Tandrus

Ok, my problem...

I have a lancer evolution 8 that has a mutliple engine misfire code (p0300) that comes in at around 3k RPM. The engine, when it comes in, sounds like it is running rough and if I accelerate,it gets worse. If I take my foot off of the gas, the reapply gas, it ges away for a bit (code still in), but then comes back. At WOT, it does not exhibit any of the issues that I can tell (hard to completely verify because I can't run WOT indefinately). Car idles fine. Problem typically comes in only at light or partial throttle and comes in at all gears (most evident in 5th as that is when I am tyically operating at partial throttle).

Already changed plugs, wires, boots. Unplugged MAF for a short drive and did not experience misfire issue (however, boost seemed to hang up and go higher than normal). I've checked front o2 sensor at idle and it appears to be in proper voltage range (0.62v).

Car has 93k miles and only upgrade is turbo timer. Pulling my hair out with this one....

Tribal

iTrader: (39)

did you gap your plugs correctly? did you check all your lines? are you experience fuel cut? what boost are you running and what type of fuel?

jsayers

iTrader: (3)

my cars did this too. from what i read its from extra vibrations. could be your balance shaft if youve had your timing belt done recently and it wasnt done correctly. thast what mine was from

Tandrus

Spark plugs were gapped correctly. Problem existed prior to plugs being changed out.

I'm running stock boost and 93 octane. I doubt it is fuel cut out as it does not occur at WOT. Only light throttle.

Timing belt has not been changed out.

I've checked hoses, but plan on checking again.

eSCAPEist_

I know it's a job, but if it is your balance shaft I would consider balance shaft delete if you ever considered a rebuild, It will be a costly problem if that gave way taking out your motor with it. I come from the DSM world of deleting probable causes.

gsrboi80

iTrader: (38)

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

Tandrus

Yah,
I had read all of those, ad thought it was completely drive train until it started coming in at 2nd-4th gears as well.

I'm curious if it is the crank shaft position sensor going bad....

I've cleaned the hell out of MAF sensor, that didn't do anything....

rhd-jon

iTrader: (11)

go tune it let them disable the code

steelfire19

iTrader: (5)

I have the same code, but my car runs fine when it pops up so i just had it disabled. Good luck tho.