2016 Silverado crew 5.3 6 speed z71 acceleration question

[nluchau]

Hello, 

 

One thing I've noticed on my truck when accelerating going through the upshifts after a cold soak is this: (Bare with me as I best describe this) Lets say I pull out of my work parking lot where I need to accelerate to get up to 40 mph.  I feel at about 30 mph what seems to be like a power band kicking in or a surge, it only happens once after each cold soak. After that I don't feel it, just the first time accelerating after a cold soak.  Am I feeling the torque converter lock up?  If so, is this normal behavior?

 

Thanks  

[Sierra Dan]

Cold Soak?  You mean completely cool engine?

[nluchau]

12 minutes ago, Sierra Dan said:

Cold Soak?  You mean completely cool engine?

Yes

[pronstar]

Cold soak is a new term to me.

Maybe it’s shift flare...?


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[Hate Work]

Doesn't a tranny have to warm up too? How do you respond first thing in the morning? Do you jump out of bed and do 100 yard gassers?

[SILVER SLED]

Probably shift flare.  Try shutting truck off, key out, opening and closing the driver door and try it again.  It will probably do it again on acc.  Seems like it does this on initial acc, not necessarily cold "soaks".  

[nluchau]

3 hours ago, Hate Work said:

Doesn't a tranny have to warm up too? How do you respond first thing in the morning? Do you jump out of bed and do 100 yard gassers?

I realize what your saying but I am just wondering what exactly it is and I'm sorry if my description of it isn't clear.  If it's doing something it needs to do in warming up that's ok.  

[nluchau]

So when I left work today, it did it again and I paid closer attention to the RPMs. What I noticed is right when it lunged forward or surged it up shifted.  It felt like a quick blip of the throttle was added into the acceleration I was giving it.  I'm not that concerned about it but does anyone else experience it?  After that initial one it didn't do it again.  

[nluchau]

3 hours ago, SILVER SLED said:

Probably shift flare.  Try shutting truck off, key out, opening and closing the driver door and try it again.  It will probably do it again on acc.  Seems like it does this on initial acc, not necessarily cold "soaks".  

Worth trying just to see what it does. Thanks for the suggestion.  

[Hate Work]

8 minutes ago, nluchau said:

I realize what your saying but I am just wondering what exactly it is and I'm sorry if my description of it isn't clear.  If it's doing something it needs to do in warming up that's ok.  

Let's see. How do you spell idiosyncrasy? My 5.3, when it's cold has a "funky" shift from first to second. Kind of slow and then jerky. Once it warms up, all is AOK. I have just written mine off as "idiosyncrasy. 

[Sierra Dan]

Life is like a box of GM Transmissions....

You never know what you'll get!  

[adock22096]

I know I don’t have anything close to the same vehicle but my 2011 Forester does what you described. I assumed it was just the ECM or TCM limiting power until proper operating temperatures are reached. I believe most vehicles change air fuel ratios when cold to more quickly reach operating temps so that may have something to do with it as well. 

[nluchau]

On 9/1/2018 at 10:35 PM, adock22096 said:

I know I don’t have anything close to the same vehicle but my 2011 Forester does what you described. I assumed it was just the ECM or TCM limiting power until proper operating temperatures are reached. I believe most vehicles change air fuel ratios when cold to more quickly reach operating temps so that may have something to do with it as well. 

Thanks for chiming in adock22096 - I bet you are exactly right.  It doesn't seem to be a problem and only happens when cold.