Code P0507, rough start and high RPMs?

2001 CHEVROLET SILVERADO
175,000 MILES • 6.0L
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RLPETERSON78
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When I start the truck, it idles rough and may shut down. When I get it started it is fine, but I get a P0507 code, and it idles high.

Now I have replaced the intake manifold gaskets and knock sensor and installed a new connector to the end of the cruise control cable. I have also replaced the MAF sensor.

I attempted to loosen the connector on the cruise control line but that didn't help the high idle. I also have a smoke machine and I hooked it up and didn't find any leaks.

What could be causing the high idle?
Jan 30, 2024 at 2:41 PM
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JACOBANDNICKOLAS
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Hi,

I looked up the code for diagnostic information and ran into a wall right away. See pic 1 below. I need to know if it has electronic throttle control or not.

Also, let me know if you have checked the idle air control valve (IAC).

Take care and let me know.

Joe
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Jan 30, 2024 at 8:20 PM
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RLPETERSON78
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I didn't think that I had an electronic throttle control but, in the photo attached it seems that I do. Do you think either cleaning or replacing the IAC valve would solve the problem.
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Jan 31, 2024 at 9:42 AM
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JACOBANDNICKOLAS
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Hi,

The idle air control valve is the most common cause of this code and conditions. I would remove it to check if it is corroded.

I attached a pic below showing which of the two is the IAC. The other sensor in the pic is the throttle position sensor (TPS).

Let me know what you find with it.

Joe

See pic below.
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Jan 31, 2024 at 1:14 PM
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RLPETERSON78
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I replaced the IAC and the PCV valve and have been driving the truck for a week and no check engine lights have come on. So, I think the problem is fixed. The old IAC wasn't corroded, and the PVC valve was clogged. But changing both solved the problem.
Feb 9, 2024 at 8:06 AM
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JACOBANDNICKOLAS
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Hi,

Thank you for the update. I'm glad you were able to resolve the issue.

Take care of yourself and feel free to come back anytime in the future.

Joe
Feb 9, 2024 at 1:00 PM
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RLPETERSON78
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I spoke to soon. It took more than a week driving my truck to get a check engine light. Now I am getting P0101, P0171, P0174, P0507. I replaced my MAF sensor and the PCV valve. I have a smoke machine and hooking it up, I didn't have any air leaks. I replaced a knock sensor and discovered that one of the sensor lines was beneath the intake manifold after I Torqued it down. Yesterday I took a look at the wires, and I don't see any breaks. What do you think is going on?
Feb 13, 2024 at 4:52 AM
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JACOBANDNICKOLAS
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Hi,

Check the wires that were pinched by the manifold for continuity. Wiggle them around when checking. There could be damage to them under the insulation you don't see.

Let me know.

Joe
Feb 13, 2024 at 6:02 PM
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RLPETERSON78
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Joe,

What is #7 in the engine diagram in this email chain?

Ron
Feb 13, 2024 at 6:59 PM
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JACOBANDNICKOLAS
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Hi,

I believe you are referring to the throttle position sensor.

Let me know.

Joe
Feb 14, 2024 at 6:07 PM