Beating a dead horse here...
Have a Denali 6.2 that I just purchased from CarMax (with an extended warranty/Thank God!)
Tapping sound from the start.
Ran two tanks of 91 octane to eliminate possible octane knock.
Took me past the 7 day return policy and 30 day standard warranty with CarMax. Didn't really bother me because of the factory warranty.
Truck looked brand new. Even had the wrapping on the DVD player.
Popped the hood and started looking for an exhaust leak. I found a donut/flange laying on the crossmember.
Took it to the dealership. Found that the truck had two new fuel injectors and a new Catalytic Converter. Someone was searching for the cause of the sound.
Dealership tightened some gaskets and said the truck was good to go.
It made the deafening tapping noise on the way home.
I returned the truck to the dealership. Even though I have purchased 4 vehicles from them in the past to include a current 2019 Arcadia -- they had no loaner for me.
They kept the vehicle for two more days. Could not find the cause of the noise.
I went back to speak with the service manager. He was not happy.
He went on a ride with me and heard the noise. Claimed it was the transmission searching for the proper gear.
Weird because the noise happens constantly -- to include start up and idle.
Told me his 6.2 made same noises and it was normal.
Finally took it back to CarMax. They sent it back to same dealer with a promise to pay for diagnostics.
Miraculously, dealer finds lifters to be the issue.
I'll keep updated on status of cam, etc.
I think I'll trade this lemon in on a diesel or anything without AFM.
Will also not be purchasing from Bob Howard GMC in Oklahoma City.
I have a 2017 Sierra with a 5.3. I have had free oil changes for the last two years and have used the dealer's supplied Dexos. My engine and transmission are working great. I have read that many people hare having issues with AFM and hard shifting trannies. I have use Amsiol signature in all my other vehicles. Has any one switched to Amsoil and experienced problems? I am wondering if I should leave well enough alone.
This may be a rather strange question, but is it possible to reset the learned driving habits? My 2014 GMC Sierra 1500 SLE 4x4 crew cab drove great for the the first year (new to about 10,000 miles). The truck was very responsive and the AFM was not bad then--it only kicked in at about 45 mph or greater and it was not objectionable. After about a year, the AFM started engaging much more aggressively and at lower speeds--the truck would periodically jerk violently when it entered V4 mode. It began trying hard to avoid downshifting, so there is absolutely no power when you turn corners or start up a hill unless you really shove down on the gas pedal. I distinctly remember a coworker saying, "What's wrong with this thing?!?" soon after the clunking and other stuff started. The dealer said it was learning my driving habits and everything was normal. Now, I have 57k miles on the truck and I really do not enjoy driving it anymore. I have about a 25 mile commute with long stretches of 35 mph speed zones. If I don't drive in M5 or activate the Range device, the truck repeatedly goes "CLUNK, lug, SQUEAK!" as the AFM engages, the truck lugs along for a bit, and goes back to V8 mode (with passive exhaust valve squeak, of course). I have noticed the clunking is much worse when the outside temperature is below about 45 degrees. The dealership says I am stuck with this behavior because it has adapted to my low-speed stretches and there is nothing I can do about it. They say most of their similar complaints come from people who drive at lower speeds.
The truck has only been maintained at the dealership--I got tired of them saying I was not maintaining my last truck properly (Mobil-1 changes at 4-5k miles or 45% oil monitor remaining, coolant and transmission flushes at 30-35k, and all fluids replaced at 50k miles, mind you). I have had them do far more maintenance than recommended and I don't hesitate to throw this fact back in their face when they start to say I have done something wrong to cause the bad behavior (they said going too long between oil changes probably caused it until I told them to check their records). They tried pulling the battery and it didn't help anything. I would love to have my truck drive the way it did when it was new. I know I could get a tune, but I have an 84 month, 84K mile warranty and I don't want to risk having too many increments of the flash counter. My dealer says to get a tune when the warranty expires, but I doubt I will keep the truck that long--I honestly don't have much faith that the drive train will hold together. The constant "clunk-lug-squeak!" reminds me of the clown cars you see at a circus. Does anyone know of a way to reset the learned behavior or do I have to live with it until I get rid of the truck? I can get access to SPS if there is a way to resolve this via the dealership tools. Any help would certainly be appreciated!
So I have recently purchased a Range AFM disabler for my 2017 Silverado 1500 E-assist because of the constant stopping and starting at stop lights, exhaust drone from V4, weird shifting from V4 to V8 and my transmission liking to jerk/shifting hard every so often.
After installing the Range device, it has solved my transmission issues, disabled stopping and starting at stop lights, and has been keeping it in V8 mode 24/7! The only thing I have noticed is that when I am decelerating from a speed of around 50 MPH or more, the engine will have a fast repetitive backfiring popping sound until i either get back on the gas pedal or have reached a speed of 35 MPH.
It seems to happen when i am decelerating slowly and not fast, starts to backfire when it starts to downshift at around 900-1100 RPMs
I have a flowmaster Super40 cat-back dual 2.5 inch exhaust with the third "cat" still on. It used to not backfire when the AFM was active BUT when decelerating, it would switch back into V4 mode. is there a way to fix this? Is there too much freeflowing exhaust? Can this backfiring through the exhaust cause any damage if left unfixed?
Recently Browsing 0 members
No registered users viewing this page.
Most OnlineNewest Member
Who's Online 92 Members, 0 Anonymous, 1,405 Guests (See full list)
- 07 VortecMax
- Billy A
- Sean Hartley
- Super 8
- RAYS B4U
- Race Neely
- Maize & Blue
- Skai R
- David solar