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4.2 inline 2006 120.000 miles. all stock , starting to idle rough. Needs tuneup, what all needs to be changed.
 

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2008 chevy trailblazer_lt
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26 Posts
Take it to an auto parts store and they can scan for codes.
Probably the spark plugs and the 02 sensors.
 

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2005 chevy trailblazer_lt_ext
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At 120,000 miles, i would change spark plugs, transfercase fluid, front snd rear differential oil, transmission oil. Clean the throttle body, replace the serpintine belt. Oil change.. thats about it.
 

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2004 gmc envoy_slt
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2,247 Posts
Do not gap iridium plugs, you can damage the plug, they come already gapped.

If you stick with name brand filter, like AC Delco, you will be fine.
 

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2003 gmc envoy_sle
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Tune up 120k miles

I have a 2003 envoy and did all that has been indicated, the plugs and cleaning the throttle body solved my idle concern.
 

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2005 chevy trailblazer_lt_ext
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I will vouch for NOT gapping the plugs. I thought I was carful and ended up having to replace some plugs after only 4,000 miles. My bad.
 

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2005 gmc envoy_denali_xl
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Tuneup

I think the first and least expensive thing to start with is to Clean the throttle body, my 04 Trailblazer did that at 104K and as soonas I did it the problem cleared away.

Best of luck.
 

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gmc envoy_sle
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11 Posts
Check the variable valve timing solenoid Search Common Problems with envoy on YouTube and click The Car Doctor Very good information
 

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2006 chevy trailblazer_lt
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At 120,000 miles, i would change spark plugs, transfercase fluid, front snd rear differential oil, transmission oil. Clean the throttle body, replace the serpintine belt. Oil change.. thats about it.
Cleaning the throttle body will do wonders... I also did/do the Seafoam through the intake from vacuum line off of brake booster. Tune up I did at 90K Trailblazer now has 130K. Keep the throttle body clean and the valves and pistons with the seafoam and it will run and idle like a champ.
 

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2006 chevy trailblazer_lt
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4.2 inline 2006 120.000 miles. all stock , starting to idle rough. Needs tuneup, what all needs to be changed.
Just so you know... I had the same issue and after I did everything listed on here it still had issues idling only to find out that I had a broken motor mount. So if everything else fails you may want to check that.
 

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2006 chevy trailblazer_ls
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It's not necessarily a tune-up rather more Maintenance.

you said it's running rough? clean or change the mass air flow sensor then you can move on to list below

(do this every time you change your oil.)
Change engine oil and filter. Reset oil life system. An Emission Control
Visually check for any leaks or damage.
Inspect engine air cleaner filter. If necessary, replace the filter.
Rotate tires and check inflation pressures and wear
Inspect brake system.
Check engine coolant and windshield washer fluid levels and add fluid as
needed.
Perform any needed additional services.
Inspect suspension and steering components.
Inspect engine cooling system.
Inspect wiper blades.
(do this at 100,000 miles)
Inspect restraint system components.
Lubricate body components.
Inspect fuel system for damage or leaks
Inspect exhaust system for loose or damaged components.
Replace engine air cleaner filter Change automatic transmission fluid and filter (severe service).
Change automatic transmission fluid and filter (normal service).
Automatic transfer case only: Change transfer case fluid.
Replace spark plugs: An Emission Control Service.
 

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2002 gmc envoy_slt
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32 Posts
Gap i think changed

Just bought ac delco 41-103 iridium as rockauto and others state this is the current correct plug. Owners manual said gap was 50 on the old 41-965, however rockauto is showing 43 for the 41-103. I recall reading the reason why somewhere on here I think. Not sure what they are gapped to at factory, as the only thing the box says is "set gap per vehicle specifications".
 

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Tuneup

I think the first and least expensive thing to start with is to Clean the throttle body, my 04 Trailblazer did that at 104K and as soonas I did it the problem cleared away.

Best of luck.
I did the same and changed my air filter and seems like a totally different vehicle
 
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