Jump to content

RPM fluctuating

MrNasty
 Share

Recommended Posts

MrNasty Enthusiast

MrNasty

Posted
Posted

I have have noticed that my needle in the RPM gage is fluctuating. I cant feel the truck surging but I can hear it in the exhaust. Has anyone else experience this issue? Truck seems to run fine otherwise. It does it when I get up to speed like 50 or so and I level off and stay at that speed for a bit, then needle starts to pulse up and down and I can hear the exhaust note change.

 

 

Sent from my iPhone using Tapatalk Pro

mookdoc6 Senior Enthusiast

mookdoc6

Posted
Posted

Your a feather foot! You will not notice if your RPM's are higher....It will always do it because its part of the deal with v4/8 switching. Other option is defeat the V4 or go with a FERD ecoboost? I would recommend you go with tune or stay in manual Mode to defeat the V4!

MrNasty Enthusiast

MrNasty

Posted
  • Author
Posted

I do have the V4 turned off. If i keep it at a steady speed is when the needle jumps up and down. I haven't gotten on the freeway and checked it out yet. I heard it in the exhaust first and then started to pay attention to the rpm once I heard it and saw it jumping up and down. Its not a lot but its moving. I dont know if its its been doing it the whole time I have owned the truck or just started because you cant really feel. Just hear it then see it in the gage. Figured I would have dealer check it any way. Im sure they will say its normal at guys have had some obvious problems and dealers seem to blow them off, but worth a shot.

 

 

Sent from my iPhone using Tapatalk Pro

lba0213 Enthusiast

lba0213

Posted
Posted

Mine started this way. Now I have full on shudder when the needle jumps. Do you feel any vibrations when the needle jumps? The tach is jumping bc the torque converter isnt working properly. Do you have an 8 speed?

truckguy82 Senior Enthusiast

truckguy82

Posted
Posted

Mine started this way. Now I have full on shudder when the needle jumps. Do you feel any vibrations when the needle jumps? The tach is jumping bc the torque converter isnt working properly. Do you have an 8 speed?

if it's a '15 6.2, he has an 8speed

Towerhog Enthusiast

Towerhog

Posted
Posted

I had a shudder in the truck when under a slight load (slight uphill), and the RPM's would fluctuate at that time.

 

The dealer replaced the torque converter and fluid. No more shudder and it drives smooth.

Billy346 Enthusiast

Billy346

Posted
Posted

I noticed my truck doing the same thing when I bought it. RPM's would fluctuate when the transmission was in a higher gear with the engine in a low RPM and under load. (Also called "lugging")

 

I did some research and found out that this is normal for GM trucks. The torque converter unlocks momentarily, causing RPM's to rise, sending more power to the rear wheels. The torque converter then continues locking and unlocking, causing RPM's to fluctuate until speed increases, you let off the gas, or the transmission downshifts. It does this to avoid downshifting while lugging. I'll admit that I thought it was a little strange the first time I noticed it.

 

My last truck was a Ford F-150, which behaved differently. Instead of the RPM's fluctuating, the transmission would downshift at the slightest increase of pedal pressure when going uphill. It had a 4 speed transmission, so when it would downshift, it really downshifted. I'll admit, I find the RPM fluctuation in my Chevy less annoying than the overly sensitive transmission in my Ford.

lba0213 Enthusiast

lba0213

Posted
Posted

Mine is no slight sudder, the steering wheel shakes hard enough to jingle my keys. Feels like going over rumble strips. Ive had the converter replaced but it fixed nothing. Theres always a chance the tranny tech, did a poor job though.

MrNasty Enthusiast

MrNasty

Posted
  • Author
Posted

So far I dont feel anything in the truck. I only started to notice it because the exhaust I installed you can hear the exhaust note change. So then i started watching the tach and speedo to see if something was wrong. Once you level the speed and are cruising the tach starts to bounce up and down. Just slightly but you can see it. I will try to shoot a short video tomorrow and see if I can post it. I tried with AFM on and with it off and does the same thing. I have an appointment to take the truck in on Saturday so I will see what the dealer tells me. I have read posts from people with more serious issues than mine and there dealer tells them its normal, so Im not getting my hopes up.

 

 

Sent from my iPhone using Tapatalk Pro

mookdoc6 Senior Enthusiast

mookdoc6

Posted
Posted

I noticed my truck doing the same thing when I bought it. RPM's would fluctuate when the transmission was in a higher gear with the engine in a low RPM and under load. (Also called "lugging")

 

I did some research and found out that this is normal for GM trucks. The torque converter unlocks momentarily, causing RPM's to rise, sending more power to the rear wheels. The torque converter then continues locking and unlocking, causing RPM's to fluctuate until speed increases, you let off the gas, or the transmission downshifts. It does this to avoid downshifting while lugging. I'll admit that I thought it was a little strange the first time I noticed it.

 

My last truck was a Ford F-150, which behaved differently. Instead of the RPM's fluctuating, the transmission would downshift at the slightest increase of pedal pressure when going uphill. It had a 4 speed transmission, so when it would downshift, it really downshifted. I'll admit, I find the RPM fluctuation in my Chevy less annoying than the overly sensitive transmission in my Ford.

