high octane/ low octan.e tables
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From: Lake Tapps, WA
high octane/ low octan.e tables How does the PCM decide which table it's using? Is it by knock? Also on hptuners is there a method or device to make sure your running the high octane tables?
Thanks this is all new to me
Thanks this is all new to me
In most LS1 applications you can log the knock learn factor to see if you are using the high or low octane table, our help file has a nice description of how the high/low tables work.
You should only do this if you're tuning the VE tables (and thus have the MAF failed), and copy them back when you're done. If you're just copying them and leaving them, thats very irresponsible in the tune as it's not leaving the PCM any choice when something does go wrong.
Thread Starter
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From: Lake Tapps, WA
So I would only be using the low octane table if I had a failure, certain codes and knock? If you where running on the low table would the pcm automatically switch to high octane if the failure or condition changed?
Staging Lane
Joined: Aug 2006
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From: Calgary
You should only do this if you're tuning the VE tables (and thus have the MAF failed), and copy them back when you're done. If you're just copying them and leaving them, thats very irresponsible in the tune as it's not leaving the PCM any choice when something does go wrong.
Knock retard pulls timing for a set time, and then gives it back, and with bad gas, that will result in knock again and again and again...with proper functioning low octane tables, when the car knocks enough, the PCM will give up and run solely off the low octane tables until you fill the tank...then it will try again...knock retard can't function until it see's knock...so it has to let it come back and knock...what would you rather have your engine do?
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TECH Enthusiast
Joined: Nov 2006
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From: Katherine N.T Australia
Think of the initial detection of knock in the same way as STFT's. They'll fix it for the moment but wont remember for later. Then think of Adaptive Spark (The blend between high and low spark tables) as LTFT's.. That's about as simple a description as I can think of off hand.
If you don't know how fuel trims work, that description probably wont help you.
If you don't know how fuel trims work, that description probably wont help you.
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