I have the p0300 problem with misfire in 5 gear at 60 mph. I went to and they flash my ecu. The car was running great with no codes and no misfire. I enjoy this for two weeks until that demon light turn on and i feel a decrease in power.

I notice that the boost reach the 19psi that i have set in my MBC not to fast. And if i am in the highway at 60 mph in 5 gear, sometimes i have to change to 4 gear because it loose power. I clear the p0300 code and it dont appear for 4 days but the loose of power remains. Mitsubishi will flash my ecu again next week and they will check the spark plugs. What else do you think i can check? The use of gasoline was incredible with this situation.

 

has anyone tried a lower octane fuel to fix the misfire code?

 

i use 93 octane for 2 1/2 years without problems until now.

 

you could get that creader from vishnu if the dealership cant fix it.

If it is an xede thing sorry, i dont know much about it, as i have never had p0300 problems

 

My God - use the search option!

 

i use the search option, read a lot about different post about spark gaping (i changed already), plugs wire (i changed already), i have mitusibishi fix and the problem continue. My evo has an actual misfire not just only the code. My car is stock because mitsu****si remove my dynoflash. I will not send the ecu to Al until they fix this because they will try to find motives to void the warranty. I know if you know something else about this you will help a lot of evo owner that have this problem.

 

Have you changed your spark plug wires? Plugs are only a portion of an ignition tune up.

 

Is it actually misfiring? A crank sensor can report false misfires.

 

i get the same code all the time...it got worse when i changed my plugs, and when its humid...i have the creader in at all times, and the code gets erased within seconds...you can get them on ebay for $50, or vishnu...

 

I have most threads on the P0300 subscribed. There is no universal fix it seems. Those that seem to work sometimes come back thousands of miles later - or much sooner.

Personally, with 50K on mine and the problem having surfaced with<4K, use a C-Reader and as it so happens will be putting on the Buschur COP ignition soon and will also be getting a full tranny rebuild via TRE or Shephard Racing soon. I'm hoping that one or both fix my problem and my bet is the tranny rebuild will.

I have a nasty vibration in 5th gear at <3K and it's been there almost since I owned the car but has become more noticeable higher in the RPM range - it used to be noticeable really only at < 2.5K RPM.

My conclusion from all the reading is it's harmonics - or vibration - SOMEWHERE in the drivetrain kicking off the sensor.

All of my conclusions are just mine and there are many other theories out there. It's a damn mystery or a holy secret nobody cares to share. I've lived with it for a long time - running in 4th gear until I'm at 65mph or higher.

But, again, this is just me - and my impression is there are a LOT of folks who are suffering and/or have suffered with this problem. I don't hear about it in the '05s much.

*Shrug*

 

So no one has answered my question. Is it really misfiring or is it a code that says it is?

 

i have the same issue and i don't believe it is really misfiring. it happens to me only in 5th gear when i accelerate gently at around 3k -3.5k RPMs. That is just way too specific IMO for it to be an actual problem with my plugs or wires or coils (all of which mitsu has replaced). It has to be a problem in the ECU with one of the sensors being too sensitive and a certain type of vibration that only occurs in that situation triggers the engine light.

 

bringing the life back to this thread. This EXACT problem just started happening to me, crazy loss of power and vibration at 3-3.5K in fifth gear, with the P0300. the only thing i could find while searching was spark plugs which makes no sense cuz it happens so specifically in that setting. anybody get any updates on fixing this problem? its really startin to **** me off...

 

I know it's long, but you might want to take the time to read through this thread:

https://www.evolutionm.net/forums/sh...ad.php?t=88937

There's a lot of info about p0300 in there and answers to questions that have been asked many times.

 

There is no magic fix for P0300, yet, no matter what Mitsu or anyone else say.
I still get it occasionally but only at idle (never get the code above 2000 RPM)
But I also get NO pulled timingand NO power loss.
It's just like a fly that I can't squash. I learned to ignore it :}

And for those to feel that you lost power, most likely you are developing a boost leak.
Test for it! and clamp down those hoses before looking for anything else.