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Discussion Starter · #1 ·
So I am sure this is not an issue, but my OCD gets the best of me some days... this is one of those days :eek:

So some times, only noticed in the morning (after drive to work so truck is warm) my idle RMP is not as consistent. Its not alot, just barely enough to hear through my loud exhaust. My usual idle is very consistent, around 637-643rpm. When I can hear the slight fluctuation, my CTS reads 631-645rpm. I am pretty sure that if my exhaust was not "unrestricted," I wouldn't even notice or be able to hear it. I have only noticed in the morning, when I park at work. During the day, when its warmer out, I don't notice at all. FRP is always 4.3-4.4 at idle.
 

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Discussion Starter · #2 ·
I figured I would at least get a response of someone telling me I am crazy and over concerned lol.

I noticed this morning that is is more of the upper 620s to 645rpms. Like 627-645. I noticed it cause it is very patterned. Like a constant "vrooom...... vrooom..... vrooom." Its just not a loud vroom cause its not that much of an RPM change.

Once I am out driving during the day, it idles very consistent (637-642). Only happening when I park at work. Morning temps around 65F and afternoon temps around 85F.
 

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Might be the vanes on the turbo cycling while it idles. Just a thought.
 

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Discussion Starter · #4 ·
Might be the vanes on the turbo cycling while it idles. Just a thought.
Thanks for the input! I don't think so, as I monitor the vein position sensor. Wounder what is normal for MAF at idle? Seems like I heard 40g/s? I see 34-36g/s
 

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I believe around 39 is normal and it changes with the temperature, a clogging air filter will lower the reading.
 

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Discussion Starter · #6 ·
I believe around 39 is normal and it changes with the temperature, a clogging air filter will lower the reading.
Just put the filter on a little over a month ago and cleaned the MAF sensor when I changed my oil last week. I am running an S&B dry. It is the older, discontinued model though (75-5058D). I have considered upgrading to the new model (75-5075-1D), but not sure if it is actually worth it lol.
 

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So I am sure this is not an issue, but my OCD gets the best of me some days... this is one of those days :eek:

So some times, only noticed in the morning (after drive to work so truck is warm) my idle RMP is not as consistent. Its not alot, just barely enough to hear through my loud exhaust. My usual idle is very consistent, around 637-643rpm. When I can hear the slight fluctuation, my CTS reads 631-645rpm. I am pretty sure that if my exhaust was not "unrestricted," I wouldn't even notice or be able to hear it. I have only noticed in the morning, when I park at work. During the day, when its warmer out, I don't notice at all. FRP is always 4.3-4.4 at idle.
Your OCD is getting the best of you...>:)

Other things that can cause slight RPM variation is the electrical load, A/C compressor etc.
 
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I have something similar on my lml. Sometimes when I start the truck with the motor warm, it will lope in gear. Not super bad but enough to notice from inside and outside the truck. It always smooths out when I put it into park. Idle fluctuates from ~620 to 650 roughly. Just replaced my FPR with a system saver and it still does it occasionally

No idea what's causing it but it always goes away after driving
 

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Just put the filter on a little over a month ago and cleaned the MAF sensor when I changed my oil last week. I am running an S&B dry. It is the older, discontinued model though (75-5058D). I have considered upgrading to the new model (75-5075-1D), but not sure if it is actually worth it lol.
If you want a no-cost diagnostic, just pull the existing air filter and see what MAF sensor reading you get with no filter. If is is much higher without filter, it MIGHT be the filter, old style or new.
 

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Mine does something like this when I start it up and idle it in the morning. After it warms a bit and settles out it will go something like hmmm.......hmmm........hmmm. About 3-4 seconds apart. To me-it sounds like it’s running in perfect harmony like a well oiled precision machine!!!! The rpms do not change much while this happens. It may be the injectors falling into a specific rhythmic pattern. WTF do I know.. I think you’re good tho for what it’s worth.
 

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Discussion Starter · #12 ·
Mine does something like this when I start it up and idle it in the morning. After it warms a bit and settles out it will go something like hmmm.......hmmm........hmmm. About 3-4 seconds apart. To me-it sounds like it’s running in perfect harmony like a well oiled precision machine!!!! The rpms do not change much while this happens. It may be the injectors falling into a specific rhythmic pattern. WTF do I know.. I think you’re good tho for what it’s worth.
Dear God I have never look at it this way! You're an OCD curing genius! That sounds exactly like what mine does! It so slight , just enough for me to hear. And yeah, RPMs only fluctuate about 15rpms or so, maybe a little more.
 
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Hahaha Excellent!!!
 

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Diesels lope there's no way around that unless you have a VW tdi those are the only one that I have seen that have a oval crank pulley on the timing belt system that retards the timing just enough to get rid of that lope and what have we learned from vw and their diesels lol anyways my totally stock lml has a little bit of lope to it every now and again but I just chalk it up to the awesomeness of the truck I'm driving lol anyways put your OCD into something else like I'm the only mechanic in the shop with a clean toolbox hope you get past this 🙂
 

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Discussion Starter · #16 ·
my totally stock lml has a little bit of lope to it every now and again but I just chalk it up to the awesomeness of the truck I'm driving lol anyways put your OCD into something else like I'm the only mechanic in the shop with a clean toolbox hope you get past this 🙂
Thanks for your input! Yeah I am past it lol. OCD comes in waves. Few days of mostly normal thoughts, few days of noticing something normal and thinking its a problem lol. I probably need therapy :cookoo[1]:
 
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