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My daughter's car. Code P0505. No freeze frame data for this code on my code reader. Car starts and idles OK, albeit a bit slow, in park. I would estimate idle is about 650 rpm with car in park. It definitely sounds a bit slow and feels a bit weak. As you add loads, such as shifting into Drive and engage the AC, idle does not increase sufficiently to compensate. Add enough loads and it stalls pretty much every time. Runs fine at highway speeds, but come to a red light and it will stall unless i shift into neutral and press the gas a bit. Things i have checked: 1. Manifold vacuum, to rule out exhaust restriction. Reads steady right in the middle of the green zone on the guage, around 20 in/hg. Behaves at it is supposed to when i do a snap-throttle. So I don't think there is an exhaust restriction. 2. EGR: When I disconnect the egr valve vac line and connect it to my vacuum "gun" at a steady idle, I can kill the idle every time by applying vacuum to the egr valve. So egr doesn't seem to be stuck. I do not have a scope so I can't check the wave-forms on the six wires that connect to the IAC valve. Guys, are there any other low-tech ways that would enable me to rule this IAC in or out as the cause of my idle problems? Thanks, Pop
I found (on Autozone repair web page for this car) and performed a couple of tests that they advised.
First, it said to put a stethoscope probe on the body of the IAC motor and listen for clicks when key is turned from the OFF to the ON position. I did not hear any clicks when going from OFF to ON, but I did hear a few clicks when key was turned back to OFF position. So, technically speaking, this test was inconclusive.
The procedures further stated, that if the "click test" is passed, to check the resistance of the motor itself. Even thought thee first test was inconclusive, I went ahead and did this test as well. Resistance test said to check the resistance between pins 1 and 2, and 2 and 3. Resistance should be between 28 and 33 ohms at each interval. I found resistance between 1 and 2 to be 4.5 ohms. resistance between 2 and 3 was 8.3 ohms. Procedures further said to test resistnce between pins 5 and 6 and 6 and 7. resistance between those were in the spec of 28 to 33 ohms.
My question is, Are any of these tests meaningful, since the first test was inconclusive, and the instructions were to continue IF first test was passed?
It seems to me the resistance checks on the motor should be within spec regardless, which they are not in this case, but then again this IAC motor is pretty expensive, my knowledge is limited, and I don't want to fall victim to the Curse of the Parts Changer.
I would of thought the evidence of the ohms reading being low on the IACV was enough to change it. They have very thin windings and the ohms readings should be accurate enough
