ISC duty cycle

[CJK440]

As I understand it ISC duty cycle is proportional to the position of the pintle inside the valve. Correct?

I have seen various ranges recommended but is there an ideal ISC duty cycle that one wants to achieve at a hot idle? I would imagine it would be the duty cycle value that correlates to the pintle position with the ISC unplugged (given the idle screw adjustment procedure with the ISC unplugged).

 

[oxfordgt]

You want your DC to .15-.25 and the integrator to .00 at operating temp idle.

 

[CJK440]

You want your DC to .15-.25 and the integrator to .00 at operating temp idle.

.15? iirc .15 is the minimum which means if its at .15 it can only compensate in one direction (allowing more air bypass).

 

[decipha]

correct, thats the most ideal position for it to be

 

[Black02GT]

You want your DC to .15-.25 and the integrator to .00 at operating temp idle.

I agree with this, I aim for .20. I follow the technique provided by I believe Eric Brooks. Set the ISC Duty Table to all .20, turn all adaptive controls off, set your target RPM. Start the car, adjust the idle screw until it idles at the target, then reset the ISC Duty table and turn the adaptive on. That should get you where you want to be. I tried using other techniques like using the idle air integrator and changing the ISC to minimize that but the previous method was the easiest for me and my tricky Dragon TB.

 

[CJK440]

I adjusted the throttle stop screw per Ford Racing procedure. Adjust screw to get desired rpm with ISC unplugged, then adjust tps and clear KAM. It appears my ISC duty cycle wont go below .327026. That the min value for multiple datalogs. Hot idle is 50 rpm more than commanded and when it idles above commanded the ISC duty cycle is a dead steady .327026. To further confirm, I gave it more screw and just idles even higher with the ISC duty cycle at the same dead steady .327026. It appears its at its limit.

Perhaps the result of using a 03/04 Cobra ISC with an 04 GT ECU??

 

[oxfordgt]

What is your integrator reading at temp?

I don't like that method of unplugging the ISC since it could be open at the moment you unplug it. I set the idle screw with the car running and isc plugged in. Adjust the screw to get the commanded idle then datalog isc integrator and adjust it to get the integrator to .00. If you can't get the duty cycle down you probably need more timing at idle.

 

[CJK440]

What is your integrator reading at temp?

I don't like that method of unplugging the ISC since it could be open at the moment you unplug it. I set the idle screw with the car running and isc plugged in. Adjust the screw to get the commanded idle then datalog isc integrator and adjust it to get the integrator to .00. If you can't get the duty cycle down you probably need more timing at idle.

So with the ISC duty cycle flatlined at .327026, my integrator is flat lined at 0.0000. Something seems wrong.


Timing at idle is only 8.5. Sounds low.

 

[oxfordgt]

Yeah that's very low. I have very large cams so mine will be higher than most but my idle cold runs 32* and 24* once warm. You should be anywhere from 12*-20* if you have a mild cam. What is your borderline knock table say at idle loads? What retards for act and ect do you have set?

 

[CJK440]

Yeah that's very low. I have very large cams so mine will be higher than most but my idle cold runs 32* and 24* once warm. You should be anywhere from 12*-20* if you have a mild cam. What is your borderline knock table say at idle loads? What retards for act and ect do you have set?

BSK shows 21 degrees advance at .200 load / 900 rpm and I logged .205 load / 880 RPM.

Retard for etc and act is...



And I had a 204 ect and 130 act after a long idle in my garage (180 degree stat). Both modifiers were 0 for load .421 rpm 1216 and below.. So its pulling some hefty timing.

What are good low and high fan settings for 180 stat???? Fan low on is 200 and high on is 210.....

 

[oxfordgt]

I have mine at 194 and 206

 

[CJK440]

Dropped the fan settings and it stays around 190 with a 180 stat.

I also loaded the ISC transfer table and normalizers from an 03/04 Cobra since that is the valve I am using. Big difference in the settings between the two. I assume this is the table I set to all a single number (.20 etc) in order to lock the ISC in that spot?

 

[oxfordgt]

I don't know, never had a reason to lock the ISC duty cycle