SidWell Posted January 18, 2009 Share Posted January 18, 2009 MT 2.25p3 v2.88 I have been trying to set my idle with my IAC stepper motor. I have a Dark Star IAC body. Idle Control Start Value is 160, Crank Position extend is 100 steps. I have been trying to adjust the idle speed when the engine is warm. I have varied the idle steps at 160 degrees from 10 to 200. All with no visible change. Should I be looking somewhere else to adjust the idle speed when the engine is warm? I have confirmed that the stepper does bottom out at initial reset and then backs off to allow air to flow. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted January 19, 2009 Share Posted January 19, 2009 What's the minimum number of steps you have it set to move the IAC at a time? Try increasing it from 1 step to 5 or so; we've found some types of IAC valves seem to get stuck if you don't try to move them several steps at a time. Quote Link to comment Share on other sites More sharing options...
SidWell Posted January 20, 2009 Author Share Posted January 20, 2009 MS 2.25 p3 MSII Rev 2.668 V3 main board. Today I found that it takes 210 steps to fully close my IAC. Full open is 120 steps. Further opening will not increase air flow thru the IAC body. I am using the jeeps stepper motor and the Dark Star IAC body. The stepper motor does not seem to close as the engine warms. I have adjusted the IAC steps at 130 and 160 degrees from 5 to 220 steps and saw no change in the idle speed. I have jumpered the two current limiting resistors, I have changed my minimum step count from 1 to 5. I have increased my pulse width to 4.0 msec. I can put my thumb over the intake side and the engine idle drops to about 500 RPM. This tells me that the stepper is not closing fully. What adjustment should I use to try and run the stepper motor? I was trying to use the Idle Steps tool in Other Tuning. Is it possible that I have the flow direction backwards? The air flow should push against the pindle correct? Which direction is the air flow thru a Dark Star IAC body? Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted January 20, 2009 Share Posted January 20, 2009 You can plumb the block up either way. However, I strongly recommend upgrading to the 2.8xx code series, as these fixed a couple of bugs in the stepper IAC control routine. Quote Link to comment Share on other sites More sharing options...
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