I updated my ROM from 8 to 15 and and going to bring my plug gaps down from .028 to .026 and see how that works out.

 

Still no dice, the issue comes back, now that its cooler out it is more frequent too. I have 8 level plugs, i might go back to the 7's to see if that helps.

 

have you ever rebuilt the transmission?

there is a TSB out there for the 5th gear syncros in the '03 and some '04 evos. The gear assembly can cause harmonics in the same frequency range as the knock sensor when it detects knock, and viola! p0300

I get this all the time with my '03 at cruise, light throttle, always between 2800-3200 rpm.

https://www.evolutionm.net/forums/ev...tsb-found.html

The patches to turn off the p0300 will work to turn off this "feature" without compromising the knock system in general.

The real answer is to rebuild the transmission, which is something I plan on doing at some point

 

I am getting this on my IX, only it happens at random times, cruise or startup or whatever, and only started after I changed the injectors. I am hoping I can pinpoint what is causing it soon, it is really annoying.

 

No I haven't rebuilt the transmission.

Does your car run really lean (18-19.5 range) and shudder a bit when you trip the code? I just think if it was due to knock detection, it wouldn't run lean. It would go rich as a protection mechanism. I will look for that patch and give it a shot. Not sure if that was in the updated ROM i tried.

 

I had the same problem, same car, only did it at cruise. The P0300 and 18+ AFR is the clue; that stumble is fuel cut.

Mine happened multiple times on the way to VIR, then zero times on track; no problems until I drove home.

Mine is gone since I patched the ROM to eliminate P0300 testing. Not a problem since. It must be driveline harmonics.

 

Thanks! I will have to do a search for that patch!

 

Lol multiple links to the thread on how to disable the P0300 have been posted in this thread already.

 

Sorry to revive a pretty old thread.
I have the exact same problem, where it randomly goes lean and stumbles, but I do not get any CEL codes. I've been running Tephra Mod V7 with 880cc injectors for a long time and this issue just recently started. At first I thought it was a boost leak that I found. Fixed it and the issue returned anyway. I don't thing its the PO300 issue, since I don't get a CEL.

Any ideas?
Thanks!

JCG

 

When I updated my ROM with the patch to disable P0300 testing it went away. It was my driveline harmonics as well.

 

Bump...

Having same issue at 80mph at 3k rpm.

I am also having the issue in second gear, still around 3 or 4k.

I will disable the 0300 code and see if it helps.

 

sounds like the car is going into overun fuel cut while you are cruising. what happens is that at a certain tps and load the car is supposed to shut off the injectors. eg. when decelerating and engine braking. what it sounds like that is happening is that either your tps is calibrated wrong and that 4 or 5% throttle you shud be getting while cruising is being seen by the ecu as maybe 1 or 2% and envoking the overun fuel cut. or maybe your overun fuel cut settings need reconfiguring.

solution? either recalibrate the tps , replace if faulty or reconfig the overun trigger point.

 

Actually disabling the misfire code fixed the issue. Weird right? Yea thats what i said lol.