Vibration from somewhere under the truck

JOEWABELL

MEMBER
2008 GMC SIERRA
4.3L
6 CYL
2WD
AUTOMATIC
49,000 MILES

I have had a vibration, from somewhere under the truck, but it cannot be found. But I have noticed, that if I raise the idle to 1 on the rpm, the vibration goes away. My question, can the idle, on this truck be raise to one on the rpm, odometer? Now some may say it is factory set, and it maybe, but can a computer scan, or another way, raise the idle, of this truck to one. A mechanic told me once, they say things like this cannot be did but they can. Can you help?

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi,

Unfortunately, the idle RPM is set by the PCM so you would need to alter the PCM software in order to get the RPM to be changed.

As for the vibration, if it is felt during idle, does it only do it in Drive or does it do it in Park and Neutral as well? In other words, can you tell me all the ways the truck will make the vibration? Does it do it while driving? Accelerating or decelerating?

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Monday, August 26th, 2019 AT 1:18 PM

JOEWABELL

MEMBER
3 POSTS

When you come to a real slow stop, and while setting in drive I can hear the vibration, also idling in park. I can hear the vibration. The only time, that I do not hear the vibration, is when the idle is raised, to a 1 on the rpm. And held there. Thanks for your help.

Was this

answer

helpful?

Yes

No

Monday, August 26th, 2019 AT 2:32 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. You are saying that you hear the vibration but do you feel it as well? Normally, you hear a rattle or clicking but feel a vibration.

This may seem like semantics but I just want to make sure we are on the same page. Thanks

Was this

answer

helpful?

Yes

No

Tuesday, August 27th, 2019 AT 5:30 PM