idle control behaviour
Posted: Fri Jul 27, 2018 8:14 pm
With the weather being very hot recently, i thought i would have a play with improving the idle control to compensate for having the Air Con switched on and higher than normal ACT which affects idle stability.
I had no idle duty added for when the Air Con is switched on and no ACT based idle duty added. So i added some duty for these to see what effect it would have. This improved the high temperature behaviour for idle.
Having now logged the Throttle Bypass Valve duty and the various idle parameters, its not doing what i expected.
When driving at normal speeds the TBV duty is not sat at the bypass duty in run mode value (5%), it follows the open loop idle control settings, so if i have 5% more duty added for AC switched on and 2% added for ACT higher points for example, the TBV duty sits 7% above the base duty value set in the open loop control.
So without any compensations for Air Con and ACT, whilst driving normally at speed the TBV duty is sat at open loop value of 40%, then add any corrections and you would see 47% in the above example.
Why is this, what is the purpose of the Bypass Duty In Run Mode parameter?
If the TBV duty is varying with compensations, this is going to have an effect on the amount of air being passed through the throttle body, so the load reference of TPS isn't going to be valid or consistent, it's going to vary depending on if the AC is on or off if you are using any ACT compensations for the idle control that will also alter the amount of air flowing compared to your load reference. This can't be a good thing?
Any thoughts on this?
I had no idle duty added for when the Air Con is switched on and no ACT based idle duty added. So i added some duty for these to see what effect it would have. This improved the high temperature behaviour for idle.
Having now logged the Throttle Bypass Valve duty and the various idle parameters, its not doing what i expected.
When driving at normal speeds the TBV duty is not sat at the bypass duty in run mode value (5%), it follows the open loop idle control settings, so if i have 5% more duty added for AC switched on and 2% added for ACT higher points for example, the TBV duty sits 7% above the base duty value set in the open loop control.
So without any compensations for Air Con and ACT, whilst driving normally at speed the TBV duty is sat at open loop value of 40%, then add any corrections and you would see 47% in the above example.
Why is this, what is the purpose of the Bypass Duty In Run Mode parameter?
If the TBV duty is varying with compensations, this is going to have an effect on the amount of air being passed through the throttle body, so the load reference of TPS isn't going to be valid or consistent, it's going to vary depending on if the AC is on or off if you are using any ACT compensations for the idle control that will also alter the amount of air flowing compared to your load reference. This can't be a good thing?
Any thoughts on this?