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intermittent start and rough, high idle. 06 gt

  • Thread starter Thread starter Woe06
  • Start date Start date Jan 7, 2026
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    2006 gt high idle
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Woe06

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Jan 7, 2026
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Jan 7, 2026
#1
  • Jan 7, 2026
  • #1
Car threw a P0174 too lean code it either starts right up or takes 5 seconds to start. The idle jumps between 750-1000, and the throttle position is at 12-13% at idle.
With the car on and the engine off, the throttle makes a loud whine when opened.

Hoping someone can offer their expertise on what the issue could be, let me know if y'all have any questions.
 

Mcmahst

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Jan 19, 2021
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Jan 7, 2026
#2
  • Jan 7, 2026
  • #2
All I can think of is it has a vacuum leak, but with the engine off, not sure. Good luck. Way smarter folks will chime in.
 
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Woe06

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Jan 7, 2026
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Jan 7, 2026
#3
  • Jan 7, 2026
  • #3
Mcmahst said:
All I can think of is it has a vacuum leak, but with the engine off, not sure. Good luck. Way smarter folks will chime in.
Click to expand...
I did a smoke test and couldnt find anything. fuel pressure looked good, too.
My best guess is that the throttle body motor or position sensor is going out, but I was hoping to get some help before i start throwing parts and money at it.
 
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Noobz347

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Jan 7, 2026
#4
  • Jan 7, 2026
  • #4
Check fuel pressure after prime but before start and see that it ramps up and holds.

Get a read on your fuel pressure with the engine running.
 
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