Chas1955

I have a 2007 NBS LTZ Silverado with the 6.0L & Super Duty trans. When ever I'm stopped at a light it's like someone bumped me in the rear. This seems to happen about 5-10 seconds after I stop. I've got 13000 miles & it has done this since new. I have the trailering max package & I believe it's just the trans reacting to the cam timming? Not worried just wondered if anyone else has this.

ZX1100F1

This is a normal operating characteristic that most people experience with the 4.8L, 5.3L and 6.0L engines.

RoflCopter726

I have an '07 5.3 and mine does the same. I was wondering about it also, but if its normal then no big deal. At least now you know you're not the only one.

cams 98 silverado

when this does it is your a/c on at all? i put too much a/c stuff in and it would turn on and off and made my rpm's jump and i thought i was bumped too. next time it happens just look at your rpms. or put it in neutral and watch.

ax7221

I had the same problem 10k miles ago, took it to the dealer, they said the drivershaft slip yolk needed more lube, ever since then its happened maybe twice.

ZX1100F1

There are two types of "bumps", one occurs as you launch (slip yoke) the other happens while you are sitting still at idle.

The intermittent surge (or bump) felt at idle may be induced by a catalyst monitoring diagnostic event. During the event the system calibration will drive the fuel system lean then rich very quickly. The test is done to monitor catalyst efficiency. This test can cause a noticeable bump or surge when the vehicle is at a stop (at idle), transmission in gear, and the brake applied.

Chas1955

I don't know my 99 5.7L , or my 2002 Tahoe 5.7L or my 2005 2500HD6.0L Never did it?

jlm6740

Chas, I have had the same problem. I thought I had been rear ended a couple of times. It was more pronounced during hard braking.Kind of like a pop or lurch.

I had the dealer lube the yoke on my truck and it solved most of the problem. Now I only notice it occasionally, and it isn't nearly as bad.

Chas1955

Nope no AC & I will talk to my chevy dealed akout the Yoke. I do know on my 2500HD I had a vibration & took it back 3 times before Chevy admitted they had a problem with some 2005'S? HD's with that problem. They had to do something to the rearend/driveshaft & it was alot better when I got it back. Chevy must let you complain before they fix it?

THANKS EVERYONE
Charlie

ax7221

I don't know, I never had a problem with a bump on launch, it was always 5-10 seconds after stopping (usually at a light) and thats what they ended up doing, after I explained it.