What Is This Engine Sound? Clip Attached!

084x4LTZ · July 4, 2009

Please tell us what this sound is?

I experienced this sound at start up since new, it almost stopped since I put fully synthetic oil 5w30, but returned after running about 5k miles. Out side temp. is about 96F..so it is not cold.

coldstart_13K_MILES_OT_96F_1.wmv

coldstart_13K_MILES_OT_96F_2.wmv

coldstart_AV_is_new.wmv

coldstart_13K_MILES_OT_96F_1.wmv

coldstart_13K_MILES_OT_96F_2.wmv

coldstart_AV_is_new.wmv

coldstart_13K_MILES_OT_96F_1.wmv

coldstart_13K_MILES_OT_96F_2.wmv

coldstart_AV_is_new.wmv

coldstart_13K_MILES_OT_96F_1.wmv

coldstart_13K_MILES_OT_96F_2.wmv

coldstart_AV_is_new.wmv

084x4LTZ · July 4, 2009

Engine= 5.3L, Flex+AFM

gave20 · July 4, 2009

Engine= 5.3L, Flex+AFM

there's your answer

084x4LTZ · July 4, 2009

Engine= 5.3L, Flex+AFM

there's your answer

Dealer refused to disable it....

Also, AFM is not active at idel?!

Many thanks & let's hear what others think

nbscanuck · July 4, 2009

Disabling doesn't fix it, its a hardware problem, lifters actually.

It won't activate at idle. I talked to a service manager and it has to do with cylinder temps. If did activate at idle and you gun it so it came off, there would be detonation issues in the cold cylinders.

Talk to you service department, they may not fix it, but get your concerns documented.

alwcurlz · July 4, 2009

Please tell us what this sound is?
I experienced this sound at start up since new, it almost stopped since I put fully synthetic oil 5w30, but returned after running about 5k miles. Out side temp. is about 96F..so it is not cold.

What is the truck, year, mileage?

alwcurlz · July 4, 2009

Engine= 5.3L, Flex+AFM

What does "Flex+AFM" mean ?

nbscanuck · July 4, 2009

Flex fuel

Active Fuel Management or Displacement on Demand

brims · July 5, 2009

Unless you're running over E10, then the FlexFuel designation doesn't really have anything to do with this whole thing.

084x4LTZ · July 5, 2009

Flex stands for Flexible Fuel which means you can use Ethanol or regular gas, not all engines come with Flex feature, I read it is only programming no special HW, and also read that injectors are different, I think it is a mix of all. .

AFM stands for Active Fuel Management which means engine will run 4 cylinders only when not on load

alwcurlz · July 5, 2009

Flex stands for Flexible Fuel which means you can use Ethanol or regular gas, not all engines come with Flex feature, I read it is only programming no special HW, and also read that injectors are different, I think it is a mix of all. .

AFM stands for Active Fuel Management which means engine will run 4 cylinders only when not on load

Not to get too off-topic but, what has the MPG been like with these trucks running on only 4 cylinders?

brims · July 5, 2009

Flex stands for Flexible Fuel which means you can use Ethanol or regular gas, not all engines come with Flex feature, I read it is only programming no special HW, and also read that injectors are different, I think it is a mix of all. .

AFM stands for Active Fuel Management which means engine will run 4 cylinders only when not on load

Not to get too off-topic but, what has the MPG been like with these trucks running on only 4 cylinders?

Same as running on 8.

alwcurlz · July 5, 2009

Flex stands for Flexible Fuel which means you can use Ethanol or regular gas, not all engines come with Flex feature, I read it is only programming no special HW, and also read that injectors are different, I think it is a mix of all. .

AFM stands for Active Fuel Management which means engine will run 4 cylinders only when not on load

Not to get too off-topic but, what has the MPG been like with these trucks running on only 4 cylinders?

Same as running on 8.

Wow, so it's a joke. Something to satisfy the global warming whackos I guess ?

brims · July 5, 2009

Flex stands for Flexible Fuel which means you can use Ethanol or regular gas, not all engines come with Flex feature, I read it is only programming no special HW, and also read that injectors are different, I think it is a mix of all. .

AFM stands for Active Fuel Management which means engine will run 4 cylinders only when not on load

Not to get too off-topic but, what has the MPG been like with these trucks running on only 4 cylinders?

Same as running on 8.

Wow, so it's a joke. Something to satisfy the global warming whackos I guess ?

Something like that, I've seen no difference since having Justin disable it. Nice idea, but it needs to stay off of trucks.