hey guys, i've searched the forum and google for awhile about p0300 on 03' evo 8's and havnt found any straight awnsers, so i guess ill ask for my self.

i went out of town a few weeks ago and while driving at 75mph for 20+ minutes my CEL came on and my car started to cut out. when i take my foot off of the gas and then back on it would go away for a few seconds then itll do it again.

i replaced my spark plugs and bought a spark tech COP system off of evom.net last week.
i all have a DW320lph fuel pump that i installed last year.

about two months ago i did my timing belt and new balance shaft belt. my friend bent my crank sensor plate and it nicked my crank sensor a little, but i quickly replaced just the plate. i havnt had any problem with the crank senor or anything.

and while driving out of town again my CEL came on and started the cutting again.. it only happens when im about 70+ mph for a few minutes straight.

any ideas???
or should i just delete thew code all togeather??

 

What plugs are you running? And what gap are they at?

What power mods? And boost are you at? Do you have a wideband, what is the afr at the highway speed?

 

I don't see why mods would matter if I'm just driving normal.
I gots ets 2.5" short route piping, a cone filter, fuel pump, spark tech cop, off brand intercooler, 3" dp, test pipe, and cat back, I also have a six puck and lightweight flywheel.
I am running bpr7es gapped at .24 I think
I'm at 18lbs or boost
Regular driving I sit at 14 - 15 afr, idle is the same. WOT I go from 12 down to 10( kinda rich lol )

 

Random misfire, it's happened to me before on a few occasions. What I did was gap the plugs to .022 and check the coils to see if they are seated properly. I have scanner in my car so I just erase it, if it keeps happening just have a tuner disable it. Its weird that it happens to you even with a c.o.p

 

You should try one step colder plugs. Br8es they are ten dollars. Gap then to .022. When I had that code it was shortly after I installed my COP. I switched to the NON protruding tip NGK plugs and also went one step colder. Fixed the issue, almost a year now.

 

I thought bpr7es was colder than br8es??

I do also have a tad bit of play with the coil #1, but I don't think it's much of an issue lol

 

Find someone with a tactrix cable and disable the p0300 code from coming up again. I had to do it on my car and no issues anymore.

 

So if I delete the code then it'll never sputter again??
And is br8es colder than bpr7es? Or the other way around?

 

Yes, I haven't had any problems since disabling the code in the ECU. I had the same exact issue, crusing on the highway and I would just be accelerating and it would all of sudden feel down on power almost (when the code was thrown). Would have to pull the negative cable off the battery to reset the code and all was well again. Now I never have to worry about it again.

BPR8ES is colder than 7ES, yes.

I'm personally using BR8ES plugs (non-projected) on my car and running great.

 

I personally would try the br8es plugs ( yes those are colder than br7es ) I wouldn't delete code just yet. Try the different plugs and gap before disableing the code.

 

I still had to disable the code after switching to these plugs (just sharing my experience).

 

my thing is what if you are misfireing and you disabled that code and now your getting knock and detonation and next thing you know boom goes the motor.

my personal preference is to try and fix the issue before turning off CEL's in tephra.

but theres more than one way to skin a cat.

 

Search P0300 on this site and you'll return posts back to 03 when the car hit the states.

Mitsus answer was vibration through the drivetrain and two rom updates. Nowadays tuners just disable the code routine within the rom. Never to return again.

Some things to look at

-Ignition components (You will usually get a specific cylinder code if this is the case)
-Idle timing too far advanced in the ignition map
-large jumps between cells in either ignition or fuel mapping
-drivetrain harmonics

If all exhausted have your tuner disable the P0300 code routine in your rom and call it a day

 

I disabled mine 3 or 4 yrs ago. No issues from it. The code being thrown causes the car to enter the limp mode in which it begins to studder. If there is no basic issue causing it then turn it off.