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Author Topic: 2012 5.3 Vortec variable idle  (Read 70 times)

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Offline stewie

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2012 5.3 Vortec variable idle
« on: August 15, 2018, 08:00:43 AM »
Had my sierra tuned up a few weeks ago after a check engine light due to misfires. New plugs, wires and a FI cleaning.
The idle after was eerily quiet. the truck was silent at idle - awesome.
But after a tank of gas the variable and sometimes rough idle came back. It normally idles around 525 or so, but dips to 500 and yesterday was idling around 600/650 for a while.
I read I need to clean the throttle body as this may be the issue, but i'd like to know if there is anything else to look at.

K&N filter (new)
No check engine light
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Offline EL TATE

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Re: 2012 5.3 Vortec variable idle
« Reply #1 on: August 15, 2018, 01:21:49 PM »
clean the MAF sensor, inline between the filter box and the hose. 1st, unplug while idling and check for changes, should jump up. use electrical parts cleaner, or MAF cleaner specifically. if that doesn't fix it, you can check resistance to it with an OHM meter, but I'm not the guy to walk you through that one. Ken?
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Offline KensAuto

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Re: 2012 5.3 Vortec variable idle
« Reply #2 on: August 15, 2018, 01:40:49 PM »
We clean the Tbody when we do tune-ups, just because of that particular issue.

Just seen that you had a K&N. Did the issue begin after installing the K&N? if so, do what Tate suggested. Might have oil on the maf.
« Last Edit: August 15, 2018, 01:43:02 PM by KensAuto »
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Offline stewie

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Re: 2012 5.3 Vortec variable idle
« Reply #3 on: August 15, 2018, 02:32:47 PM »
thanks guys.

the K&N has been in the truck for about 2 months or so. i will however check that again, too.
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Offline stewie

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Re: 2012 5.3 Vortec variable idle
« Reply #4 on: Today at 10:32:06 AM »
cleaned the MAS last evening. pretty easy.
after more research, i think the throttle body needs to be cleaned. I read about K&N filters being overoiled which can cause some gunking. the truck has 130K plus on it so it's probably in order anyway.
The job seem pretty easy
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Offline TexasRedNeck

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Re: 2012 5.3 Vortec variable idle
« Reply #5 on: Today at 01:56:54 PM »
Yeah I stopped using oiled media for that reason


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Offline KensAuto

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Re: 2012 5.3 Vortec variable idle
« Reply #6 on: Today at 06:24:01 PM »
Yeah I stopped using oiled media for that reason


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