2002 Yukon Idle Speed

[bills02yukon]

My 2002 Yukon 5.3 idles right around 500 rpm when warm and the A/C on. If you turn the steering wheel slightly the rpm's will drop and it will sound like it wants to die for a second or two. I've cleaned the throttle body, MAF sensor, air filter, and removed the IAC valve and cleaned it. While it was out the tip of the IAC valve popped off and I re-attached it but am now wondering if that's what is still causing the low idle by being a step of two off. I had it at the dealership this morning and they updated the computer.

 

[imi4tth3w]

sounds like combination of possibly low idle, as well as the power steering pump putting extra strain when you turn. probably some worn out pulleys putting strain on the motor at low rpms..

 

[ccapehartusarmyINF.(ret)]

okay what your describing is normal i have a 2002 my idle speed is always around 500 rpm
and the reason why when you turn the steering wheel at idle is because the powersteering pump runs of the serpentine just like the AC and the water pump alternator and fan
and the power steering pump is hydraulic so when you move the wheel it adds a load to the engine wich is why th reason for the sudden dip in rpms
and if they didnt tell you this at the dealer ship you need to never go back there again

an idle speed of around 500 rpms when its warm wich is closed loop is normal
now when its in open loop it should idle a smidge higher

 

[rockenthebowtie]

The IAC is fine once you reinstalled the plunger back the ecm will relearn the stepper motor counts immediately.... You might want to check for vacuum leaks at the base of the upper intake manifold gaskets by spraying the same throttle body cleaner and listen closely if theres a change in idle if so replace gaskets

 

[bills02yukon]

I didn't know for sure what the idle speed should be. My wife's aunt has a 2002 GMC Sierra 2500 6.0 and it idles at 600-650 all day.

 

[01ssreda4]

Tps can cause goofy idle but 500 (per the gauge) is about what everything idles at nowadays. You may just need a tune up, plugs, wires, 02s etc.

 

[rockenthebowtie]

I also have a 6.0 and it idles 6-650 and also a GM certified for over 25 years do this for a living. Look for vauum leaks its thee most common cause for your type concern... not here to boost or toot my horn just here to give back with what Im very thankful on what I've been blessed with and able to take care of my family with. I hate arrogance and thats not what I'm about

 

[BRUTUS_T_HOG]

An unmetered air leak will cause a low idle on a MAF equipped fuel system. Any loose hoses? Wiggle the intake boot and see r the engine stumbles.

Should idle around 650

 

[01ssreda4]

Shoulda woulda whatever. What is the idle in the tune set for and what is it actually idling at? Yall really like to chase your tail with this zero credible information garbage. Do not trust a factory gauge to be dead nuts accurate, and its VERY common for engines to idle in the 500s, in all makes and models. That 650+ idle is stone age thinking. Find out what your stock tune calls for, find out what your ACTUAL idle is, then determine if there is actually an issue. My bet is it is idling where its supposed to.

---------- Post added at 12:01 PM ---------- Previous post was at 11:58 AM ----------

2002 Yukon, 5.3 stock settings.
Temps................111 133 154 176 198 219 241 262 284
In Gear AC off 665.0 625.0 585.0 550.0 550.0 550.0 550.0 600.0 600.0
In Gear AC on 665.0 625.0 585.0 550.0 550.0 550.0 550.0 600.0 600.0
P/N AC off 665.0 625.0 585.0 550.0 550.0 550.0 550.0 600.0 600.0
P/N AC on 665.0 625.0 585.0 550.0 550.0 550.0 550.0 600.0 600.0

 

[ccapehartusarmyINF.(ret)]

dude i was basically thinken same thing because the tacometer in the tahoe isnt that accurate to begin with because between 500 nd 600 rpm that needle dont move much

 

[01ssreda4]

Well Ive provide actual data from a stock tune so he can get closer to resolving his issue. When someone guesses, and someone hears it, they pass that info along as fact the next go round. That's how we become dumber. I wish if people didn't know they would be quiet and wait for someone to come along that does (this isnt aimed at anyone in particular), so only the best/most accurate info gets passed along.

 

[ccapehartusarmyINF.(ret)]

yeah i make it a firm policy of only providing factual information when responding to a question or helping someone troubleshoot hell sometimes when i know exactly how to fix a problem or exaclty whats wrong ill go research real quick to confirm before i post

okay i just did a little maintenance today and while i was at it i plugged my elm 327 and pulled up the live data in torque the ob2 app and my tahoe idles in the 595 to 605 rpm range and thats the stock tune

 

[rockenthebowtie]

So in other words what your saying is that his idle stumble with ac on while turning at low speeds/idle is normal ? I dont have those app data viewer I have what is call a Tech 2 with a candi module not sure if your familiar with and hook that thing up on a daily basis to scan GM vehicles for everything from airbag lights to ALRC module... EBCM... HVAC... VCIM... PCM/ECM... TCM.. IPC... TAC module.. Software updates... this thing does it all yes the TACH is not always dead on on the IPC but one thing I can tell you is my 02 U motor and wifes 04 Sub T motor, with all the latest GM software updates to every module on my vehicles that I programmed myself and every other vehicle I work on with in that range keeps an idle above 600 with AC on Idle will dip slightly below 600 with absolutely no stumble with P/S load and thats looking at Tech 2 data.. and believe me I would never be able to get away with telling a customer that that is normal..

 

[01ssreda4]

A slight dip is normal, a stumble isn't. I suggest a tune up in my first post. That meant a thorough examination of most items under the hood, hoses, filters, and anything else that might look suspect.

 

[rockenthebowtie]

Say guys I'm not here to sound or come off as an A Hole and if I did I do apologize those are not my intentions here I'm here like you guys just looking to help not to have a battle of who knows how much then the other guy or anything like that what's so ever again I've opened up to you guys on my background and have a great resource of information at my finger tips and always willing to help hope you guys are cool with this and look forward to teaming up with you guys to help out here .. PEACE !!