So you're suggesting that the threory being put forward about the Knock sensor picking up the tranny vibration (harmonic resonance) and retarding timing or whatever its doing is wrong. The knock sensor has nothing to do with it nor do the tranny vibrations, but the fault actually lies in the ECU. Is that a correct assessment of your comments?

 

My car did it without any mods, it did it more with my turboback with stock cat, it did it less with my turboback with 3" cat (it no longer contacted the front subframe), it did it much more with the XEDE when the temperature here dropped suddenly. It hasn't done it at all in the last 5 times I've driven my car.

I've never experienced anything like timing being pulled, or any other untoward effects of having this CEL on, it does it while idling mostly - it pulls hard and very smoothly all the way to 7k. I wouldn't be surprised if the stock ECU has a problem, the Mitsu/Deno engineers aren't perfect all the time

 

What I'm saying is that the ECU is able to typically retard maybe 8-10 deg of total advance as a result of a knock sensor signal. Retarding 10 deg of timing will not cause the engine to run on two cylinders (which is appears to do when misfiring).

I'm not certain Mitsu even knows what causes the problem, but in two separate cases, it occurred to me after driving almost *exactly* the same distance on the Interstate. This hardly seems due to a transmission vibration, no?

 

I guess there are many scenarios being thrown here.
So I'll add another:
In my case, the misfire does not happen when the XEDE is DISCONNECTED.
Which leads me to think that the solution may be in the piggyback/ECU "area".

 

What's confusing here is that some cars just flash the code, while others experience an actual misfire.

Does anyone know of an instance where a electronically unaltered (stock ECU) car experienced actual misfire and/or an instance where an electronically altered (w/Xede or other) car just flash a code with no misfire?

 

It would be very interesting to find out that this whole thing is just due to a bad checksum in the code or insufficient ram/clock speed. Maybe some computer buffs out there could try some hardware re-working?

 

On a stock car, is it bad for the engine to keep getting the 0300 error code? Am i slowly deteriorating engine life whenever i get the 0300 error code and i reset the ECU myself to get rid of the SES light?

 

I've had instances when the light just came on (ECU with dealer reflash + XEDE), and no misfire. Although the norm would be a misfire/"stumble" at about 3000 + rpms, about 80mph....cruisin'.

 

Definitely seems like people have different experiences with the P0300.

1. No actual misfire but throws P0300
2. Actual stumble/hesitation aka misfire with P0300 or without throwing code

Either of the above can be continuous at cruising rpm around 3500 rpm in 5th gear etc or after a certain period of time during long highway drive.

Pisses me of to see so many EVOs with this problem and Mitsu not even doing anything about it. I feel that we are partly to blame as well. We all know that this particular misfire is NOT an Xede or any modification related issue, but as the car is modded, we're scared to take it into the dealership and would rather learn to live with it. I wonder how many people are doing exactly that. Cause if this is the case then there's no way for Mitsu to know this is not a rare instance and needs to be addressed promptly.

 

In my case it would be:

2. Actual stumble/hesitation without throwing a code

The car will only do this when cruising at around 3000 rpm (any gear), tip in the throttle about halfway and then let off the throttle completely (typical traffic scenario). Stumbles every time. It would be nice to have this explained, since I'm fairly sure it is a XEDE related issue, since the car has been doing it only since I've installed the XEDE. So far my "workaround" has been to change my driving behaviour and not cruise at 3K rpm, or if I have to, to not suddenly mosh the gas pedal just to have to coast again right away.

And, no, I have never gotten the P0330...

l8r)

 

Mine does that at idle. I'll just be sat there and it comes on, no audible miss - perfect driveability up to and after that point, like nothing happened. I clear it and move on.

My car does the exact same thing. The only thing is I figured my MR BOV was causing compressor stall that could be interpreted in the same way. The fact that you have the exact same symptoms as me convinces me more that it's the XEDE. I have adopted the exact same driving methods as you.

I guess we are all seeing two different problems making themselves known in exactly the same way, I don't know anything of how ODB2 routes trouble codes, but I would guess that a group of different conditions will trigger the same resultant code (given that there are multiple ways to influence a knock event - gas quality, spark advance, plugs, boost etc etc)

Shiv/David/Dustin - care to chime in?

 

I would suggest you try this first

a. Install your stock BOV and drive for a couple days and see if the misfire happens. If it doesn't then it's the BOV
b. If it still misfires take the Xede out and drive for a couple days

I'm sure that none of the 2 will fix your problem, which means that the problem is not with the Xede or the BOV but a Mitsu issue.

 

The key to understanding the problem is in understanding why the misfiring continues until the code is cleared with a scanner. That makes no sense to me, and seems to be rooted in the ECU.

 

You do have a point, but that may just be the case for a few people. From what I understand there are other people where clearing the code does not make much of a difference. They get the stumbling/misfire without the P0300 code

 

Mine stops misfiring the instant the CEL goes off when the codes are cleared. I know of no connection between stored codes and actual engine operation. If there is one (and apparently there seems to be), that's where the problem lies.