papageoff

I have this too. I cannot find any cause and it's annoying but so far, harmless.

If I remember the manual correctly it says you can change I to 4hi or 4auto at any speed. I do so all the time without issue. I don't always coast, but I'm not into the throttle either. Basically, just steady speed or off throttle and I've never had a problem. For 4lo, you have to be basically stopped or moving less than 1mph. The truck won't let you go into 4lo at anything faster. Sent from my SM-G892A using Tapatalk

Mine does this too and always has. I believe it's normal. You're just hearing the chain in the t-case when it's engaged because it's basically right under the center console area.

My '15 has about the same mileage and the older it gets the more concerned I am about it's longevity. It's already had to have the AFM lifters on one side replaced and the y-pipe with the cats replaced. Both done under various warranties. I'm rapidly approaching the end of my extended warranty and powertrain warranties. I'm afraid the days of the 25 year old chevy cruising around are nearing an end.

Who knows? Could be where we live (hotter climates) or how we drive or just about anything. Mine didn't do it all the time, but it did enough to concern me ... Especially since we were shopping for a camper. Sent from my SM-G892A using Tapatalk

I recently had 2 cylinder's AFM system replaced. I've noticed in the couple months since that my mileage seems to have gone down a bit. It seems to go in to 4cyl mode just as often as before, but when it does many times the MPG gauge doesn't move. Other times it bounces back and forth between 18 and 24 like a clock ticking. It didn't used to behave like this. I'm driving the same roads. Also, (and I believe unrelated) I had the cat coverter y-pipe replaced under warranty a couple weeks ago. At least one core was rattling. I first noticed it after the AFM repair, but it might have been doing it before... I'm not sure. I'm just curious is anyone else noticed anything like that when there's was fixed.

Mine used to creak a lot and rattle, too. Turned out to be one of my shocks up front was shot. Sent from my SM-G892A using Tapatalk

Neat. Merry Christmas. Sent from my SM-G892A using Tapatalk

Lol, I just realized this was my thread... So I guess you knew what I found. :-D Sent from my SM-G892A using Tapatalk

I had pinging for years on 87 and I finally broke down and did some testing by running 89 for a few tanks and then 91. The 87 helped, but the 91 eliminated it. A friend also pointed out that the 89 may not be as fresh (in general) as the others since fewer people probably buy that vs the other two. I don't like paying for it, but it did stop the knock. Sent from my SM-G892A using Tapatalk

Got the truck back yesterday. They said the screen and core of at least one cat we're loose and rattling. It was covered by the 8y/80kmile emissions warranty. Sent from my SM-G892A using Tapatalk

Got the truck back yesterday. They said the screen and core of at least one cat we're loose and rattling. It was covered by the 8y/80kmile emissions warranty. I was told it'd be about a $2000 job (at the dealer) had I been past the warranty period. I had 78,500+ when I rolled in. The truck seems fine and the mysterious exhaust rattle that appeared after my AFM repair is gone. I thought it was a heat shield, but turned out to be this. Sent from my SM-G892A using Tapatalk

I was told this afternoon that the converter has failed and will be replaced. There looks to be three on the diagram. I'm not sure if they mean all three or just one of them. It's going to be covered under the 80k emissions warranty. I got in just under the wire, thankfully. The truck has 78,500 miles. Sent from my SM-G892A using Tapatalk

That sounds like a failing cat to me. I'd take it in or at least talk to them. I just took mine in today for a p420 code which is supposed to be a failed cat but the truck seems fine, no smells. We'll see what they say. Sent from my SM-G892A using Tapatalk

Heh, I'd love to but it's my daily. My days of gutting cats and straight pipes went with my 5.0. ...God, I miss that car. Sent from my SM-G892A using Tapatalk