Rough idle- Vibration

scale obsession · September 21, 2018

At one point, I found an extensive thread, discussing the rough idle, and motor mount replacement situation. I'm unable to find it now. I'm been to two different dealers, PICO scope at both of them, and they claim its within acceptable range. Talked with GM care, they want a third opinion. If the third is within range, It sounds like I'm either going to have to make the decision to live with it, or trade the truck in, and move on, or purchase the motor mounts and install them myself. Are the motor mounts a definite fix for this issue?

Awwmann · September 21, 2018

No i had the motor mounts done in 2017 mine still vibrates . The only thing that stopped it for a few months for me was to run sea foam through the top end to clean the valves .

vinemann12 · September 21, 2018

With my 2016-RCSB / 5.3, I have rough idle at times (only with engine is cold) and when at operating temp,, zero idle issues @ 14K on odometer

Discussed with Dealership service manager, by buddy and they did PICO test with no findings...

He has seen a few 5.3's with this issue, 2015 and newer but no real definitive cause..

As I only use Top Tier gas,, mostly BP, not worried about crap gas or water in fuel.

I have seen that some folks replace plugs and wires and have success in eliminating idle problem but this could be placebo affect..

Cheers---K

20165.3Eco · September 21, 2018

I had the mounts done. It changed the idle in that it's less noticeable while in gear and more noticeable in neutral.

It'll shake your phone if you have your elbow on the console out of gear. Otherwise its fairly livable in gear.

scale obsession · September 22, 2018

Mine physically shakes the console, it’s super annoying. It only has 33k on it. It goes to the third dealer on Monday for a third picoscope, as requested by GM care.

scale obsession · September 26, 2018

Third dealership also says everything is within spec and operating as its designed. This is really frustrating. I'm not sure what the next move will be.

scale obsession · September 26, 2018

On 9/21/2018 at 11:50 AM, vinemann12 said:

With my 2016-RCSB / 5.3, I have rough idle at times (only with engine is cold) and when at operating temp,, zero idle issues @ 14K on odometer

Discussed with Dealership service manager, by buddy and they did PICO test with no findings...

He has seen a few 5.3's with this issue, 2015 and newer but no real definitive cause..

As I only use Top Tier gas,, mostly BP, not worried about crap gas or water in fuel.

I have seen that some folks replace plugs and wires and have success in eliminating idle problem but this could be placebo affect..

Cheers---K

Mine is more noticeable at operating temp, than anything. Top Tier gas here as well. Shell. I've seen similar posts as you , about plugs and wires and wondered if it really smoothed it out, or if it was placebo.