Codes Po300, po301, and p0507, fuel injected locations?

1999 CHEVROLET TAHOE
240,120 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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JLIGHT317
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  • 1 POST
Po300 po301, idle air control higher than expected p0507.
Sep 1, 2025 at 12:37 AM
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STEVE W.
  • ASE Certified Mechanic
  • 15,200 POSTS
  • ASE Certified Mechanic
With those codes it sounds like a vacuum leak. That cause a higher idle because the extra air makes the system add fuel to compensate. The misfire codes would show up for the same reason. Finding the leak will require a visual inspection first, look at the vacuum lines for damage or looseness. If they all look okay take a can of starter fluid or an unlit propane torch and start the engine and move the torch around or spray the fluid on the lines, around the intake manifold and listen for the engine to change. Look in the area that made it change. Then you repair the cause of the leak.


https://www.2carpros.com/articles/automotive-engine-vacuum-leak-symptoms
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Sep 1, 2025 at 7:11 AM
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