Random misfire

[Jesse2.0]

Okay guys I'm new to this and new DIY but hey there's only one way to learn right. Anyways I have code p103 p200,p300,and p400 from my dash trick thing. The engine light is not on and every time they hook up a scanner to my car no codes come up. So every 2-3 days I have a misfire and all but one time it happens when starting the car that one time was at a red light. Also not sure if related or not but the last two times I put fuel injector cleaner in my gas tank the car actually shuts off and takes multiple times to start the car.


Ford focus 2003 spi SOHC LX
What I done: fuel filter, air filter, spark plugs and wires, pcv valve, and two small vacuum lines that connect to two nipples on the firewall.

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[superfordzx3]

I'm guessing you mean p0103, p0200, ect... P0103 is for a MAF sensor, anything from wiring, sensor, or worst case PCM. Cant find anything for a P0200, but starting with P0201 are throttle body codes... P0300 would be your random misfire code. I have seen MAF sensors cause a random miss, exspecially if you have K&N oil on them.. And P0400 is an EGR code. Sorry can't give anymore detail then that, but hopefully it'll point you in the right direction.. Some aftermarket scan tools will only give you current codes, but if there's some in history, they wont show. Anyways, hope this gives you a start!

[Jesse2.0]

Thanks. Yea I hate just throw parts at it but either way those parts need replacing. I'm at 136k miles right now. I'm going to test the coil pack to see if that's it.