Shaking / vibration, 4.3 in V4 mode

Darel Matthews · July 12, 2021

2014 LT Z71 with 4.3.

When the cylinder deactivation kicks in and the truck switches into V4 mode, it has a very noticeable vibration or shake. Not unlike driving on a washboard road. This is not a wheel balance / driveline issue, it's definitely when the cylinders are deactivated and it's pretty much like a light switch. Anytime, any speed, the truck is in V4 it's shaking. ENgine is totally smooth in V6 mode with all cylinders firing.

I know I got the crap motor, but did Chevy really do this poor of a job balancing in the V6 (and therefore this vibration is normal) or is something wrong?

I did search pretty extensively and can't find ANY reference to this, which I thought was really odd. If it was normal I'm sure I would have read a ton about it, or at least found one or two people whose engines grenaded right after this.

DIsclaimer: I "inherited" the truck from my dad, who swears it never had any vibration, but I felt it driving the truck home from his house for the first time. My dad also doesn't know how to put gas in his own car, and is the sort of person who goes into a dealership and says, "I would like one car, please."

Thanks,

Darel

Edited July 12, 2021 by Darel Matthews
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Grumpy Bear · July 13, 2021

I own a 2015 4.3 V6. Has 144,003 miles on it. Flawless miles. AFM works seamlessly. Gets great gas mileage. In point of fact everything works perfectly. Still on original brakes. First set of tires lasted 125,000 miles... only two sets of wipers. A $5 pinion seal and a $15 starter shield. That's my entire seven years of abnormal maintenance.

Unless a deer or a distracted driver takes her out.....solid as a rock and lov'n it.

Edited July 13, 2021 by Grumpy Bear

Darel Matthews · July 13, 2021

Uh-oh. Any ideas where I should start to look for the source of the vibration? The cylinder deactivation on my '07 is like yours, invisible and seamless, but that's the 5.3 and I thought maybe the inherent balance was different. Thanks.

Darel Matthews · July 13, 2021

OK, oddly enough I found a few references to guys with similar issues. To provide some more info if anyone's experienced this, the shaking occurs the entire time the truck is running in V4 mode, NOT as it transitions in and out of it (as most of the other guys seem to have indicated). The entire time the truck is in V4 mode, it feels like it's driving on a washboard road at all speeds and under all driving conditions. V6 ins perfect.

Also seeing a couple of references to GM firing the parts cannon at this. So it's not unknown, but it also doesn't sound like in seven years there's a confirmed fix?

Also please don't suggest one of those chips that eliminates the V4 mode. That's a bandaid, not a fix. You're just hiding the problem then. Also I love the gas mileage this truck gets, I'm comfortably getting 21 mpg and loving it.