01' Cadi Seville STS NorthStar 4.6 loping idle

Tiny
BASOD2002
  • MEMBER
  • 2001 CADILLAC STS
69000mi. Started by noting a loping idle when I pulled in garage. Drove to work next moring and Check engine light came on at one and only stop light on voyage. Engine Lopes about 100-200 rpm, runs smooth elsehwere. OBD Codes display 0171, 0174, fuel trim lean bank #1, 2. Replaced MAF-not the problem. Replaced Fuel Filter w/ injector cleaner-not the problem. Started and allowed engine to warm up, and then disconnected the low air flow idle valve plug. The loping immediately stopped. I removed the valve and inspected cleaned some carbon, but problem persists. Valve runs about $260, not sure if its getting a message to hunt-from vacuum leaks(Noted some good info on intake leaks in your columns-will inspect for tonight) or if you've ever heard of these motor valves binding up? Checked all vacuum lines and found no obvious cracks/leaks. Have heard that intake silencer can develop cracks-Any ideas on how to remove it(has one of those one time crimp clamps) and be able to reinstall.
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Saturday, June 23rd, 2007 AT 7:00 PM

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Tiny
BUZZSAW
  • MEMBER
Thoes are O2 sensor codes, replace them both, buy GM ones, not autozone( before the catilitic converter )
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Thursday, December 20th, 2007 AT 11:50 PM

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