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P0300, high idle,

Originally Posted by Kmccarthy714 Your idling high because your car is LEANING OUT, most definitely start with vacuum leaks, hoses throttle body intake manifold. Move onto sensors that read air

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Old 11-14-2013, 01:22 PM   #30 (permalink)
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Originally Posted by Kmccarthy714 View Post
Your idling high because your car is LEANING OUT, most definitely start with vacuum leaks, hoses throttle body intake manifold. Move onto sensors that read air flow, I.E Bank 1 Air Fuel sensor and bank 2 Air/Fuel sensor. Next move to MAF's(not likely as you would throw a Air Fuel code and the air fuel sensor.

Bottom line
1)Vacuum leak
2)Sensors monitoring vacuum and air
3)Exhaust leak BEFORE A/F SENSOR
4) Fuel drop off causing car to throw more air through the chamber

Check by disconnecting MAF's and seeing if idle changes or fluctuates at all that will rule out the sensors.
First off, this is a 7 month old thread that was already resolved.

Second, you're re-hashing what others have already said (including myself in a bulleted list on the first page).

Third, in testing I've performed since this thread was concluded, I can actually say that MOST vacuum leaks on this car, the car will adjust idle around it and stabilize somewhat close to the commanded idle speed unless the leak is absolutely massive.

Case in point, i can disconnect one of my catch cans from the intake manifold (big nipple on the front of the plenum), and briefly (3-5 seconds) it will surge up to around 1800rpm, but it will quickly adjust and go back to almost normal.

This wasn't something I was doing for fun, was doing some diagnostics, and I never tried disconnecting both of them, that would likely be too much of a leak.

Anyway, yeah. Thread is over and done with anyway.
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