Ok, this makes sense I would have to agree. Look at the new 6speed in Tacoma's compared to the previous 5speed. Owners are furious that you put it in Cruise mode and the slightest incline sensed and bamn back a gear! I do remember the Fords doing it now and I will take the RPM fluctuations if it keeps me from hunting gears!

MrNasty Enthusiast

MrNasty

Posted
  • Author
Posted

https://vimeo.com/190696634

 

The first big rpm jump is when it shifts into 8th gear. Then you can see the needle start bouncing. Its better or worse at certain speeds.

 

 

Sent from my iPhone using Tapatalk Pro

15_silverado Enthusiast

15_silverado

Posted
Posted

I've seen my 2017 6 speed do the same thing. No shudder or noises; rides smooth, but I have seen the needle bounce exactly like yours in high gear (6th gear) at low rpm at constant light throttle.

I'm assuming it's normal, but please let us know what you find out from the dealer or anywhere else. Thanks.

MrNasty Enthusiast

MrNasty

Posted
  • Author
Posted

Perhaps it's the torque converter locking / unlocking.

Thats what another member said and hopefully thats all it is. Just want to make sure because I'm about to be in West Texas with my wife and there isn't any help for miles. I will post what the dealer tells me this Saturday.

 

 

Sent from my iPhone using Tapatalk Pro

  • 4 weeks later...
Brandon5799 Enthusiast

Brandon5799

Posted
Posted

I'm going through the same issue now, dealer performed a service bulletin to flush the system and it still does the shuddering in 8th gear. I've noticed lots of guys lately have had similar issues around 10-15k miles. Everyone who's had the torque converter replaced has fixed the issue so mines going back into the shop for that next.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.6k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,993
    Total Members
    8,960
    Most Online
    President Roberto
    Newest Member
    President Roberto
    Joined

  • Who's Online   0 Members, 0 Anonymous, 238 Guests (See full list)

    • There are no registered users currently online

  • Latest Articles

  • Posts

    • bwiese
      upgrading speakers on 2026 std cab WT...

      By bwiese · Posted

      I don't wanna do major surgery/upgrades, behind-the-dash work, add amps, change radio etc. on my '26 std cab WT. On the WT, it has the base 7" IOR infotainment setup, and only two speakers (doors). Since I listen to classical, looked around for speakers that do well and dug thru reviews. Two-way speakers were found to be better than 3-way. So I've ordered a pair of  Infinity Reference REF-9632IX 2 way speakers.  [These may  or may not have been discontinued / succeeded by the 3-way ...9633 ones.]    These speakers are lauded for 3 ohm and 94db sensitivity spec so they'll work well for ordinary base car radios without amps and offer better performance (quality,  strength) than  default base paper-cone speakers. They'll be installed in a few days and I'll let y'all know what I think. Bill W San Jose      
    • RyanbabZ71
      RyanbabZ71's 2019 High Country

      By RyanbabZ71 · Posted

      Thanks!   Changed out the rear shocks today to Bilstein 5100s.  So far feel much better. The stock Rancho were wore out.  Lots of heavy hauling (2 moves, home renovations, etc).  Next up is new BFG tires Monday.  Cant wait the current tires have little to no wet traction and are super loud (hum)    
    • Snowcamo
      No high speed fans...

      By Snowcamo · Posted

      Ok, I got the all the codes. What do you all think would be a place to start?
    • Chuck FB
      Correct way to service 2024 l8t allison trans?

      By Chuck FB · Posted

      How about I just point to the factory pans stand pipe little drain plug and claim its a pan with a real drain plug !. I just couldn't swallow the fact that a Dorman pan which at this point is probably the only pan out there that fits the gas version truck cost that much up here in Canada so I decided initially anyway to skip it and see what I thought of pulling the pan method and down the road if I felt inclined enough then I would either install a drain plug kit in the factory pan if there is enough room for it, or have a bung welded onto it, or put an aftermarket pan on. The thing is if the pan is not pulled then the magnets in the pan can't be inspected and cleaned or if wanting to change out the filter. However of course it certainly would make the job easier to be able to drop the oil first before having to handle the pan if dropping the pan that go around was the goal.    I knew a guy locally that was doing custom field spraying years ago with a pickup pulling a ground driven sprayer, I believe it was a GM pickup with an automatic trans. He had a drain plug in his pan and would drop the oil out of it once a week and top it back up through the dipstick tube to keep refreshing a portion of the oil often and that made the transmission last far longer than had he done nothing. Soft fields pulling 500 gallons of water at the start of each mixed up sprayer tank batch and in low range sucking along. I imagine he got some tips from other custom sprayer outfits doing the same thing at the time and learning from their blown up tranny mistakes. Transmissions then had no lock up converter so would cook the crap out of the fluid slipping that much and it would not have been synthetic fluid either. 
    • KARNUT
      Gas Prices

      By KARNUT · Posted

      3.39 Kroger’s in Montgomery Texas. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...