C5 TPS & Base Idle Spark
07-13-2015, 03:20 PM
#1
C5 TPS & Base Idle Spark
I have posited this in a tuner software/hardware forum but maybe someone here will be able to clarify this.
The TPS on my Z06 never reads less than 8-9%. In order for the Base Idle Spark Tables to be used, a closed throttle condition is required. That condition is defined as 1.19% or less.
I have logged my spark advance at idle and the actual spark is not related to the Base Idle Table. It is in fact being derived from the High Octane Spark Table.
So the conventional wisdom of creating a backstop for an idle condition that drops through desired idle and stalls or bounces around before settling down by increasing the spark values in the Base Idle Table does nothing.
So it looks like a C5 modified with a cam or heads that does not drop to idle and land softly must be addresses with Desired Airflow, Throttle Cracker, and High Octane Spark, assuming VE and MAF are in the ball park.
I suppose another option might be to change the closed throttle condition from 1.19% to something just above actual TPS idle values to activate Base Spark.
I have looked at the GM Service Manual and it indicates the idle TPS should be from 3% to 10%.
I know there are folks that delve in to this way deeper than I ever have, so can anyone elucidate?
The TPS on my Z06 never reads less than 8-9%. In order for the Base Idle Spark Tables to be used, a closed throttle condition is required. That condition is defined as 1.19% or less.
I have logged my spark advance at idle and the actual spark is not related to the Base Idle Table. It is in fact being derived from the High Octane Spark Table.
So the conventional wisdom of creating a backstop for an idle condition that drops through desired idle and stalls or bounces around before settling down by increasing the spark values in the Base Idle Table does nothing.
So it looks like a C5 modified with a cam or heads that does not drop to idle and land softly must be addresses with Desired Airflow, Throttle Cracker, and High Octane Spark, assuming VE and MAF are in the ball park.
I suppose another option might be to change the closed throttle condition from 1.19% to something just above actual TPS idle values to activate Base Spark.
I have looked at the GM Service Manual and it indicates the idle TPS should be from 3% to 10%.
I know there are folks that delve in to this way deeper than I ever have, so can anyone elucidate?
07-13-2015, 03:29 PM
#2
Le Mans Master
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I have posited this in a tuner software/hardware forum but maybe someone here will be able to clarify this.
The TPS on my Z06 never reads less than 8-9%. In order for the Base Idle Spark Tables to be used, a closed throttle condition is required. That condition is defined as 1.19% or less.
I have logged my spark advance at idle and the actual spark is not related to the Base Idle Table. It is in fact being derived from the High Octane Spark Table.
So the conventional wisdom of creating a backstop for an idle condition that drops through desired idle and stalls or bounces around before settling down by increasing the spark values in the Base Idle Table does nothing.
So it looks like a C5 modified with a cam or heads that does not drop to idle and land softly must be addresses with Desired Airflow, Throttle Cracker, and High Octane Spark, assuming VE and MAF are in the ball park.
I suppose another option might be to change the closed throttle condition from 1.19% to something just above actual TPS idle values to activate Base Spark.
I have looked at the GM Service Manual and it indicates the idle TPS should be from 3% to 10%.
I know there are folks that delve in to this way deeper than I ever have, so can anyone elucidate?
The TPS on my Z06 never reads less than 8-9%. In order for the Base Idle Spark Tables to be used, a closed throttle condition is required. That condition is defined as 1.19% or less.
I have logged my spark advance at idle and the actual spark is not related to the Base Idle Table. It is in fact being derived from the High Octane Spark Table.
So the conventional wisdom of creating a backstop for an idle condition that drops through desired idle and stalls or bounces around before settling down by increasing the spark values in the Base Idle Table does nothing.
So it looks like a C5 modified with a cam or heads that does not drop to idle and land softly must be addresses with Desired Airflow, Throttle Cracker, and High Octane Spark, assuming VE and MAF are in the ball park.
I suppose another option might be to change the closed throttle condition from 1.19% to something just above actual TPS idle values to activate Base Spark.
I have looked at the GM Service Manual and it indicates the idle TPS should be from 3% to 10%.
I know there are folks that delve in to this way deeper than I ever have, so can anyone elucidate?
Ed M
07-13-2015, 09:38 PM
#3
Thanks Ed.
Conventional wisdom stands and I should be dropping into the Base Spark Table.
Absolute Throttle Position is not equal to Base Spark Closed Throttle Threshold. The Excel doc converts Absolute Throttle Position to a Base Spark Closed Throttle Threshold value.
Conventional wisdom stands and I should be dropping into the Base Spark Table.
Absolute Throttle Position is not equal to Base Spark Closed Throttle Threshold. The Excel doc converts Absolute Throttle Position to a Base Spark Closed Throttle Threshold value.
07-14-2015, 01:14 AM
#4
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St. Jude Donor '13-'14-'15
Most all Drive by wire T-Bodies do NOT go to "0" at idle when reading the TPS with a scanner----Same goes for WOT--Most only show like 87% at WOT----I don't know if this is a scanner issue or not--But I have never had to raise the minimum TPS setting in a tune even with a racidically modded engine-- A drive bt wire engine also does not have an idle air control valve so the throttle is always somewhat open If you take off the air intake and look at the throttle blade even with the key OFF the blade comes to rest slightly opened---
