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Rpm Fluctuate while driving

29K views 18 replies 14 participants last post by  Joshuaz-71 
#1 ·
Hello, i have an 09 sierra, 5.3L 4 speed. Lately I have been noticing that the rpms will surge between 100 and 200 when I am driving between 40 and 50mph. Has anyone else experienced this?
 
#5 ·
lzn197 said:
Could it be your Torque Converter Clutch releasing as yopu drive? Are you a left foot braker? If your left foot is barely touching the brake, it can cause this.
Is there an easy fix if the clutch is releasing at speed? I've been having similar issues with mine (4L80E)- RPM surge at 65 MPH+; seems like the TQ is unlocking. I checked the fluid level, and it was low, so now that I've got it right, the transmission is much better. I hope it's fixed now, but I'm not 100% sure.
 
#6 ·
Have had the same issue w v8 vortec 07 silverado w 4" lift for two years that I've owned it. Taken to dealership on three occasions. They hook it up to computer and issue clears up only to return a couple weeks later. Any ideas? Will issue lead to future, more serious problems. I love the truck but am getting ready to dump it.
 
#7 ·
Afd38,

I am truly sorry to learn that you are experiencing an issue with your vehicle and that it seems that the dealership cannot duplicate the issue. How you thought about getting a second opinion? I am happy to locate another dealership in your area and I could set up the appointment. Private message referencing this thread including your contact information, VIN, and current mileage if I can be of any assistance.

Regards,

Jennifer T.
GM Customer Care
 
#8 ·
Bigredchev said:
If your truck has afm the Rpms will increase 100-200 rpm when it goes I to 4 cyl mode. They will come back down when it goes back into 8 cyl mode
Its definitely this. And yes, mine gets worse when its cold too. An ECM reset helps for a while.
Annoying, but normal.

- EKinMN via AutoGuide.com App
 
#10 ·
mine does this too between 40 and 50 mph it almost sounds like a very very light slip and catch but i have no idea. Aftermarket exhuast made it more apparent.
 
#17 ·
I am having some of the same issues too. Here is some stats on the truck.. 2000 Z71 5.3 4x4 with 306k currently. While in park truck will idel fine no surging of RPMs. While driving at low and high speeds RPM's surge up and down. Usually only 200 maybe 400 and lasting 1 sec. to as much as 6 to 10 sec. I have read a good bit on here and some other sites. Here are some things I try unless told other wise. Solenoids in transmission and changing fuel and air filters I hope someone has had this, fixed it, and is willing to share it.
 
#18 ·
Not everybody in this thread has AFM, so there must be more going on here. If you have AFM, I am pretty sure you are experiencing the dreaded transition from 4 to 8 cyl and back again.

If you don't have AFM, then I'd look at cleaning the MAF and Throttle Body and resetting the ECM. If it's still doing it, you may want to start looking at the tranny.
 
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