P0300 help for someone in Italy

[Frissby]

Here is some info to get you aprised of my situation, I hope you guys can help me out:

I am from California and am in the military. I bought my EVO new last February when I was stationed in Lemoore. As soon as I finished the break in period I had a Greddy Prof B Spec II boost controller, HKS cat-back, and Autometer boost and oil pressure gauges installed. Not long after that I got a SEL so I took it back to the place that installed my mods to have them check it out. They said it was a P0300 code which meant, of course, random engine misfire. This was in March or so of 2004 so that didn't set off any light bulbs in my head because I still had no clue the magnitude of the P0300. They reset the code for me and I was good for a couple of days but it came back (along with the 5th gear cruising vibration that you have to let off the gas and get back on it to resolve, temporarily of course). Then I started having a worse problem, couldn't boost past 12 psi, so I went back to the shop again and had the boost controller removed, thinking it had something to do with that. Still couldn't boost past 12 psi. So, I took my friend's advice and took the car to Vishnu to get their flash (and downpipe and hi-flo cat). Once there, they flashed it and took me for his famous test-drive in my car, he couldn't get it to boost past about 12 psi either, so once back at the shop they trouble shot and figured out that I had probably been running too much boost with my boost controller and had ruined my coil(s). They replaced those and Shiv was able to drive the car boosting it at a consistent 21 or 22 psi. So I left happy. You see, I had the P0300 but it was totally unrelated to the coil problem, but I didn't know that at the time. So I drove back to Fresno and about half-way there in 5th on the freeway going about 80 my SEL came back on and it started to sputter, no accelloration, until I let off the gas and got back on it. So a lot of time passes by and I just live with it because I am hearing and reading about all of the horror stories about people going to the dealership with mods and having their warranties voided on the spot. So I ship the car to Italy because I am transferring and figure I can just park it for three years and worry about it when I transfer back. So basically I guess my question is, if I want to fix this problem myself, without the help of a dealership, since there aren't any here that I can find on the Internet, how would I do it? I have seen people say that you need a new transmission, I have seen people say that a stand-alone engine management computer would fix it, and I have read that it's possible that pistons might be bad. I am not worried too much about voiding my warranty because I am at 35000 miles now and will be here for another 3 years, I just want to fix the car so I can mod it more, but it would be pointless to mod a car that will throw codes and screw with my timing, because when my SEL is on, I swear it feels slower than stock. So anyway, that is my story, sorry it was a book, but I really want to fix this problem, it makes me so mad sometimes I want to drive the thing into a wall and end us both, not really, but you know my pain. Thank you. Christopher Frisby.

[chrisw]

you need to get the ECU reflashed.

While your in Italy, I would reflash it to run on the gas they have there, then do it again when you get back.

you might also contact works or any of the other tuners who sell mail-in ECU reflashing to see if they have a fix as well.

[Option2]

Well unfortunately the new fix Mitsu came out with doesn't fix the problem. In short, there isn't really anything you can do. I recently went to the dealsership to get the "new" P0300 fix and went over to WORKS to get the P2 put back on my ECU. On my way to WORKS the P0300 CEL came back on. You'll just have to wait until Mitsu figures out a fix.

[vtluu]

I get a P0300 once in a while. I haven't bothered to get it fixed; I just keep an OBDII reader in the glovebox and reset it as needed.

Note that Mitsu's "fix" for the P0300 is simply to make the ECU not throw a P0300 so often. So it really doesn't change anything about the way your engine runs.

[GokuSSJ4]

if you can get some one locally to tune a standalone , than i would choose that route. Either EMS or what ever other things they have available in europe.

[300kpa]

I think Mitsu fixed the P0300 problem for idle. At least it fixed my problem after they flashed my ECU AND replace some new fuel injectors. It never came back since the injectors were replaced.

But only 12psi of boost sounds like one of your boost line was loose. The default mechanical wastegate setting is about 10-12 psi, and it will be what your boost will be if one of your boost line that gose to the boost solenoid was pop'd off.

[Absinthe]

if you can get some one locally to tune a standalone , than i would choose that route. Either EMS or what ever other things they have available in europe.

Motec or Haltec are the options what you really want to do is get on the lancerregister board and ask the brot boys what to do there are a couple of nice evo shops in the uk and they have been working on the cars longer than most people here have know it exists. evo400 is one of the shops.

[Option2]

I think Mitsu fixed the P0300 problem for idle. At least it fixed my problem after they flashed my ECU AND replace some new fuel injectors. It never came back since the injectors were replaced.

But only 12psi of boost sounds like one of your boost line was loose. The default mechanical wastegate setting is about 10-12 psi, and it will be what your boost will be if one of your boost line that gose to the boost solenoid was pop'd off.

I have that problem....P0300 at idle. After the "new" fix, I get the CEL while driving now

[Frissby]

I think Mitsu fixed the P0300 problem for idle. At least it fixed my problem after they flashed my ECU AND replace some new fuel injectors. It never came back since the injectors were replaced.

But only 12psi of boost sounds like one of your boost line was loose. The default mechanical wastegate setting is about 10-12 psi, and it will be what your boost will be if one of your boost line that gose to the boost solenoid was pop'd off.

I don't get the boost problem anymore, that was a coil problem that Shiv figured out, so he tested another coil on my car and it boosted fine. The P0300 is my current problem, and if it didn't mess with how my car runs I wouldn't worry about it until I get back to the states, but in 5th on the freeway, cruising at around 3500 to 4000 (75 to 80 MPH or so) the car starts to vibrate and won't hardly accellorate, but if I let off the gas and get back on it goes away. So if I find a local tuner that could tune an AEM EMS w/ UEGO would that be the way you guys would go? I mean, I do plan to do cams, gears, and turbo kit when I get home so the EMS would be one mod that would be out of the way when I get home, but I really want it to fix the P0300 now, that thing is pissing me off. Thanks guys.

[EVO GRIM]

I get the same missfire with the code, but pretty rarely. The scary thing about standalones are the lack of safety that the ecu gives. I just clear the codes for now. Alot of people blame it on gas too. What octane can you get there?

[300kpa]

I don't get the boost problem anymore, that was a coil problem that Shiv figured out, so he tested another coil on my car and it boosted fine. The P0300 is my current problem, and if it didn't mess with how my car runs I wouldn't worry about it until I get back to the states, but in 5th on the freeway, cruising at around 3500 to 4000 (75 to 80 MPH or so) the car starts to vibrate and won't hardly accellorate, but if I let off the gas and get back on it goes away. So if I find a local tuner that could tune an AEM EMS w/ UEGO would that be the way you guys would go? I mean, I do plan to do cams, gears, and turbo kit when I get home so the EMS would be one mod that would be out of the way when I get home, but I really want it to fix the P0300 now, that thing is pissing me off. Thanks guys.

I don't know, but it sounds like a real "misfiring problem" to me. May be somewhere else in your ignition system cause your old coil malfunction? And now your car doesn't run well because it is really misfiring? I would check the spark plugs and the ignition wire if your coils are new and fresh. May be your wire to teh coils have shorted circuit somewhere? Just a guess.

Make sure you have new plugs after you replaced your coils, your old plugs might have fouled because of teh bad coils.