Pwm valve frequency is the Hz the valve will work at. I have found that in closed loop 279-311 Hz works well.I have a question in regards to the PWM idle valve (IAC). Can someone explain what increasing or decreasing the Valve Frequency does?
I have a weird issue that I have been chasing regarding idle. My idle control algorithm is set to Open-Loop, and with the tune being the same I get two different idle rpm of one being around 811 and the other 850 (these are averages over a few minutes) The AFR ratio is higher on the 811 rpm, which makes sense its getting less air and more fuel and the 850 rpm one is perfect. Of course, I am chasing the 850 rpm target as it gives a perfect smooth idle even with an E303 cam. The idle issue doesn't change during driving at all it stays the same the hole time. The idle s is a random idle issue too meaning that I can drive the car 3 times and the idle be at 811 and then the next time you drive the car its at 850.
Today I drove the car to work and it was perfect at 850, but yesterday it was at the 811. It is not due to headlights or voltage draw since both of those days where the same as well. This got me thinking that maybe its the valve frequency or the valve is going bad.
Any feedback would be great.
Typically the higher this is Set to the less precise the valve becomes, however at least my car the valve screams at lower Hz settings.
What are your mat temps on these different days? You could have ignition retard affecting idle speed. As little as .5* timing can lower and raise idle speed.