8D Spark advance help
Thread Starter
Member
Joined: May 2006
Posts: 152
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Car: 1990 Corvette
Engine: 415
Transmission: six speed
Axle/Gears: Dana44 3.73
8D Spark advance help
hi all
i noticed the following thing, when make some testruns...
when the engine is relatively cold, i get some erratic timing numbers...
example
900rpm, 70kpa should be at 28°adv...DM recorded 20.7°adv (35°C)
1800rpm, 40kpa should be at 38.7°adv...DM recorded 23.9°adv (42,5°C)
where does this come from?
when the engine gets warmer, the numbers from TC and DM match...
what is the constant "Base Cool.Adv.Correction table Bias"
if someone is interested, i can post or send my logfiles
thank you
i noticed the following thing, when make some testruns...
when the engine is relatively cold, i get some erratic timing numbers...
example
900rpm, 70kpa should be at 28°adv...DM recorded 20.7°adv (35°C)
1800rpm, 40kpa should be at 38.7°adv...DM recorded 23.9°adv (42,5°C)
where does this come from?
when the engine gets warmer, the numbers from TC and DM match...
what is the constant "Base Cool.Adv.Correction table Bias"
if someone is interested, i can post or send my logfiles
thank you
Joined: Apr 2004
Posts: 3,180
Likes: 3
From: Browns Town
Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: 8D Spark advance help
The cold startup will use the 100 Kpa cell in the main table until warmup.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
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Joined: Apr 2004
Posts: 587
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From: Calif
Car: 75 Vette
Engine: 406 TPI
Transmission: 700 R-4
Axle/Gears: 373
Re: 8D Spark advance help
The cold startup will use the 100 Kpa cell in the main table until warmup.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
How can I find out it coolant comppensation effects idle spark
Thread Starter
Member
Joined: May 2006
Posts: 152
Likes: 0
Car: 1990 Corvette
Engine: 415
Transmission: six speed
Axle/Gears: Dana44 3.73
Re: 8D Spark advance help
The cold startup will use the 100 Kpa cell in the main table until warmup.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
I forget exactly which parameter is the threshold for when to go to the normal cell. You could also be looking at the "closed throttle" table instead of the main for the 900 RPM reading you had.
The cold "bias" is used for the table at 813B->81A6 called "SPARK ADV Temp. Correction Vs. Load Vs. Temp." (In my definition anyway)
If the bias = 20*, then anything in the coolant compensation table with 20* will have no change to the SA in the main table when temperature changes.
If the table has a lower value then the spark would be decreased by the difference between the bias and the main SA table value.
The difference is applied to the main spark table.
I'm not sure if the coolant compensation is used on the closed throttle table.
ok, so, whats cold startup until warmup in numbers of temperature?
that would explain the low SA numbers, as i have about 20°adv at 900rpm and 100kpa...
i looked at Closed TPS SA, but i have higher numbers there, about 30°at 900 idling..
can you explain me the Bias thing with numbers, i´m not really sure about it...
thank you very much
Joined: Apr 2004
Posts: 3,180
Likes: 3
From: Browns Town
Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: 8D Spark advance help
Bias value of 20
Coolant compensation table "cell" = 20
There would be no change to the SA in the "main" spark table.
Bias = 20
Coolant table cell = 18
2 degrees would be removed from the value in the main spark table when at that temp.
Inverse would also be true,
Bias = 20
Coolant table cell = 22
2 degrees would be added to the value in the main spark table.
HTH
----------
research the actual sequence of events in the code. Only way unless someone that has already done the work can answer.
Coolant compensation table "cell" = 20
There would be no change to the SA in the "main" spark table.
Bias = 20
Coolant table cell = 18
2 degrees would be removed from the value in the main spark table when at that temp.
Inverse would also be true,
Bias = 20
Coolant table cell = 22
2 degrees would be added to the value in the main spark table.
HTH
----------
research the actual sequence of events in the code. Only way unless someone that has already done the work can answer.
Last edited by JP86SS; Oct 9, 2007 at 11:09 AM. Reason: Automerged Doublepost
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