ocracokenc

I have never owned a GM product until the truck I have now. I needed a truck to tow my boat and it was a decent deal so I bought it. I have been reading a few people talking about issue's with the lifters with this era 5.3. I only use it to tow my Carolina Skiff 238 DLV on a tandem axle trailer. I am thinking about turning the AFM system off and would like some current feedback from people who have done so. I have noticed that when I am towing and it is going in and out of V-4 mode a lot that the torque converter seems to unlock and the transmission gets warmer from it but I may be wrong. The 5.3 tows really well but if I had to name a weakness it would be low end torque and I am thinking keeping it in V-8 mode all the time will help some.

I am also worried about the engine lasting. It had 109,000 when I bought it and has 119,000 now. I run Valvoline 5W-30 Synpower with a K&N oil filter and change it before 3,000 but who know how it was treated before me. I had thought about seeing if I could run the V.I.N number and get a GM history report. Thanks for the input

in2pro

The AFM will only go active if the system sees little load on the engine... the milisecond that the accelerator is pressed or the system senses load it goes to full 8...
Putting it in Tow Haul mode won;t stop the AFM from engaging but I have found that down shifting to "3" will prevent it... any towing is going to add heat to the engine and transmission, add a cooler if you have not already...

I have an 07 with the 5.3 AFM and just rolled over 90k, run M1 full synthetic and go by the OLMS which gives me about 7000-8000 miles between changes with a ACDelco oil filter...

Richard Till

i hate the AFM. i bought a programmer with the AFM delete. you`ll gain power and mileage too. thers also a little gadjet i see on some truck forums that plugs directly into the ALDL connector. i think i cost about $100. thats too much money for one function.

in2pro

I don't have enough information on the AFM failure to speak in depth but I will throw this out there anyway... simply disabling the AFM feature may not prevent it form failing... if the failure is caused by the 8 modified lifters involved in the AFM disabling them from going active may not change anything, they can still fail if its a wear or fatigue issue related to the lifter itself...

ocracokenc

in2pro, I like it when someone admits they don't know everything but they will give you a educated guess based on what they do know and say that it may or may not work. You sir are the type of people I listen to, Thanks

So from what your are saying it may not be the issue of the lifters starting and stopping and oil starvation issues associated with that but could just be a design problem that gets worse with use. If they get worse from use disabling the system could cause them to fail sooner because they do not get a break with it in V8 mode all the time. I think some people think the issue is actually the starting and stopping of the lifter and disabling the system fixes it. It seems to me that enough data has not been gathered to find the exact cause of issues when the do arise. It is kinda like having a blower motor that goes bad because it has a automatic sensor that changes it back and forth so people wire it to run one setting and it still goes bad because the blower motor is just bad no matter how you run it, Who knows.

I have decide to leave mine alone for now. I was hoping to help with some low end torque but my previous 2 trucks were Diesel and I just need to get accustomed to a engine needing to turn around 2800 rpm's to make power. With my other trucks anything over 2300 was just heat and noise and 1800 was the sweet spot but that is apple to oranges. Thanks for your time