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Pedal Vibration

nobrakes00

By nobrakes00
in Ask A GM Technician

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nobrakes00 Enthusiast

nobrakes00

Posted
Posted

Hi There!

 

I have a 2008 Silverado Ext Cab 5.3L with 8500 miles. I love my truck, but have noticed a slight pedal vibration in the accelerator pedal. It seems most pronounced between 50-60 mph, and is intermittant. Perhaps I'm just very sensitive as I had someone else drive it and they claimed they didn't notice a thing.

 

Any advice would be great.

grosss Enthusiast

grosss

Posted
Posted

Vibration in the accel pedal based on speed is usually a sign of an off balance tire (or 2, 3 or 4 tires!) if it's that slight and only at those speeds, the weight is off just slightly, and hits a bit of resonance at those speeds. No tire assembly machine in an assembly plant is perfect and the odd tire is a little off. If it really bothers you, take it to the dealership and ask them to check the balance on all of the tires for you. See if you can pinpoint the tire causing the issue (if it's one of the front tires, you might feel it in the steering wheel). If you feel like really digging deep you can rotate your spare tire with each of the wheels on the truck to see if you can find the culprit as well.

 

Another possibility is a little rust buildup on a brake rotor hitting the caliper, but it's more likely an off balance tire.

 

Overall if it's just a minor thing that doesn't really bother you, I wouldn't worry about it.

nobrakes00 Enthusiast

nobrakes00

Posted
  • Author
Posted
Vibration in the accel pedal based on speed is usually a sign of an off balance tire (or 2, 3 or 4 tires!) if it's that slight and only at those speeds, the weight is off just slightly, and hits a bit of resonance at those speeds. No tire assembly machine in an assembly plant is perfect and the odd tire is a little off. If it really bothers you, take it to the dealership and ask them to check the balance on all of the tires for you. See if you can pinpoint the tire causing the issue (if it's one of the front tires, you might feel it in the steering wheel). If you feel like really digging deep you can rotate your spare tire with each of the wheels on the truck to see if you can find the culprit as well.

 

Another possibility is a little rust buildup on a brake rotor hitting the caliper, but it's more likely an off balance tire.

 

Overall if it's just a minor thing that doesn't really bother you, I wouldn't worry about it.

Hey Thank You! I really appreciate your insight - sounds very logical.

GMTRUCKTECH Enthusiast

GMTRUCKTECH

Posted
Posted
Hi There!

 

I have a 2008 Silverado Ext Cab 5.3L with 8500 miles. I love my truck, but have noticed a slight pedal vibration in the accelerator pedal. It seems most pronounced between 50-60 mph, and is intermittant. Perhaps I'm just very sensitive as I had someone else drive it and they claimed they didn't notice a thing.

 

Any advice would be great.

here you go bud

6-06-05-001B: Information on LMG, LC9, LY5, LH6, L76 Change in Exhaust Tone or Sound for Active Fuel Management (AFM) System Equipped Engines in Four Cylinder Mode - (Feb 26, 2008)

 

 

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Subject:Information on LMG, LC9, LY5, LH6, L76 Change in Exhaust Tone or Sound For Active Fuel Management (AFM) System Equipped Engines in Four Cylinder Mode

 

 

 

 

Models:2007 Buick Rainier

 

 

2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe, TrailBlazer

 

 

2007-2008 GMC Envoy Denali, Sierra, Yukon, Yukon XL

 

 

2007-2008 Saab 9-7X

 

 

with Active Fuel Management System Vortec® GEN IV 5.3L or 6.0L V8 Engine (VINs 0, 3, J, M, Y -- RPOs LMG, LC9, LY5, LH6, L76)

 

 

 

 

This bulletin is being updated to include 2008 models. Please discard Corporate Bulletin Number 06-06-05-001A (Section 06 -- Engine/Propulsion System).

 

Some customers may comment on a change in the exhaust note or tone when an Active Fuel Management System equipped engine is in 4 cylinder mode. Some drivers may also notice a very slight vibration in either the accelerator pedal, floor pan and/or the steering wheel. This is a normal condition for Active Fuel Management System equipped vehicles and no repairs should be attempted.

 

<A href="http://gsi.xw.gm.com/si/showDoc.do?docSyskey=2072530&from=sm#ss1-2072530">

Customer Information on Active Fuel Management

When the Active Fuel Management System is enabled, physical changes take place within the engine that allow it to run as a 4 cylinder motor with accompanying additional fuel savings. The change in exhaust tone is expected as all sound from the exhaust is the result of combustion in the engine. The ability to perceive these changes in sound are kept to very minimal levels as the Active Fuel Management System is only activated during steady state/near steady state driving or during coast down. In both of these situations, the load on the engine is minimal and general exhaust volume (sound) is low. You may give a copy of this bulletin to your customer.

 

 

  • 3 weeks later...
nobrakes00 Enthusiast

nobrakes00

Posted
  • Author
Posted
nobrakes00 I have the same problem as you described. Did you do or try anything to fix the problem?

 

Sorry, I haven't logged in for a couple of weeks...

 

I took it to the dealer earlier this week to redeem a free oil change, and mentioned this issue to the service advisor, but he looked at me like I had asked the freakin' square root of something!

 

Btw... I usually change my oil and do minor mx myself, and sure enough, the tech must have checked my air filter too, and didn't screw it back in. Uggh! I'm going back tomorrow, so I'll check.

sce_blitz New Member

sce_blitz

Posted
Posted

ok...thanks nobrakes.....

I also noticed this vibration since I put Castrol Synthetic oil in. Before I noticed this vibration I was using the regular Castrol GTX.

I guess I could try and switch back it see if it goes away, but I'm tempting to bring the truck into the dealer.

Spurshot Senior Enthusiast

Spurshot

Posted
Posted

I have a 08 Vmax that does the same thing. First I thought it was the driveline, then I've come to the same conclusion as the bulletin above. It's the AFM cutting 4 cylinders out that causes this. Oil would not be a cause.

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