97' Spark Question-Power High vs Low tables
01-27-2008, 10:52 AM
#1
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97' Spark Question-Power High vs Low tables The 97-98 have pretty aggressive spark tables, and I have a unique situation. I have a car that is making TOO MUCH power. Dyno time is limited, and I'm thinking of running it with the Low Octane tables and seeing how much power I lose. I've made 3 sets of tables (high, low, and 2 sets in between) in order to shave offer 10-15hp.
Anybody have a clue how much power you lose running in low-octane mode?????
Thanks!
Anybody have a clue how much power you lose running in low-octane mode?????
Thanks!
01-28-2008, 02:34 PM
#3
Why not just run a road runner ecm hardware? Then you can just make the changes instantly.
If you need to limit the power, why not just dump in the restrictor plate to regulate it.
"A Low octane mode" is non exsistant. It does not exsist. The ecm does use the high and low octane tables but it uses a percentage system. Meaning that when no knock is detected, the ecm will use 100% of the high octane table. If some knock is detected then it just starts to pull a percentage of the high vs low table. For example, if the value is 30 in the high octane and 10 in the low, If the ecm commands a 50% state, then the value used may be 20 degree applied. But if no knock is detected for a few more events, then the ecm will start to put it back in. You can log this in Pids in the scan too. The only time it would be FULLY the low octane table is if there is a MAF system failure or you have REALLY misserable gas quality.
If you need to be lower than a set value, i would suggest setting up your coolant temp sensor spark modifier to pull timing based on a set resistance, When you flip a switch with a resistor on it, it will use different timing amount. Then when the switch is off, it will go back to normal.
If you need to limit the power, why not just dump in the restrictor plate to regulate it.
"A Low octane mode" is non exsistant. It does not exsist. The ecm does use the high and low octane tables but it uses a percentage system. Meaning that when no knock is detected, the ecm will use 100% of the high octane table. If some knock is detected then it just starts to pull a percentage of the high vs low table. For example, if the value is 30 in the high octane and 10 in the low, If the ecm commands a 50% state, then the value used may be 20 degree applied. But if no knock is detected for a few more events, then the ecm will start to put it back in. You can log this in Pids in the scan too. The only time it would be FULLY the low octane table is if there is a MAF system failure or you have REALLY misserable gas quality.
If you need to be lower than a set value, i would suggest setting up your coolant temp sensor spark modifier to pull timing based on a set resistance, When you flip a switch with a resistor on it, it will use different timing amount. Then when the switch is off, it will go back to normal.
01-28-2008, 05:29 PM
#4
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I wasn't clear, I've transfered the Low Octane table into the High Octane table. Or in other words, I've cut the 97's rather high OEM spark advance (29) down to around 20.
I only need to trim around 10hp. Will cutting 9deg of timing take this much power away. I do have a box full of restrictor plates, but it's much quicker to do software changes only when your paying $150/hr at the dyno shop.
I only need to trim around 10hp. Will cutting 9deg of timing take this much power away. I do have a box full of restrictor plates, but it's much quicker to do software changes only when your paying $150/hr at the dyno shop.