RPMs jump up on highway at random

[Thunderbone]

I've got a 2014 Silverado 5.3L and my issue is when I'm driving on the hugh way at 60mph with cruise control on and on flat road every now and again my RPMs will jump around 300 to 400 rpm then settle back down to about 1500rpm. Is this normal? Is this when it switches from V8 to V4? Or is it the torque lockup solenoid on the fritz?

[2strokesmoke]

I've got a 2014 Silverado 5.3L and my issue is when I'm driving on the hugh way at 60mph with cruise control on and on flat road every now and again my RPMs will jump around 300 to 400 rpm then settle back down to about 1500rpm. Is this normal? Is this when it switches from V8 to V4? Or is it the torque lockup solenoid on the fritz?

Sounds like a tranny issue, either in the t/c or possibly a bad solenoid like you mention.

[fondupot]

AFM does not cause a change in RPM. A jump that drastic has to be a trans issue.

[nluchau]

AFM does not cause a change in RPM. A jump that drastic has to be a trans issue.

My AFM when changing to V4 causes a slight increase in RPM. Nothing like the OP is mentioning though.

[dorkweed]

Is a "hugh way" a Canadian thing???

 

Sounds like a torque converter/tranny issue.

[2strokesmoke]

I've got a 2014 Silverado 5.3L and my issue is when I'm driving on the hugh way at 60mph with cruise control on and on flat road every now and again my RPMs will jump around 300 to 400 rpm then settle back down to about 1500rpm. Is this normal? Is this when it switches from V8 to V4? Or is it the torque lockup solenoid on the fritz?

Make sure your cruise control works! Brake pedal switch controls cruise control, stop light, and a signal to the transmission control unit. Donot confirm it's operation solely by means of a brake light test, as it controls 3 switches signals.

 

If the data signal to the bus controler is sticking (brake pedal switch) the transmission will behave strangely and cruise control usually will not work while driving within the first 1-2 minutes of first drive of day. If cruise does not engauge properly, try lightly taping your brake pedal while cycling your cruise to set. If your cruise begins to work after lightly taping brake pedal, your stop switch is failing or damaged.

 

If all above works fine, suspect your torque converter or transmission being the culprit. A weak or failing solenoid can cause weird issues, but the Torque converter could have a hairline crack, known problem with some.

 

Best of luck

[fondupot]

My AFM when changing to V4 causes a slight increase in RPM. Nothing like the OP is mentioning though.

 

It's not AFM causes the change in RPM though. It's likely the Torque converter locking/unlocking.

[nluchau]

 

It's not AFM causes the change in RPM though. It's likely the Torque converter locking/unlocking.

So cruising down the interstate at 70 the TC is locking and unlocking? Every time mine switches to V4 on interstate there is a small fluctuation of RPM.

[fondupot]

So cruising down the interstate at 70 the TC is locking and unlocking? Every time mine switches to V4 on interstate there is a small fluctuation of RPM.

Think about it. The engine rpms aren't changing just because half the cylinders deactivate. It has to be something else. The TC constantly adjusts based on the terrain and load on the vehicle.

 

 

Sent from my iPhone using Tapatalk

[EFLine]

Mine does this all the time and drives me nuts. I have the same issues as the OP and definitely notice it when it changes from V4 to V8, and yes 300-500 RPM jump from switching both ways, from V8 to V4 and V4 to V8. I call it surging and actually posted about it a while ago.

 

Sorry I do not have an answer or solution, but I experience the exact same thing

[firecat_30]

It's your torque converter. My 2015 Denali did this. Granted mine had the 6.2 and 8 speed but what your explaining is the same. The converter would not lock and was slipping as it was trying to lock. I tryed everything and the dealer had truck more then I did so I traded the truck in.. good luck, hopefully if that is your problem they can fix it

[Recks]

On 4/28/2017 at 2:32 AM, Thunderbone said:

I've got a 2014 Silverado 5.3L and my issue is when I'm driving on the hugh way at 60mph with cruise control on and on flat road every now and again my RPMs will jump around 300 to 400 rpm then settle back down to about 1500rpm. Is this normal? Is this when it switches from V8 to V4? Or is it the torque lockup solenoid on the fritz?

Did you get this issue figured out? I have a 2018 with the 6 speed and it’s doing the exact same thing. Thanks.