My 2009 Chevy Silverado is equipped with a 5.3 V-8 with active fuel management. What is active fuel management? Is this the system used by GM that shuts down cylinders to improve fuel milage. Also what is a general opinion of the reliability of the 5.3 V-8.
As noted above, AFM shuts down cylinders to save gas. However, it does cause issues.
The 5.3L V8 was notorious for lifter issues and camshaft problems. My father's 2013 GMC Sierra needed a new cam at 38k miles. And all they could replace the bad part with was the same parts that were destined to fail as well.
@mod_man
How does turning off spark and injectors for 4 cylinders cause issues? It only does this when the car is coasting (foot off the gas), so no extra strain is being put on the other 4 cylinders that are running.
@razmigb
No detonation = no heat would be my guess. Engine parts expand when they heat up and tolerances close up.
Anyway they burned a lot of oil.
@mod_man
what is the cause of the lifter issue?
It causes issues because while those cylinders are deactivated they are not receiving proper lubrication. This causes issues with heat and piston rings, which causes major problems. The issues are widespread so if you would like to know more details on the topic a Google search will help you with all the reading material you would like. As for the lifter issue cause, it is typically due to that oil pressure fluctuation. Here is a link to the technical bulletin on it. It is from Melling Engines regarding the issue:
It's just a case of bad design. Typical GM.
@mod_man
thanks. I have a 2013 5.3L LMF engine. Thankfully no AFM. Just VVT.
@mod_man
My bro has AFM in his Silverado. He said he deactivated when it was new.
VVT had few to no problems....just that AFM system they never got dialed in. Trying to engineer a fix was the bane of my 10 year career with GM. In the end there never was a solution. Your bro was smart to deactivate it. GM will void your engine warranty for doing that though. But honestly, without the AFM the engine design is pretty darn reliable.
@mod_man
his Silverado is 2014 so it's out of warranty by now anyway. I don't know what's involved in the delete, but if it could be reversed, then maybe GM would be none the wiser?
I believe the bandaid fix was a piece of metal that deflected the oil jets away from the pistons right? So you engineered engines for GM?
Usually guys delete AFM with a tuner, which of course can be seen in the software. However, the smarter way was yes the a metal piece that deflected the oil. Really not the best case scenario but it worked and it was better than just doing nothing and if the truck is out of warranty anyway, what the heck. I did engineer engines for them from the 2006 - 2016 period. So I got to see the implementation of those AFM systems unfortunately.
@mod_man
excellent. Now I have someone to blame for my engine problems hehe. 😉
Yeah yeah you won't be the first. {black}:nonoise: {black}:laughingoutloud:
Yes AFM shuts down half the cyclinders.
The V8 GM small block is a tried and tested engine. Been around forever. But I think the AFM is problematic. Some people get lifter noise but it's not serious.
@mountainmanjoe
AFMis problematic. It definitely wears out the engine faster.
GM's cylinder deactivation was much better than failed engineering Honda's VCM system.
Anything that is suppose to be running all the time naturally should be running, not intermittently turned off. That's where issues rise.
Just Keep your Trans in M5 or L5 and it won't go into AFM. On the interstate I would put in M6 or L6 unless you know your going for a trip and just put it in D
Free answer 🙂
