Is there such thing as out of balance (engine, AC fan, etc.) that cause rough idle?

[smokey_mountain]

Blackbear guys were very helpful in analyzing the logs with me for the rough idle. They are A-class experts on GM motors and all analytics points that my ever persisting rough idle condition on 2018 Yukon is likely not ignition or fuel related thus no codes and very good reading in the logs.

Does anyone know if out of balance engine or out of balance AC fans condition is possible on 2018 engines?
Is there a fix for out of balance engine or AC fans? or any other engine fans?

 

[Doubeleive]

fans are electric, not attached to the engine.
things that could be out-of-balance - Harmonic Balancer, it could cause vibration but I don't know how you could determine if it is the problem or not, maybe @swathdiver ?

 

[mikeyss]

My next guess would be the harmonic balancer, I don't know how to prove it though. It's the next logical thing after everything you've already replaced or had checked. I also wonder if the crank or the flywheel may be out of balance due to missing weights.
I know mine isn't as new as yours, but I have a 09 Tahoe with a 6.2, and it usually idles smooth as glass, but there are some days it is a little rougher idling. I've seen your video in another thread, with the water bottle showing your rough idle, mine never gets that bad.

 

[OR VietVet]

Maybe the flex plate/flywheel. Maybe the harmonic balancer but typically they would get out of balance when the rubber dampener was coming apart on an OLDER vehicle, unless is just a bad new part. Maybe the torque converter. I have been involved with balancing engines before and I have never seen an out of balance crank but not saying it can't happen. Have you gotten the district rep involved from the dealership?

 

[smokey_mountain]

Yes, sadly gotten all the way to the Arbitration. General Motors of 2019-20 has their priorities wrong, instead of increasing Cost of Poor Quality budget to fight defects, they spend their money on lawyers and agents to fight with their customers. This is Mary Barra's strategy of customer care - drown your customers in legal paperwork instead of helping the customer to solve the issue, I guess it works, her approvals are still there.

Maybe the flex plate/flywheel. Maybe the harmonic balancer but typically they would get out of balance when the rubber dampener was coming apart on an OLDER vehicle, unless is just a bad new part. Maybe the torque converter. I have been involved with balancing engines before and I have never seen an out of balance crank but not saying it can't happen. Have you gotten the district rep involved from the dealership?

 

[smokey_mountain]

Yes, depreciation hit due to COVID on these trucks is so huge that I am considering options to pay for more troubleshooting, in the past 8 months since purchase truck lost $12K value and it is only with 5K miles added. Bottle test got even worse now. Thing is that I cannot find a shop in North Carolina who is willing to diagnose and fix. Everyone is afraid of these Gen V engines, even prominent performance shops are running away from DI engines.

My next guess would be the harmonic balancer, I don't know how to prove it though. It's the next logical thing after everything you've already replaced or had checked. I also wonder if the crank or the flywheel may be out of balance due to missing weights.
I know mine isn't as new as yours, but I have a 09 Tahoe with a 6.2, and it usually idles smooth as glass, but there are some days it is a little rougher idling. I've seen your video in another thread, with the water bottle showing your rough idle, mine never gets that bad.

 

[swathdiver]

fans are electric, not attached to the engine.
things that could be out-of-balance - Harmonic Balancer, it could cause vibration but I don't know how you could determine if it is the problem or not, maybe @swathdiver ?

On a car as new as his, see if it wobbles. Not the accessory drive that the belt rides on, which can wobble too, but the actual harmonic balancer.

For us, as our trucks get older, 10+ years or more it's a good preventive maintenance to replace them when the cracks in the rubber spread out and become more numerous. Good for engine longevity.

 

[smokey_mountain]

Thank you, I read a bit on the harmonic balancers and I still claim weak understanding but harmonic balance vibrations are felt as RPM increase and disappear in idle, can balancer still cause issues in idle?

On a car as new as his, see if it wobbles. Not the accessory drive that the belt rides on, which can wobble too, but the actual harmonic balancer.

For us, as our trucks get older, 10+ years or more it's a good preventive maintenance to replace them when the cracks in the rubber spread out and become more numerous. Good for engine longevity.

 

[Dantheman1540]

Does the vibration change with the ac on vs off? I have ridden in some older and one newer vehicle (2016 Chrysler 200) that the ac compressor clutch is going out or the load is to much for the engine to handle at idle so they begin to vibrate. The Chrysler was really bad. It didn't matter what gear the car was in either.

 

[swathdiver]

Thank you, I read a bit on the harmonic balancers and I still claim weak understanding but harmonic balance vibrations are felt as RPM increase and disappear in idle, can balancer still cause issues in idle?

Don't know enough about the topic to say yes for certain.