as it says i went to clear my codes today which is usually just catylist efficency and the occasional boost cut from when it gets to cold down here and a p0300 code was on there. I thought this was only a problem with the 03 evos? any ideas why. is the utec messing with something in my stock ecu.

any ideas would be great.

chris

 

i got a couple p0300s on my '05 in the first week of having my utec. i cleared them and haven't run into the problem since. i'm not TOO worried, but i have been keeping a watchful eye.

 

Its entirely possible the transition between closed loop ECU and the UTEC timing caused it, especially if you have a reflashed ECU, but even if there's just a timing or fueling jump at that transition it can cause a "Knock" that can be seen as a random misfire to the ECU.

After you reset the ECU and drive it for awhile, the ECU relearns the signals it gets and problems tend to resolve themselves.

If you keep getting it, make sure the car is in MAP0 and drive the car like that for awhile.. If it keeps coming back, then it may not be the UTEC.


Although the UTEC doesn't directly mess with anything in the ECU, it does intercept and regenerate most of the signals that go through it. It does a good job of it (otherwise you'd get CEL's all the time) but occasionally if you start the car "too quickly" before the UTEC completely initializes, or have to reset the ECU and don't get the opportunity to put any miles on the car and then load up the car a bit (a dyno run, or a hard drive) you can trigger CEL's too (I think that would happen even on a stock ECU car without the UTEC)

The key is to keep an eye on it, and see if it keeps happening, if it happens one or twice, then never again, I wouldn't worry about it.. If it happens often, or can be reproduced fairly regularly, then I would look at the map your running in the car, or just closely analyze the UTEC's logs, Maps, Parameters, and possibly the wiring harness.

I do know that my car gets the catalyst error more often with the UTEC installed than with the UTEC removed, but that is simply because of the difference in the boost curve with the UTEC and the ECU.

 

thanks it has happened 3 times in the last week all on the same map. i have been running the utec now for over a month and it just started. i am going to put it back to map 0 and see what happens. thanks for your replys.

chris

 

What kind of plugs are you using?

 

still stock

 

Why not just get the P0300 reflash from Mitsu? I'm sure the 03 to 04 ecu's aren't that much different. Plus the day after I installed my utec I went in for the reflash just because I was dynoflashed and just wanted to start off on the base maps and go from there. I never had the code pop up but just to be safe than sorry, plus they bought the story because of the cams.

 

because my car is quite modified and i dont feel like taking everything off. also from what i understand the 04 had the reflash from factory so i dont think it would help.

 

Your probably right, However I think I recall reading a thread from Dynoflash saying the extracted base code (where they build their reflashes from) was indeed different in the 04 than the 03.. but I could be wrong since I can't find the thread anywhere to verify it.

 

well i ordered new plugs, and larger injectors today and will be having the car retuned with the map sensor in on saturday. the car has been maxing out the injectors and i am thinking maybe it is just thought it was misfiring. i have not taken the car over 4k rpms in the last few days and my boost controller has remained shut and i have not got the code back. so hopfully the ecu was wrong with its indication.

 

ok so i put in the injectors today they were fic 750 and i scaled them at 650. I also put in new irridum plugs. car seems to be running great. open loop fueling is on and closed loop boost until i get the map sensor in. but the car is now throwing p0300 codes all the time. I am really lost here tthe car soesnt seem to be misfiring but i have no idea. anybody with suggestions.

 

It may have to do with the built in algorithms in the UTEC. Have you called them about the problem. The PO300 typically is caused by the engine management system's inability to keep up with or be slow enough with values that the stock ECU wants to see to be happy.

I am also dealing with this problem with my system, the ECU+. The guy who created the system has been reworking algorithms left and right trying to keep the ECU happy. So the ECU is somewhat happy, setting off codes only when cruising at a fixed rpm for awhile.

Anyway, when is the CEL coming on? Under what conditions?

 

FWIW the UTEC functions differently than the ECU+ and Xede where they alter the CAS output, the UTEC regenerates it only when you have the cells set to ECU, when the UTEC is controlling timing, it passes the actual CAS signal data to the ECU and UTEC controls its timing directly. Its possible its a result of a sudden fueling or timing change causing the type of conditions that the ECU might detect as a random misfire, or possibly the transition between the ECU and passthrough (35% TPS) and the difference in the values.

Since I have Never gotten a P0300 code, I think there's is some predisposition or sensitivity to it on a car already before installing the UTEC that is amplified when you add a piggyback system.

 

I wasn't aware of the UTEC's exact function as far as interpreting the cam and crank angle sensors. I think what you said is true about an engine management possibly causing the knock just a tad more than on a stock running car but, just enough to make the ECU unhappy.

I know Tom (ECU+) has been working on trying to solve this problem for awhile as he has sent me numerous firmwares to test out. He has almost narrowed the problem down. In that case it is in the algorithms that the ECU+ sends to the ECU.

 

ok i lowered the tps to 30% because the little hickup that was happening when it swaitches over to open loop fueling was pretty bad. That made it a little easier transition and so far no codes. Other then that im not sure what to do .The car seems to be running fine however if i come off the gas at a high rmp it makes a stuttering sound as the rpms fall?