Why does my car idle to high

Tiny
PONTIACBIRD
  • MEMBER
  • 1990 PONTIAC FIREBIRD
  • 190,000 MILES
Car idles high. Without foot on gas car runs at about 20mph. Help! I need to get it smogged but cant unless it idles right!
Friday, August 26th, 2011 AT 10:10 PM

1 Reply

Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
With the mileage you have I would not doubt if the throttle bady butterly plate is getting stuck from sludge ancarbon.
Check in der the and grab the butterfly<(remove intake tract so you can see butterfly), and turn it back and let it snap shut. It should close all the way flsuh but you will see either hols in plat or small gaps to give it enough air to idel. Maybe the Idel Air Control Valve, (IACV) is stuck in a fully loaded position. The IACV turn idle aup as load fromA/C, power steering, etc. Make load demands at idle that it keeps a steady idle with increase or decrease in load.
You might get some cans of SEA FOAM OF BG44K fuel system cleaner and run 2 cans and then change the oil. You have to change the oil because they work so welll lots of the buildup they clean up ends up in oil.
Let me know how it goes.
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Friday, August 26th, 2011 AT 10:40 PM

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