Rough idle on my low mileage 2021 tahoe

[Chickensandwich]

I had it looked at by the dealership. I was concerned about the rough idle. Being a fairly newer (to me) truck, I kinda felt it should idle pretty smooth. The truck doesnt shake, but sitting in the seat, I can the engine roughness. RPM at idle is pretty smooth at around 550-600. Maybe I’m not picking, maybe because of my other car which idles so smooth, you’d swear it’s electric, and it’s a 2007. With the whooshing sound of the fuel pump (so I’m told) and the rough idle, I’m concerned just a bit. The dealership says it’s all good, I’m guessing if they could take some money and adjust something, they would. Is this normal? 2021 Tahoe 35k on it, using premium high quality gas. I’ve run some Lucas fuel system cleaner through it, no change.

 

[viven44]

I'd hook up a scan tool and look for fuel trims, and spark plug misfires. If no misfires and fuel trim looks normal that's good.

Not sure what you mean by whooshing sound of the fuel pump ? I don't believe the fuel pump can be heard inside the cab.

 

[Micahsd]

When I had a ‘21, I don’t recall hearing the fuel pump either. If there’s no service engine soon light showing, it’s probably the usual rough idle that occurs when the fuel management is active.

Both the 5.3 engines in my ‘21 Tahoe and my current ‘25 Sierra have a bit of a rough idle that you can feel when sitting parked idling. If that’s all it is where it feel a slightly rough and you don’t hear it missing or struggling to run, it’s probably the normal engine feel that I’ve encountered.

Aside from the lifters at 9k miles, I had really no other engine issues my with ‘21 and traded it off at 43k miles. I always turned off the auto start/stop every time I got in it which I suspect may have helped keep it from having the fuel delivery/fuel pump module issues that I’ve heard a lot of with the ‘21’s.

 

[K5-Z71]

I’m no expert on these trucks but I imagine you couldn’t hear the fuel pump unless it’s about to fail. If I’m not mistaken the fuel pump primes each time the keys near the vehicle. Does it make strange noises you can hear from outside the vehicle? Does the swooshing increase with RPM?

Check your fuel additive to ensure it has PEA and you are using it at the right concentration in the tank. My 22 5.3 is typically silky smooth but when I feel some vibration at idle I’ll dose it with Techron which will smooth it out till next oil change.

 

[jerry455]

My 2021 6.2 Suburban has 87,000 miles and I have had it for just over one year. The 2 times I have a had a rough idle, I used Techron and it smotthed it out. I have used Techron for many years and I have had good results. I have never heard the fuel pump or any wooshing sounds. It runs great.

 

[Chickensandwich]

I can not hear the whooshing noise from the outside, only inside the cabin

 

[jerry455]

I have never heard that type of noise, maybe it is the HVAC ?

 

[Chickensandwich]

No HVAC was on. It sounds like a pulley scraping as a belt goes round. I don’t think that’s it, but that’s what it sounds like and that’s how it’s timed.

 

[K5-Z71]

Is the sound coming through the speakers, bad grounds and EMI can cause faint noises.

You said HVAC was of but was the AC compressor selected off?

Could be a restriction in the AC lines or coolant moving through the heater core.

There are little microphones you can tape to various places to isolate a noise like that.

 

[Vinnoto1]

I have about 36k on my 22 XL, I have experienced a rough idle bouncing around 500 rpm when stopping the vehicle. Brought it to the dealer a few times they cant find anything said its normal. Yesterday right after i got off the highway and came to a stop the whole engine and car shook and dropped rpms and then came back. Like it was trying to activate the AFM/DFM who knows? Heading to the dealer Friday for my recall check, hopefully they can find something.

 

[Chickensandwich]

Let me know what they find. I have the Range device to turn that AFM/DFM off. The start/stop isn’t a thing on my truck

 

[jfoj]

Techron Complete Fuel System Cleaner, follow instructions.

Check air filter.

Run vehicle in L9 as this pretty much disabled DFM.

 

[millers215]

I'm having the same issue with our 2020 Tahoe 6.2L. I know its an issue because the wife even brought it up . Shudders at idle even after driving for a while. I tried the two bottles of Techron and made sure to buy "name brand" 91 octane fuel. The shudder was gone until we went back to buying our regular, Costco 91 octane and then it returned.

Any ideas on what to do next?

 

[Chickensandwich]

I use Lucas cleaner and 93 octane. No change. All clean filters. GM said that’s normal for a a truck V8.

 

[millers215]

Interesting- my 2021 Silverado with the recalled 6.2 doesn't do it. Of course, it has its own list of potential issues now.

 

[blanchard7684]

I use Lucas cleaner and 93 octane. No change. All clean filters. GM said that’s normal for a a truck V8.

Not totally sure that Lucas uses the PEA additive that is in Techron. That is the substance that knocks off soot.

I’d also recommend a catch can.

 

[BacDoc]

Just like the motors seems like there’s a quality control issue. Most have no problems but some report noisy rough performance.

I have just over 11k miles and almost hate saying that my truck is smooth riding and quiet, shifting smoothly and no noise! Gotta be quality control as these trucks should all be the same.

 

[Chickensandwich]

Not totally sure that Lucas uses the PEA additive that is in Techron. That is the substance that knocks off soot.

I’d also recommend a catch can.

I was told that I can’t use a catch can and keep the warranty in place. Same with using thicker oil. Due to lifter issues, I need that warranty to stick around a bit