Wow, in the last day its getting worse.

Stumble after 3k under any kind of load. Press on the gas and it gets worse.

Funny thing is the first 5000 miles were golden, no problems at all. That makes me think something is broken?

I have no mods at all.

 

"Stumble" is a new term to me, can someone please define? thx

 

Stumble - Is a description of a random lack of power usually attributed to the car missing either from lack of spark or fuel.

If you ever have had bad wires, you have experienced stumble.


The car would sound and feel like

mmmmvrrrrrrrrrrrrr poom poom vrrrrrr poom vrrrr poom poom vrrrrrr poom poom poom vrrrrr

 

If your getting a stumble, before you get too concerned, replace your plugs.. thanks to our cars running rich, and the cold dense air, its entirely possible your plugs are fouled, or the electrode or gap is "out of spec". This could also be the source of misfiring under boost/load..

HOWEVER if everything is fine, and you still get random misfires AND you get the CEL, then the OEM Reflash may help.. Keep in mind that it OVERWRITES ANY REFLASH ALREADY ON YOUR CAR.. and depending on what portion of the ECU gets written to, the flasher (Dynoflash, works, etc) may need to get an new extracted flash source for the new Mitsu Flash so they can reapply their changes to it.

Oddly enough, I've NEVER gotten a CEL, but I do get stumbling and it started one day and has been there since then until I replaced the plugs, even though Mitsubish said NOT to replace my plugs that their good for 15000-20000 miles..

 

I had the "random misfire" PO300 code 4 times now, one before anything was done to the car and now three more times, once after just the Xede was in, and now the last couple with the Vishnu turno-back exhaust in too. Two came on during lift off after a cruise/passing situation, one came on at idle, one at about 40 mph, I think in 3rd gear.

I was informed yesterday, that at least in my particular situation, that my O2 sensor is thinking it's overheating and then the code is thrown. It has nothing to do with any mods and it is a known problem with the stock ECU. The service manager at the Sycamore, IL store is hopeful the fix with be out with the next ECU flash disk. He stated they come out about once a month and they just got the last one a few days ago.

 

Just call dynoflash. You don't have to wait untill gets their **** together.

 

Our flash equipment we have here does not have the ability to see the ecu code or change it manually. Only reflash whatever the new setting that mitsu sends us. At this time there have been no rumors of mitsu coming out with a new flash for the EVO.
Atleast not to my knowledge.

 

Hmmm. The dealer had my car for 4 hours driving it around is it likely that they missed something easy like plugs?

I feel like it is getting worse so I might take a look at them as the car was running great until recently.

Thanks for the response everyone.

 

The dealer changed my plugs/wires/coil packs.....still getting the 0300 CEL.

SC~

 

Has anyone here pulled out the plugs and checked the gaps themselves?

 

excellent discription. LOL LOL

 

I pulled the number 1 and number 3 (or 2/4 if you go from the right) as they did not require unbolting the coil packs.

They both looked ok. Carbon on the base, but the electrodes looked ok. The number 3 was discolored toward white, but otherwise ok.

The plugs are kinda odd. I haven't seen one with the extra piece on the ground electrode like ours and the electrode seemed very sharp (or maybe just burned away) and thin.

Didn't seen any problems with the wires or connectors, the high voltage side looks very short in distance.

What would the symptoms be if there were a hole in the intercooler?

 

What I meant by checking the plugs is checking their gap. That's the most important thing to look for on the plug aside from how they look. If they aren't correctly gapped they'll misfire under load.

Here's the weird part. The service manual specifies a minimum gap of .028, but that may be incorrect. There have been many people that have reported plug gaps that were off. The best gap or gap to run that seems to work without mis firing is .024 as has been noted by many. I looked at my stock plugs and they were all at .024, which is why I thought it was weird that the service manual spec'd a minimum of .028. Anyhow, my car has never thrown a CEL. My advice to those that are having mis firing codes is to check their plugs and gap them to .024 if they're not. This is something that can easily be overlooked and easily fixed.

 

The shop manual states .028-.031 while the owner's manual states .024-.027 for the gap. I checked mine and they were all .024 and I have not gotten any codes. However, I changed them to .028 because that's what I always run

 

sounds like you have cams ,
It seems that the early models of the Evo seem to have all of this problems .Since also the Evo is new to the states , you get all of this small bugs to be work out out of the car...