Resetting ECU
Thread Starter
Newbie
Joined: Apr 2005
Posts: 65
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From: Redding, CA
Resetting ECU
If you put 100 octane gas in your car should you reset the ECU by unplugging Ground from the battery for 15 minutes? I have searched and it looks like some people have asked but no answers. I've read that some ECU's will learn on the fly and there is no reason to reset them, Is that true with ours?
Is there any reason to ever reset the ECU?
Is there any reason to ever reset the ECU?
Newbie
Joined: Sep 2005
Posts: 6
Likes: 0
From: Indianapolis, IN
if the evo ecu is anything like the dsm ecu, there's some type of "octane memory." that's why keydiver chips and dsmlink have octane reset options on key on. i think i it has something to do with a knock sum memory. if your car knocks consistently, the ecu may attribute it to the fuel and permanently pull timing as a safety precaution. not really sure how it works, though.
So, if you think that for some reason your ecu is "permanently" pulling timing due to the state of your tune on pump, it might be advantageous to reset the ecu in order to get full timing on the race fuel. Personally, I don't ever reset the ECU when evacuate the pump fuel and throw in race fuel.
Actually, here's a good explanation from the keydiver ships site.
What is the "octane value"?
The "octane value" is a term coined by Todd Day to refer to the memory address that is used as a longterm timing trim. If the ECU hears a moderate amount of knock for a long time, or alot of knock for a shorter amount of time, it will keep reducing the value in this memory address. Normally set at 255 (FULL), it will keep getting reduced as long as it hears knock. This could be due to just getting a bad tank of gas, or perhaps running more boost than you are tuned for. But, even if you fix the problem, by filling back up with good premium fuel, or turning down the boost, the "octane value" can take several hundred miles to work its way back up to "FULL" value again. This feature of my chips resets the "octane value" to "FULL" everytime you start the car! However, just as a warning, since you are removing this safegaurd that the ECU uses to protect your engine, it is YOUR responsibility to monitor your knock sum!
So, if you think that for some reason your ecu is "permanently" pulling timing due to the state of your tune on pump, it might be advantageous to reset the ecu in order to get full timing on the race fuel. Personally, I don't ever reset the ECU when evacuate the pump fuel and throw in race fuel.
Actually, here's a good explanation from the keydiver ships site.
What is the "octane value"?
The "octane value" is a term coined by Todd Day to refer to the memory address that is used as a longterm timing trim. If the ECU hears a moderate amount of knock for a long time, or alot of knock for a shorter amount of time, it will keep reducing the value in this memory address. Normally set at 255 (FULL), it will keep getting reduced as long as it hears knock. This could be due to just getting a bad tank of gas, or perhaps running more boost than you are tuned for. But, even if you fix the problem, by filling back up with good premium fuel, or turning down the boost, the "octane value" can take several hundred miles to work its way back up to "FULL" value again. This feature of my chips resets the "octane value" to "FULL" everytime you start the car! However, just as a warning, since you are removing this safegaurd that the ECU uses to protect your engine, it is YOUR responsibility to monitor your knock sum!
