started my car this morning, and the cel was on. got it checked and it came up p0300 multiple cylinder misfire. i was told this is normal for a cammed evo to misfire every once in awhile but that doesnt make sense to me, especially with a tune. however the tune was done in texas and the car is now in wisconsin.

also, it was extremely cold last night, around -5 with the windchill, and my car was hitting fuel cut, could this have something to do with it? should i change my plugs right away? they are currently ngk 1 step colder.

 

It's because you have cams. A lot of people, me included, just disable the P0300.

 

My car never had that gremlin with cossies for a long time, then out of nowhere I would get a p0300 every start up. I ignored it because I knew it wasn't the plugs, and would do it every single start up. I finally disabled the p0300 cel in my latest rom. I wouldn't sweat it.

 

Was tuned in warm weather. maybe that's the issue, its the comp adjusting for this?? use the SEARCH button, to check this out more. I went from never having a misfire, to IMMEDIATE misfire after I pulled the car off the dyno for a test run.

 

any fix how to disable the misfire code??

 

Yes, there is a periphery bit disable that removes the P0300 check. Search in the EcuFlash section, all the periphery bits and address/table locations are the same for 8's and 9's (since you didn't list what year you have). Just disable the proper bit, reflash, and drive.

You might also want to adjust your fuel cut point as well, as repeated hits off that will trigger the P0300 as well. This is a pretty common thing, so you're not alone. I used to get it every 3-4 hours lol.

 

yea im gonna go with bigger injectors and a retune as well. cant even do any wot pulls now without it sputtering, i keep it out of boost for now. its 20~ish degrees out here

 

I ran 1000cc injectors and E85 all year with no problem. Now I switched to pump gas for the winter and I've started to get the code at startup. Stock cams and the car runs perfectly... jus keep getting the code.

 

yea the code went away and its still stuttering alot up top, so new plugs are goin in tomorrow. any idea what i should gap them at? stock .032(?) or what?

 

I gap mine at .026" usually, depends on how much boost pressure you run though.

 

i had a ses light on for a little while and checked it last week and had 3 different codes. the po300 random misfire, post cat 02, low fuel flow. i fixed the 02 in my test pipe with a speed element non fouler fix, and replaced an exhaust gasket. thought everything was fine drove 105 miles and my ses light came on again. checked it out last night and im getting the same 300 random misfire code. im replacing my spark plugs today at 33k miles on the car, ams told me thats what the problem is and its common, especially on cammed cars. also at the shop where i work my mechanics said becasue my 02 didnt have a non fouler in the test pipe and was reading high exhaust flow it burnt up my spark plugs. im hoping after i change plugs today i wont have this problem anymore :/. thats my story well see how it is after i change my plugs and hopefully my light will stay off. i recommend getting some OE plugs for your car and gapping them properly and that should get rid of any random misfires 99% of the time thats what ams told me.

 

so i shouldnt go 1 step colder? its tuned on 23 psi btw. when i picked it up 2 weeks ago, it already had the 1 step colder installed, not sure what it was gapped at though

 

what i did tonight was get a set of OE plugs for my car from the dealer and gapped them to .028 that car runs alot better. well see if the ses light comes on again for misfire :/ i hope it stays off. ams reccomds running OE plugs for your evo only no matter how built it is, and gapping to .028 if your boost is turned up from the stock 18-20psi depending on which evo you have.

 

plenty of p0300 threads on here

please search before starting a thread

 

I had started a thread a litle while back.. good to hear i'm not the only one!! haha

what are you running for cams? 272 or 280?