I've been doing some science experiments with my car today trying to figure out why my idle has gotten crappier lately. Three data points:
1. Earlier this year when I was running stock injectors, my IAC steps would be about 24 at idle. This is with the car in drive, 700rpm idle speed (stock), cooling fan on, 190F coolant, 120F MAT, and check valve in place of PCV. I could pull about 14.5-15" Hg vacuum on my VDO gauge, which seemed OK.
2. Today, with the same conditions except with Red Stripe injectors, my IAC steps are around 30. I pull 13.5-14.5" Hg vacuum at idle, which seems a little low.
3. If I replace the check valve with a Fram PCV valve and run the same conditions, my IAC steps go to 36. I still am pulling about 13.5-14.5" Hg vacuum at idle.
Two questions:
1. What are "normal" IAC readings for a GN in idle with the above conditions?
2. Why would the idle IAC position change when I installed the Red Stripes? How is idle IAC position controlled by the ECU?
TIA,
Mike
checked iac and count was 50, loosened screw to lower, it raced up and now wont go below 81, no contact