MoTeC Global Forum

Hi All,

im trying to find out what are the best way to make the idle control best.
My daily driver is a 5 cylinder Audi with M600.It has a 2 wire BOSCH PWM idle valve.
Getting proper idle is not a problem,with "constant" electrical load,i just need to set the Normal Position to a good value.
But when this load changes to anothe constant load(wiper,headlights,heater,colant fan on),the rpm drops,and the PID cannot keep up with the increased air/RPM need.From the logs its clear that the ECU tries to increase the duty,but its slow,and not sufficient.I just want to refine it.

With more P I or D it just begins to be unstable.

Any help appriciated.

Thank you,
Peter

My Battery voltage is not constant,with full electrical load it drops to 12V,which is not ideal for sure.But that gave me the idea to rescale the Idle Normal Position Table from AT/ET to BATTV/ET.This simplifies the work of the PID,since different Normal Position are there for different e-loads.

Is the voltage drop that causes the unwanted behaviour?

Peter

do u have the correct inj batt comp values in, if battery volatage drops it could run lean, then the idle control wont recover it,

I think you have to increase air flow through the butterfly so that with engine hot and no load on it is just below the desired idle speed. Have the idle control valve do as little as possible there to keep it from working to hard (big fluctuations in DC) to have the idle stable. This will allow you to clamp the allowable DC to make it more stable


Maybe worth a try?

If you watch the log you can see that lambda is steady no matter what the Vbatt is.And there is also the lambda trim...

andi m wrote:do u have the correct inj batt comp values in, if battery volatage drops it could run lean, then the idle control wont recover it,

Sure,thanks for the idea.With less advanced ecus this is the way i do it every time...

Martin wrote:I think you have to increase air flow through the butterfly so that with engine hot and no load on it is just below the desired idle speed. Have the idle control valve do as little as possible there to keep it from working to hard (big fluctuations in DC) to have the idle stable. This will allow you to clamp the allowable DC to make it more stable


Maybe worth a try?