IAC Trouble
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IAC Trouble
I have been diagnosing a demon problem with my truck not running right when it warms up. While testing the IAC I have found what I think is odd behavior.
TPS Sensor was at .92 VDC (should be .95, im sure this is good enough)
When I unplugged the IAC, there was NO change in RPM at all. To get it to run rough with the IAC unplugged I had to back the throttle screw completely out, and it still would not die when I unplug the IAC. This put the TPS at .8V. I have smoke tested the truck 3 times and the MAP showed 21-22 inHG of vacuum, I am confident there is not a vacuum leak.
IAC is supposed to have 10.5V at idle, I had 9V, sometimes as low as 8.
While revving the truck up at a standstill it would maintain 9V.
While driving it would hover around 3-5V at WOT.
While cruising on the highway it would hover around 6-7V.
When i had the throttle screw completely out (TPS at .8) I drove it for a day with no change in performace. I put the TPS back to .95 by screwing the throttle screw in to where it was and it has 12VDC at idle. After a couple revs it would move to around 9-10V.
CAn anyone help explain this or provide insight into how the IAC should behave?
Another thread with a different subject on the same problem.
https://www.ford-trucks.com/forums/1...e-bad-pcm.html
TPS Sensor was at .92 VDC (should be .95, im sure this is good enough)
When I unplugged the IAC, there was NO change in RPM at all. To get it to run rough with the IAC unplugged I had to back the throttle screw completely out, and it still would not die when I unplug the IAC. This put the TPS at .8V. I have smoke tested the truck 3 times and the MAP showed 21-22 inHG of vacuum, I am confident there is not a vacuum leak.
IAC is supposed to have 10.5V at idle, I had 9V, sometimes as low as 8.
While revving the truck up at a standstill it would maintain 9V.
While driving it would hover around 3-5V at WOT.
While cruising on the highway it would hover around 6-7V.
When i had the throttle screw completely out (TPS at .8) I drove it for a day with no change in performace. I put the TPS back to .95 by screwing the throttle screw in to where it was and it has 12VDC at idle. After a couple revs it would move to around 9-10V.
CAn anyone help explain this or provide insight into how the IAC should behave?
Another thread with a different subject on the same problem.
https://www.ford-trucks.com/forums/1...e-bad-pcm.html
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