God%@*& p0300 - need vehicle specific advice
 

So I just bought my evo about 2 weeks ago. It threw the p0300 randomly about a week ago, but i noticed no change so i ignored it, and it went away by itself. now, today it came on, and the car bogs like mad in every gear. it is just slow...definitely misfiring. since i bought it not long ago, the dealer said they'd cover it. they want to replace the coil packs and reflash the ecu. but the problem is i have a 2.3 with custom tune. here are my mods. thanks alot in advance.


'04
Stroked to 2.3L
Wisco pistons
Eagle rods
Walbro 255lb fuel pump
Knife edged crank
Buddy club cams 264/272
Fidanza cam gears
AEM intake
Turbo Smart electronic boost controler
Forge BOV
SS brake lines
SS clutch line
Brass shifter bushing
Short throw shifter
aftermarket clutch (I THINK its ACT)
SAFC II tuned by Mac in Parker CO


ayudame :(

Unless they've changed it, this handy little device resolves that problem forever. It's called the "CReader" OBDII scanner, and there are always several listed on Ebay:

http://cgi.ebay.com/ebaymotors/Cread...spagenameZWDVW

Just plug the unit right onto your OBDII port, and leave it there. You'll never get the nasty code or misfire again. Just keep in mind that if something else goes wrong, you won't get a check engine light or code, so you'll have to remove it to diagnose another issue.

so it eliminates the actual misfire as well? my car is running like ****. the idle is jumping, there's no power, and it sounds/feels like crap.

Yes, it eliminates the misfire as well. Strange, isn't it that the misfire is somehow a product of the code itself and not a mechanical issue.

Just leave the thing plugged in, and you'll never get the misfire or code again.

Hmm, I see. Not that I DON'T believe you, but...what kind of intelligent person would I be if I took the word of one dude on an evo forum? (even though you are a guru). I would just like a second opinion. I do appreciate your help. Does anyone relse have experience with this little gadget?

I have the same problem on my evo and it started TODAY- just bought a code reader and a bottle of fuel system cleaner. I have 40k mi on the clock but it is either clogged fuel injectors, spark plugs, or coil packs. I will do one at a time then clear codes as necessary to find the problem

In regards to the Creader, if I bought one how do I go about getting an inspection. Wouldn't the code come back after the Creader was removed?

The CReader only eliminates the code for a misfire. If you have a real misfire you need to get it fixed. Alot of evos throw a misfire code because of cams or advance timing at idle and it is not a real misfire.

A misfire can be the result of a number of things. Bad air/fuel mixture, bad spark, compression problems, cam timing, etc..... on the Evo it can also come from knock. Knock is bad for your engine so if enough knock is picked up by the knock sensor, the ecu will pull timing (to prevent/ stop the detonation that is occuring) thus causing your misfire, cel and p0300 code. A few evoM members have had p0300's and misfires that occured from false knock readings picked up by the sensor because of vehicle harmonics, which led them to other problems. Try getting a code reader, erase the code, disconnect your knock sensor and drive around the block a few times. If the misfire returns you know its an actual misfire and you can troubleshoot your air, fuel and spark system components. If it goes away, you know its knock that causes your misfire, whether it be real knock or false knock, and you can troubleshoot from there. Or just check your plugs and look for other obvious things that might be the cause. You can even search for p0300 and see if anyone else's problems and fixes might lead you to resolving your own. Im just saying to find out whether or not you actually have a misfire, or a misfire caused by knock and sensitive sensors before you start wasting your time and money buying replacement parts for no reason like I did.

Are you guys saying that the engine might read misfire after installing the cams, or when the timing is off?

Who did your tune? If it was Dynoflash or AMS or somebody they should have a copy of the dealer reflash and should be able to incorporate it with a custom tune. In fact I think I remember a long while back reading that Al will do it for existing customers for like $50 bucks or something. That was at least a year ago I read that though. From experience the dealer flash really works so I would try to find a way to get it and keep your tune without shelling out too much $$$ for another tune.

Huh, this Creader will solve misfire:confused: .....This little Gadget is meant to read code and delete them not solve the Etiology.

The Creader solved the actual misfire itself and the code as well. I couldn't go more than a few miles without getting actual misfire, which made the car undriveable. I discovered that leaving the Creader plugged in to the OBD II port solved that glitch completely.

Now, so long as nothing has changed with the Creader in the past 2 years (?), it has worked for me, and has worked for others. As to if someone chooses to believe me or not, I really don't care. I am telling you this for your benefit. Use this information as you see fit.

The End.

Thanks, I'm gunna try new plugs and a retune first, if that doesn't work out I'll give the Creader a try. BTW, my P0300 pops up within a few min of resetting, but my idle is lopey with the cams and hopefully a tune can help that out.

The misfire is somehow a product of the flagged code, not the other way around. I don't know the logic, and I'm not going to guess. When the code is cleared, the misfire disappears. Like I said before, go figure.

. . . Well ok, I will guess. My guess is that upon the code being flagged, the ECU resorts to some type of 'limp home' mode. This causes the engine to misfire, but gets you home. This appears to be unfortunately, an emergency measure for a condition that doesn't really exist. Circumstantial evidence points to transmission noise as being the culprit, and this is a shortcoming of the factory ECU and the programming therewith. The dealer reflash doesn't always fix the problem, but it can cause difficulty (if not an impossibility) should you wish to have a performance oriented reflash at some point, so be advised before you go this route.