Alrighty ... I've been working with a 2.3l GT30 VIII for a while and helping tune it remotely. However, we've been hitting the same issue for a while now ... a P300 that will not go away. the code seems to pop up in the lower load ranges ... 30% to 80% and below 3500 RPM.

This is the car ... the important bits anyway.

Evo VIII
2.3l
ported/polished head
BC 280 cams (currently +2º/-2º)
GT30R (HAFE I think)
Stock ECU w/ 94170015 ROM rescaled to 340/8000
EGR deleted
HKS Ignition amp
Copper plugs @ .028
950cc injectors
large TB

I've tried everything I can imagine to address the issue. I've tried timing values all over the board ... from +18º to +32º at cruise. I've got all of the defined maps re-scaled to match the load/RPM changes ... this includes the newly found EGR tables (even though the EGR is gone). We've changed plugs at different gaps. He's tried different cam positions (from 0º to +4º on the intake).

I'm at a loss. The tune is great except for the P300 that hits randomly. I'll also note that the freeze fram from ScanTech is odd ... showing stuff like 52% load at 2600 RPM and 86% TPS.

Fuel trims vary, but level out within 2% usually. The car is mostly knock free except for an inconsistent 1-2 count between 2500 and 3100. This seems to be unrelated to the tune as timing changes in this area make no difference and AFR is in check. Could the 2.3 just be a little noisy in this area and cause the P300?

Any help and suggestions are appreciated ... I'm just at a loss for where to go from here. Thanks.

 

The conditions under which p0300 is checked and triggered are not so easy to re-establish. The noise shouldnot be an issue as the evaluation is purely related to monitoring of the crank angle sensor and determining the misfire condition as in the attached page from manual (check conditions, judgement criterion). Try to read them through - maybe something will sound suspicious in your case.

 

TB arent you one of the ECUflash Gods?(From what I heard).......

 

what is that supposed to mean?

 

has the transmission been cracked open on this car? I am curious if the 5th gear syncros have been replaced or not. I know there is a TSB out for this problem.

I have similar issues with mine. light load, just under 3500 rpm, bam... p0300...

 

IDK

 

Lol ... I'm active in the forum here is that's what you mean. I'd like to think I'm good at what I do, but I wouldn't go so far as to use the term "god." I've contributed very little in comparison to what others here in the forum have. I am also not beyond asking for input from my peers to help solve a problem.

There are really only so many things that can cause a misfire and the P300 is technically a misfire code, but as mentioned the P300 isn't always caused by a misfire. I feel like we've checked most of the known causes to no avail ...

 

I have a similar problem on mine but it only started after going with the bigger injectors on a stock bottom end. Cams had been replaced and no issues. Big injectors, issues. I was able to make it happen a great deal less with some changes to the latencies but it still hasn't gone away completely. I remember reading somewhere on here that the resonance in the engine at the that rpm range during light throttle cruise is somewhat unusual. My car runs great and is very strong. I just deal with it.

Josh

 

None of the triggers listed seem to apply unless the CA sensor is going out. The EGR deletion would be the second possible culprit, but I don't know if others have had the issue. Currently, the EGR is taken care of using the check disable referenced in the JDM MAP install. Perhaps this method of disabling the EGR doesn't stop the P300 when the entire EGR system is removed.

 

The trans has been repaired using both p0300 TSB's for the input bearings, sychro's, and the reverse idler gear.

ScanTech freeze frame also notes that the Intake Temp is 32-36 degrees F, where in actualality it has been 76-110 degrees F (this issue has been going on since begining of the summer until now)

 

the EGR is disabled by unpluging the valve and pluging the vac ports.

 

That sparks an idea ... have you tried just leaving the plug attached to the solenoid but leaving the ports plugged? I would think there would be a different code for a missing EGR solenoid, but I'm not certain. I thought you'd removed the solenoid.

 

I had both p0300 TSB's for the trans done and it still kept coming on for me. They finally replaced the trans and the problem went away.

 

already fought with the Mitsu DPSM about the transmission. and so SOL with it. The car didnt have the P0300 until after the stroker and gt30.

I will check, I believe im mistaken. the solenoid is pluged in but the plastic nipples are broken. (use to be unpluged, but after 1 of the rounds of diag we agreed to replug in.)

 

Okay ... lol, we've tried so many things I'd forgotten that.