Le Mans: Prototype Class
Join Date: Jul 2007
Location: Oklahoma City, Oklahoma
Re: P0300 random misfire
do you have any low speed issues? Like hesitations misses etc. Not stuff you can necessarily hear but feel? Like jerks slight odditites? I would recommend taking off the BPV and replacing stock until the issue is solved. But that is what i would tell you if I were at the dealership. The reason I ask about the low speed issue because an EGR could cause this and since it is a Ford design it does have EGR runners built in the intake. If it were a faulty IAC you would be having more issues than a little hesitation and stumbling at idle.
after the vacuum hose spray down, like I mentioned earlier, if nothing is leaking from that, then replace the BPV with stock and disconnect the battery and touch the cables from the car together( Only after disconnecting the battery and being no where near it. This will reset the memory completely not just the immediate memory. It will discharge the stored voltage for the keep alive computer memory. In other words a complete refresh. Most people do not realize just disconnecting the battery doesn't reset the entire system. Just like the battery in your computer for the timing circuit. It will not hurt the ECU to do this but it will reset all Fuel trims etc etc. Leave the battery disconnected over night. In the morning the vehicle may start funny but it's ok I assure you it happens. It will then go through idle relearn, STFT, LTFT reset etc. etc. etc., then we will see what happens.
With a Scan tool and being there I would've fixed this days ago but, I'm not there and I can't see live shots of your ECU data.
-CoolGuy stickers, mad awesome bright lights, blackedout lenses, super wicked general tires I got from Sears for forty dollars, some random size shift boot, mad skillz shift knob with fake carbon fiber. This is the stuff you put in your sig when you have nothing done to your car but you want to feel kewl with your wire wrap and neon LED underdash lights.