Hello fellow EvoM-ers,

I need some advice. My 2006 Evo IX MR has been throwing P0300 codes more and more frequently over the past few months and I have been unable to determine the cause.

I've taken the car into 2 different dealers and 1 performance shop over the past 6 months, without success. I've tried everything I can think of (new spark plugs, new spark plug cables, compression check, boost check, MAF sensor, etc.), but the problem persists.

Typically, the code is thrown during idling, after the car starts up. But also it sometimes is thrown during highway driving. What's baffling about the code is that I don't feel any knocks or reduction in power at all. THE CAR FEELS AND PERFORMS AS USUAL!

Here are the mods I have on the car for your reference:
- Vishnu DP, High-flow cat, CBE
- K&N drop in filter
- Grounding kit
- Vishnu custom ECU flash
- Exedy Twin Plate HD clutch
- Megan Coilovers

I have three potential culprits that I have not been able to eliminate yet, and I need your help to figure out which one is the most likely:
- Clutch noise -- Could my recently upgraded clutch (stock -> Exedy HD) being making enough noise to throw the knock sensor?
- Injectors/Fuel Pump -- Could my injectors or fuel pump be failing? How likely is this and how could I determine if this were the case?
- ECU -- Could there be corrupted data in my ECU that would be fixed by a reflash? Has anyone experienced this before?

Where should I go from here?

EDIT: By the way, I've also tried contacting Vishnu and they were absolutely useless. Now they won't even respond to my emails. *grrr*

 

Tuesday bump!

 

No suggestions? Really?

 

are you tuned to throw the code when knock is detected?


Edit: You could also check for a vacuum leak
Edit2: I don't know much about grounding kits; I wonder if a bad/ill-installed one could cause issues with your spark cycle.

 

I have the same car, coilovers, clutch. Get the same code now and then too. Check on evom for a patch to just disable that particular code.

 

not sure what's causing it but if you aren't feeling any effects from the code then maybe it would be easier to simply disable it with a new tune. some things just aren't worth chasing by throwing parts and money at them.

 

Yes, the tune doesn't modify any error code handling/detection/throwing.

I actually just got off the phone with Vishnu and they suggested sending my ECU in to be "re-flashed". Not sure how that will help but it's worth a shot. I'm also going to take the car into Protech Performance here in Austin to see if they can find a boost leak (this will be my 4th shop and probably 12th visit to figure this out :-/)

Thanks for the input guys! If you have any other ideas I'd love to hear 'em!

 

The only way that's going to help is if they put in a different tune to disable the code or address the idle settings to smooth it out a bit better.

 

what trips the p0300?

 

most commonly cams loping causes the ecu to think there's a misfire. some cars never have a problem, for others it comes and goes and yet others have it constantly.

 

Yeah, I have s2's.

I am petrified about throwing a p0300 next month when i have to have my emissions done by the end of august. I run a full hta3076r head-back exhaust w/ open divorced wastegate dump too! don't want the car to fail for p0300 and them to think ... hmmm whats that smell at idle?

 

thank god i live in missouri... all we have to do for inspections is make sure all the lights work and its got a cat, which i dont so you learn to find the inspectors that dont care.. my car throws the po300 every second it possibly can, lol. i have 280 comp cams so i know thats my problem

 

My original Evo threw the P0300 all the time thanks to drive line noise. We replaced every possible thing (MAF, FP, FPR, ECU, Turbo, Plugs, coils, wires, Cam and crank position sensors, knock sensor etc..). It ended up being the trans making enough noise the ECU pulled timing.

 

what rom are you running? i had the same issue after a clutch install. all it turned out to be was driveline noise confusing the knock sensor.

check this out...
https://www.evolutionm.net/forums/ev...-cruising.html

 

Thanks for the tips! I'll try them and let you know if I can fix the issues.

Does anyone know if the P0300 code causes the ECU to pull boost in addition to pulling timing? i just noticed that my boost is peaking at ~15psi?!?! (I had the shop check for a boost leak, and I'm all good btw).