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2005 chevy trailblazer_ls
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28 Posts
Discussion Starter #1
Have a 2005 TB LS with 4.2 with 180k. Just recently noticed a gurgling noise coming from the intake at idle. I pulled the air cleaner cover off, and sound got louder. Pulled radiator cap off, radiator and overflow are full, and coolant has good color. Left the cap off and let it run for 5 minutes, no bubbles were visible. The only code is one that has been there for a while P0128, coolant temp below thermostat regulating temp.

Lately temps have been highs of 10, then the past couple days it has gradually warmed to almost 50. Don't know if that will matter, but figured I'd include it just in case.
 

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2004 gmc envoy_sle_xl
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1,239 Posts
Don't know about the gurgling sound, but you need to take care of the P0128 issue. This usually cause by a stuck open or lazy thermostat. With the engine temperature not reaching full operating level, the PCM will feed more fuel and that will cause the catalytic converter to clog.
 

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2005 chevy trailblazer_ls
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28 Posts
Discussion Starter #3
It doesn't seem to be affecting anything. Still getting about 17mpg, and it's up to operating temp in about 2 miles at 45-55mph, then will stay at between 200-210.

I've got a new thermostat and ect sensor, just waiting for it to warm up a bit before I put em in.
 

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2005 chevy trailblazer_ls
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Discussion Starter #4
UPDATE:

Dug a little deeper tonight. Source of the gurgling noise is the secondary air system. Just sounded like it was coming from air intake because of the hose that goes to the bottom of the intake tube. Squeezing the hose, I can feel pressure pulsations, that match up perfectly with the gurgling. Plug the hose and the sound goes away.

Read some threads on here saying it could either be AIR pump or the diverter valve. Didn't crawl underneath to see if fluid is present at the pump yet.
 

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2005 chevy trailblazer_ls
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28 Posts
Discussion Starter #5
UPDATE 2:

short term fuel trim is at nearly +17%
long term fuel trim is nearly +30%

New code popped up, bank 1 lean.

Doesn't the AIR diverter valve inject fresh air directly above the oxygen sensor?
 
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