LS1 Cylinder Charge temp bias question
07-09-2008, 10:02 PM
#1
LS1 Cylinder Charge temp bias question The Cylinder Charge Temp. Bias stock table uses the IAT and ECT sensors for its calcs. and relys on the IAT about 90* and the ECT about 10*.
I have read about setting the bias to 1.00 for the whole table so that it uses the IAT and ECT equally and you only had to re-tune the VE table and all other tables would not change, and when I did this I have numbers over 100 in the VE table on a NA engine....is this correct?
I have seen a couple of the heavy hitters personal files and noticed this done but it has been over a year and I know somethimes things and ideas change...so is this still considered to be correct tuning stratagy?
Thanks for any help!
I have read about setting the bias to 1.00 for the whole table so that it uses the IAT and ECT equally and you only had to re-tune the VE table and all other tables would not change, and when I did this I have numbers over 100 in the VE table on a NA engine....is this correct?
I have seen a couple of the heavy hitters personal files and noticed this done but it has been over a year and I know somethimes things and ideas change...so is this still considered to be correct tuning stratagy?
Thanks for any help!
07-10-2008, 12:10 AM
#2
I think this is what you are talking about?
I am not sure about the effect of IAT on final AFR. I think it can be a fudge factor. I tried to mathematically calc the difference in kgs per diferent temps and then apply it to our engines model in efi live cos5. I loaded that into cos5 with this stock table and it was too much of an affect on everything. if this factor table was correct then that shouldn't of happened.
I get the basic theory but i am not sure if how it is calibrated fom the factory is really only what is stated in that caption there may be something else to it.
The PCM calculates the charge temperature (in degrees Kelvin) using the following formula
273.15+IAT+((ECT-IAT)*factor) where factor is obtained from this calibration.
At low airflow "factor" is closer to 1 which weights the charge temperature in favour of ECT.
At high airflow (>150g/s) "factor" is closer to 0 which weights the charge temperature in favour of IAT.
The theory being that heat (ECT) is transferred from the heads and manifold after the IAT has been measured and prior to the air entering the cylinder
273.15+IAT+((ECT-IAT)*factor) where factor is obtained from this calibration.
At low airflow "factor" is closer to 1 which weights the charge temperature in favour of ECT.
At high airflow (>150g/s) "factor" is closer to 0 which weights the charge temperature in favour of IAT.
The theory being that heat (ECT) is transferred from the heads and manifold after the IAT has been measured and prior to the air entering the cylinder
I am not sure about the effect of IAT on final AFR. I think it can be a fudge factor. I tried to mathematically calc the difference in kgs per diferent temps and then apply it to our engines model in efi live cos5. I loaded that into cos5 with this stock table and it was too much of an affect on everything. if this factor table was correct then that shouldn't of happened.
I get the basic theory but i am not sure if how it is calibrated fom the factory is really only what is stated in that caption there may be something else to it.
Last edited by 2002_Z28_Six_Speed; 07-10-2008 at 12:19 AM.
07-10-2008, 08:52 AM
#3
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Part of the problem is that the IAT sensor gets heat soaked. I moved the sensor to a location low in front of the radiator. This helped alot.
