socal01denali

with about 52,000 miles ive been experiencing a problem with my idle it usually happens when i first start up the truck before i push the pedal hot or cold and sometimes at a stop light. it doesnt seem to matter if the a/c or headligts are on. the idle will drop and rise from normal idle speed (around 600) or so to around 100...my headlights and a/c if on will dim and come back with every rpm strike and my battery volts guage will steady drop from 14 volts in sequence with the rpms until i gas it or drive off. i recently installed a new 135 amp alternator because my stock 130 amp was only putting out around 4 amps at 2000 rpm.so i thought that was it... the problem happened that same night. i run 91 octane fuel, occasionally use carb/injector cleaner with a fill up ,my battery reads good, my charging system is good and my fuel filter is clear. any ideas you might have would be great thanks in advance

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peace, ryan

GMMerlin

First I would clean the throttle body...deposits on the blade and bore will cause low idle concerns.
If it is a cable actuated throttle body, there is a GM technical bulletin to resolve this issue.
Next, only use the octane rating specified by GM for that engine...using a higher octane fuel can cause cold driveability issues and you are just wasting your money on something you dont need.

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GMCTech

Clean the throttle body bore as GMMerlin said.

Also GM has a few software updates addressing idle surge and fluctuation. I'm not sure if your vehicle has this availalbe to it, but it's worth the check.

Hope this helps.

socal01denali

thanks guys...i will start with the throttle body..HEY GMCTech do i have to go into GMC and pay them....i was planning on getting a hypertech programmer soon...do you think it will have any of these updates??

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peace, ryan

socal01denali

my trucks a 2001 so i figured 91 octane would be fine and even provide a little better performance...but ill check the book

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peace, ryan

GMCTech

Most likely the hypertech programming will overwrite anything the dealership does, try that first if that's your plan.

socal01denali

hey gmctech i cleaned out the throttle body with some valvoline synthetic cleaner for carb, throttle body and choke...you guys were right it was pretty filthy and i have the rag to prove it...a put in a few good sprays finished installing my new volant intake then drove around...i will have wait and see if the cleaner helped with my idle issue...but about how much should i spay into the body interior?? thanks!! also to any yukon owner out there i definetly recommend the volant cold air for your truck WOW awesome performance, great low end pick up and response, afforadable and kick ass sound!

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peace, ryan

socal01denali

i guess i should have said how much should have i sprayed or were a few healthy sprays sufficient? thanks

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peace, ryan

Tony Denali

you have the drive by wire system. No cable. My Denali did the same thing and just took it to the delear for a software update and it took care of it pronto.

ranman7

check out the recall on the 01 yukon for a misrouted positive battery cable which rubs on the steering shaft and causes different elec. problems