DTAForum.com - a forum for the DTA ECU

Hi to everyone!

If i set all values in the base idle PWM table to 100 it has the same effect when i test the idle valve so will keep the valve fully open?

It's a Marelli 2 pin idle valve used in Cosworths and Fiats, by default it is closed.

If closed loop is off, then yes.

I can achive a good cold start if i directly open the iscv using a regular 2 pole switch.(100 pwm somehow does not open the valve fully).
Can i wire in a switched earth to the wire going from pin 9 to iscv? so i could overwrite the ecu during cold start?

There is also a max valve % setting, make sure this is set at 100 also

gigford wrote:I can achive a good cold start if i directly open the iscv using a regular 2 pole switch.(100 pwm somehow does not open the valve fully).
Can i wire in a switched earth to the wire going from pin 9 to iscv? so i could overwrite the ecu during cold start?

I'm speculating here but isn't a 100% PWM duty going to provide a 50% opening? It is a solenoid / mechanical device that is required to open / close at anything between 20 - 60hz? and with best will in the world these are 'clunky' mech, devices that just don't match their expectations. Hence when switched, they can achieve 100% opening.
If the OP can only achieve a good start with an 'actual' 100% open IAV, may I suggest adjusting the throttle stop screw to just crack the throttle blades and then trim down the IAV duty cycle to control the idle airflow?

100% PWM IS fully ON.

If whatever device is not functioning fully when you think it is 100%...then it probably isnt 100%. Test with a meter for duty cycle or on a scope.

katana wrote:I'm speculating here but isn't a 100% PWM duty going to provide a 50% opening?

No. 100% duty cycle should open the idle valve fully. If it's not fully open with 100% duty cycle, then the device is faulty.
As pointed out above, there are other limits that apply specifically to idle in DTA ECUs, with maximum and minimum duty cycle values allowed.

As mentioned before check this.