2011 Silverado 5.3 question

[dukemason]

Hello

I've got a new Silverado with the 5.3 engine. It uses active fuel management, which allows the motor to operate on 4 cylinders when little power is required. Anyway, I noticed when driving around town I would get a ringing or ticking sound between 20 and 30 mph. It's loud enough that someone on the sidewalk could hear it when driving by. I started watching the AFM status screen and the noise is occurring when it's in 4 cylinder mode and a little throttle is applied. Once it switches to 8 cylinder the noise is gone. The service manager at the dealer tries to say it's exhaust noise from the 4 cylinder mode. I told him in no way does it sound like exhaust, unless it's an exhaust rattle. So to anyone that has knowledge of the 5.3 GM AFM engine, is this ringing expected behavior? Any help is much appreciated.

Thanks

 

[Chris142]

Maybe a heat shield rattling ?

 

[Lead Shoes]

My guess is heat shield rattle..

 

[Colt45ws]

I agree with the idea above probably slightly more vibration; or the vibration is at the correct frequency to set something off.

 

[justinf89]

Ask to hear another to see if it does the same thing. If not, then tell them to fix yours or give you a new truck. I bet they don't all do it.

 

[dukemason]

The service manager said they checked the exhaust for anything loose. I'll have to crawl under there and check myself. I'm about 99% certain this isn't normal.

 

[tomcat27]

just test drive one. at that dealer or another dealer.

 

[dukemason]

Yeah, I'll have to try another truck on the lot. No problem from them letting me drive whatever they got. I just didn't have time today.

 

[bigmike]

Based upon my experiences with my Silverado, it takes about 2 years to work out all the noises. Mine went in the shop several times for various things, all fixed under warranty. Some things were simple, like tightening shock mounts, body insulators, greasing caliper slides, etc. that I did myself to reduce the clunks, rattles, etc. Others I couldn't track down, so they put microphone chassis ears on it and narrowed down the noises.

 

[Rhymingmechanic]

Could it be a ping, as in preignition/spark knock?

 

[Steve S]

Sounds like you should have bought a Ford.

 

[NYEngineer]

I have an 09 Suburban, but I've never noticed any sounds like that. I'll try driving alongside some buildings with the window open and see if I hear anything.

 

[Stewart Fan]

My '07 Tahoe had AFM. It was absolutely seamless. Unless you were watching the DIC,you couldn't tell if it was running on 4/8 cylinders.

I'm pretty anal about noises my vehicles shouldn't be making.I'm always listening. I never heard anything from the AFM in 90K miles.

Something isn't right with yours.

 

[mechtech2]

Ringing and ticking are two totally separate noises.
Hard to diagnose which one [if either is correct] is happening.

 

[lexus114]

Originally Posted By: Steve S
Sounds like you should have bought a Ford.

He wants to get to where he`s going.

 

[UNC017]

Originally Posted By: dukemason
Hello

The service manager at the dealer tries to say it's exhaust noise from the 4 cylinder mode. I told him in no way does it sound like exhaust, unless it's an exhaust rattle.


From the way you describe it, I'll bet he's right- its the exhaust system "ringing" to the individual exhaust pulses in 4-cylinder mode. Basically each blast of exhaust makes the metal plumbing ring like a bell- sounds like a click followed by a metalling ringing. New exhaust systems make it more noticeable- as some carbon builds up inside the plumbing it will tend to damp that sound.

 

[dukemason]

Thanks for the responses. I'll test drive one from the lot and see what happens.

 

[MrCritical]

Heard several similar comments. Don't know if "all of them do it".