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

[smokey_mountain]

This is exactly what I have bit for bit... except mine is 2018 so many people have tried to fix it and all got the same "within spec" answer and learn to leave with it... that s a sad state of affairs with GM, https://www.gm-trucks.com/forums/topic/186851-rough-idle-when-coming-to-stop/page/7/#comments

 

[smokey_mountain]

I have changed MAP sensor with OEM AC Delco 12644228, no change with rough idle. I drove 500 miles today and through some really hilly terrain. After up the mountain driving if I come to a stop rough idle even at raised RPM of 650 is equally as bad as at 500. I have checked and both electrical radiator fans are spinning. I have tried to reach for the belt on Gen 5 engine and it is a crowded bay, I cannot reach the belt from the top to remove. Problem is that I have to remove the belt when engine is really hot, if water pump is disabled, I suspect I can overheat the engine but running hot engine without AC/pump on. On the Gen V has anyone did the compression test? I wonder if my one of my valves is slightly bent and compression is lost...

 

[Bob2C]

I have idle raised all the way to 650 now but skipping/miss is still there when engine is fully hot. It is a bit worse on Exxon 89 but my truck seems to like BP 89 or BJ's 93 best. This is not scientific at all, just what I feel. Throttle body clean seems to be the natural exploration but dealer would not do it under warranty of course and want $400 for the job...

Going to get BJs gas last week there is an Exxon station in the same shopping center. As I am coming up to Exxon the tanker truck pulls out and guess where the next stop is. Yep BJs. So at least this delivery was Exxon branded gas. I don’t know if it’s the same each time or they shop around. Been using BJs for years with no problems. Using now with 91/93 tune. Smooth no issues.


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[RST Dana]

Going to get BJs gas last week there is an Exxon station in the same shopping center. As I am coming up to Exxon the tanker truck pulls out and guess where the next stop is. Yep BJs. So at least this delivery was Exxon branded gas. I don’t know if it’s the same each time or they shop around. Been using BJs for years with no problems. Using now with 91/93 tune. Smooth no issues.


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Gas branding can be misleading. Trucks pull from tank farms and deliver to many different branded locations all the time. We used to deliver Chevron. It was the same fuel that was also delivered to mom and pops and other chains.

 

[Doubeleive]

the "dual fans" are the same for all packages, the max tow package which is rpo code "NHT" utilizes a thicker radiator of 1 1/8" the standard radiator is 7/8"
fans are all the same with brushless motors.

 

[sickk23]

You'll have a trailer brake controller if you have max tow.

I've followed this for a long time. My 18 burb has the same vibration. I just live with it because its a V8 and the rest of the vehicle is junk too so it doesn't really seem out of the norm. Tis no I6 I will tell you that.

 

[OR VietVet]

Every time I read about the problems with the newer rigs, from 2007 and up, I like my 2002 Tahoe even more. The biggest concerns are the engine vibes and the oil usage because of AFM and the noises. I drove the newer and the seats are uncomfortable to me as well.

 

[Bob2C]

Every time I read about the problems with the newer rigs, from 2007 and up, I like my 2002 Tahoe even more. The biggest concerns are the engine vibes and the oil usage because of AFM and the noises. I drove the newer and the seats are uncomfortable to me as well.

Agreed. I had a 2002 Yukon. Great vehicle. My brother still owns it. Only 80k miles. Runs like a top. Never had a major repair. Paint- meh. That’s another issue. Needs a paint job, but it’s 29 years old and he lives in New York.


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[mikeyss]

Every time I read about the problems with the newer rigs, from 2007 and up, I like my 2002 Tahoe even more. The biggest concerns are the engine vibes and the oil usage because of AFM and the noises. I drove the newer and the seats are uncomfortable to me as well.

I have an 06 Sierra and an 09 Tahoe LTZ. The 06 seats are WAY more comfier than the Tahoe, even the leather in the truck is softer, but the Tahoe has cooled seats. There's things the GMT800 did better than the GMT900, and vice versa. The torsion bar setup in the 800's suck bad in comparison to the 900's strut design. When I drive the 06, I instantly miss the VVT that my 09 has. The truck and Tahoe both have bose with Y91, but the Tahoe is better with a bigger sub and center speaker. The trucks interior feels like my living room, while the Tahoe feels like a lawyer's office. This is why I keep both generations, it's the best of both worlds.

 

[smokey_mountain]

I did extensive comparisons of nine brand new and five low-miles Yukons/Tahoes ranging 2018-2020. Here is what I found. It is roughly 50/50 smooth idle vs. rough idle. I feel that it is a GM quality control issue, no other explanation. Not every truck has rough idle at ~500RPM in gear at engine at operating temp, not at all, there absolutely smooth as glass trucks in 2018-20 lineups. I cannot agree that this is just a feature of 8-cylinders. What remains true is that after extensive trial and error, I cannot get idle to smooth out. Dealers did at my cost: mounts, plugs, wires, coils, swapped with GM Performance air filter. I have replaced the oil myself to ensure that fill is correct just under full, transmission was drained/refilled with ACDelco Dexron VI Full Synthetic and correctly filled just under full at 180 degrees. Tomorrow dealer is doing induction service again at my cost, they claim this is GM approved and recommended procedure for air induction.