2016 tahoe ltz feeling sluggish lately

[stormin]

Hi Carl
yes.. that was at the Detroit Autorama.
Thanks for the compliments.

To Ira... Torque converter? hmmmm.. ok.. that's a first I've heard about that type of issue with these but ok will keep that in mind.

ok.. so here's what I hate to admit... I did find part of the problem.
My wife and son recently drove the Tahoe just locally and complained about the same issue... they said.. felt like the parking brake was dragging initially. Well.. my complaint was just sluggish.. but.. not THAT bad.... so thinking further...… I remembered we had some snow here a couple weeks ago. The Tahoe was in a drift in my driveway and not moving... so my wife put it into 4wd.
So I asked her yesterday.... Did you remember to put it back into 2wd? hahahahha… because of course.. I've done the same thing.

of course.. it was still in 4wd. so … silly mistake but that solved the issue that THEY mentioned and otherwise....I still think it's a big sluggish. I will do some maintenance on it.. clean the throttle body.. air filter...check the MAF... and see how it feels after that.

thanks for all the info and ideas everybody!
I appreciate it!

NB

 

[BlaineBug]

Was it in auto or part-time 4x4? I really don't notice much of a difference in regards to feeling sluggish when in auto 4x4 vs. 2 wheel drive. The only difference is I can hear more "noise" up front, probably due to the hubs being automatically locked since they are not locked full time.

If it WAS the torque converter failing I assume you would be experiencing yourself needing to rev the engine more to get it to move, as in requiring higher RPMs. Is this something you notice?

As far as I am aware, the torque converter is essentially a viscous coupling between the engine and the transmission. There is a turbine inside that the fluid gets caught up in to create a sort of fluid friction and creates the link between the engine and transmission. Which is why they generally say vehicles with a manual transmission will have more horsepower and torque to the wheels than the exact same vehicle with an automatic transmission. There are losses due to "slippage" caused by this fluid link.

With that being said, I believe that there are a variety of sensors which measure the difference in rotation between the engine and transmission, and if it gets out of spec, you will get a check engine light and a code that references a mismatch in RPM between engine output and transmission input.

 

[stormin]

Hi Blaine
It was manually switched to 4wd.... I never use the auto feature.
I usually don't notice much difference until the wheels are turned and/or you are on dry pavement.
We did go out Sat evening.. switched back to 2wd and it ran wonderfully.
There is no awkward slippage in the torque converter.. I have experienced that before in my other Tahoe and I did have a transmission put in that one. That was a 2005... another great vehicle!!

I do pull a fairly large trailer with my other car in it during the summer months so I really do make sure I don't over work the transmission since I know i'm pretty much at my max pulling capacity.

 

[BlaineBug]

I find it interesting that the information center would not alert the driver that the vehicle was placed in part-time 4x4 upon initial startup to say the least. Oh well. Glad to hear your issue was a non-issue.

 

[stormin]

Hi Blaine
yes... you ..me and others have said pretty much the same thing.
It informs you that it' switching to either 2wd or 4wd.. but..that's it. no indication otherwise what it's in unless you check yourself.
Lots of other toys on that vehicle that I don't even use... but.. an indicator light for 2 or 4 wd would've been simple enough for gm to put in there you would think?

 

[BlaineBug]

Well there is an indicator light. It i that flea-sized spec of an amber light on the 4x4 knob itself.

But don't worry, if you turn the tailgate OFF, it warns you every time you start up the vehicle, with visual message and audible chime to boot!

 

[Jeramia]

Was it in auto or part-time 4x4? I really don't notice much of a difference in regards to feeling sluggish when in auto 4x4 vs. 2 wheel drive. The only difference is I can hear more "noise" up front, probably due to the hubs being automatically locked since they are not locked full time.

If it WAS the torque converter failing I assume you would be experiencing yourself needing to rev the engine more to get it to move, as in requiring higher RPMs. Is this something you notice?

As far as I am aware, the torque converter is essentially a viscous coupling between the engine and the transmission. There is a turbine inside that the fluid gets caught up in to create a sort of fluid friction and creates the link between the engine and transmission. Which is why they generally say vehicles with a manual transmission will have more horsepower and torque to the wheels than the exact same vehicle with an automatic transmission. There are losses due to "slippage" caused by this fluid link.

With that being said, I believe that there are a variety of sensors which measure the difference in rotation between the engine and transmission, and if it gets out of spec, you will get a check engine light and a code that references a mismatch in RPM between engine output and transmission input.

The torque converter has a clutch which locks up, giving you a direct drive from the engine to the transmission This is were they get the overdrive from, or 6th gear, So when you engage the tow-haul mode you are dis-engaging this clutch from making and also changing your shift points. I think this clutch in the T Q is causing all the problems.

 

[BlaineBug]

Correct me if I am wrong but torque converter lockup is not the same as the overdrive gear.

The overdrive gear has a ratio where the engine output is actually rotating slower than the transmission output is.

Some newer transmissions have two overdrive gears, possibly more.

So for instance on a "vintage" 5 speed transmission, 4th gear would be a direct 1:1 ratio and 5th gear would be the overdrive gear. Therefore, 5th gear gets locked out in tow/haul mode.

I believe the torque converter still achieves lockup when in tow/haul mode. As far as I am aware it would need to lock up no matter what in order to keep the temperatures down which would be especially beneficial when hauling a heavy load.

The lockup clutch in the torque converter is controlled by transmission fluid. So basically it can fail in a way where it never locks up, or it fails in a way where it doesn't unlock, and then your motor bogs down and stalls when you slow down and come to a stop. Such as in driving with a manual transmission and not disengaging the clutch when you stop.