2001 Buick Century engine rough idle

Tiny
JOE1953
  • MEMBER
  • 2001 BUICK CENTURY
  • 3.1L
  • V6
  • FWD
  • AUTOMATIC
  • 180,000 MILES
Engine seem to misfire at idle and the engine service light is on and the computer code is PO171 and P1404 so what is causing the engine to idle bad?
Thursday, May 8th, 2014 AT 1:37 PM

7 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
There is a tsb for this but hard telling if your computer has been updated or not. But check for a stuck open or partially clogged egr and fuel pressure it may be low 41-47 psi autoparts rent gauge
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Thursday, May 8th, 2014 AT 3:54 PM
Tiny
JOE1953
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If the egr valve was stuck open would the engine stall when get of the gas and will the engine code P1404 causing the engine code PO171 and what is the meaning of the PO171 and P1404?
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Thursday, May 8th, 2014 AT 4:38 PM
Tiny
HMAC300
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Yes because an egr open at idle cause a rough idle. 171 is lean engine and 1404 is an egr problem.
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Friday, May 9th, 2014 AT 6:54 AM
Tiny
JOE1953
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  • 635 POSTS
The engine do not stall when take foot of gas pedal so which one do I need to replace the p1404 or the po171? To me it seem like the engine is more like a rich engine.
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Friday, May 9th, 2014 AT 4:36 PM
Tiny
HMAC300
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You need to fix both not just one, check your fuel pressure as well.
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Saturday, May 10th, 2014 AT 5:44 AM
Tiny
JOE1953
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  • 635 POSTS
Are you saying I need to replace the Oxygen Sensor and the EGR to fix it?
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Saturday, May 10th, 2014 AT 5:55 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You need to find the cause of the codes which can be other than what you think they are the p1401 is going to be a bad one to fix because it may need a pcm upgrade if it never has been done. You can change theO2 sensor but that may not fix the code you are getting. But you still need to check fuel pressure with a gauge as that can also cause the 171 code. Replacing parts doesn't always fix the code problem
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Sunday, May 11th, 2014 AT 8:18 AM

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