. I know they replaced the coils, however, I don't think they replaced the the wires. Figure they would since the coils were white on the outside. I'll have to find the paperwork to see if the wires were replaced or not.

When you went to auto zone, did you mean there was no code?. There should be a code if you threw a CEL right?>

I have a unused front o2 if you are looking for one.

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NEVER use regular gas!

Did you ever get a chance to read the code?. It would be interesting to find out what happened?.

How many miles have you clocked since engine replacement? Maybe you should pull the plugs and check them. If they're bad and your wires were not replaced along with the coils then I'd go ahead and replace those too. IMHO, I believe this would be the cheapest place to start. Good luck

Research
 

Type in the code po300 and there are several threads on po300 code. I had a similar problem and replaced my coil pacs and while at it I changed out the wires and plugs, but the culprit you may find is your coil pacs. Mazda made a change of coil pacs as the 2004 coil pacs shorted out and prematurely wore out . Mine also had white residue from electrical action on its own housing. I replaced mine with BHR and no problems since. Good luck. type in the code and research... plenty of material here.