All about the C7 Corvette AFM and why its a problem

[Music] Hello everybody welcome back to c s Corvettes in Sunny Sarasota Florida this is your Corvette buddy Lyle here to talk to you about more interesting and exciting Corvette information today I'm going to cover a topic that I've gotten a lot of requests for regarding a particular problem with the C7 Corvette but before we get to that please take the time to like subscribe share do whatever you can but pushing those little buttons under our video to help our Channel we do this for free we are not paid by anybody to do this this is something we do out of our own pocket for you guys to help the Corvette hobby so when you can buy products from us we truly appreciate it but even if you don't need products or you just want to enjoy the content if you can like And subscribe that really helps us continue to do more and grow the channel for you so thank you in advance foreign guys deals specifically with C7 Corvettes and it probably applies as well to the C8 but I'm just dealing with the c7s today so I have been asked by several of our followers and our subscribers online to address the C7 Corvette AFM or active fuel management problems as it's not something we deal with a great deal here because we don't do deep engine work at our shop that's one of the few things we don't do with Corvettes here I had to actually do a deep dive and do a couple of days worth of research to be able to talk intelligently enough about this issue and how the system works to help you understand it so you can be more educated about the potential problems of the AFM system in your C7 here's a few of the basics I can share with you all c7s had the AFM system on them except for the ZR1 so if you're one of the few lucky people who owns a C7 ZR1 you don't need to worry about this problem at all because that car was so powerful they were like yeah I don't think we're going to need to worry about fuel mileage on this one might right so the AFM system was meant to provide better fuel mileage and at the even at the highest estimates this system provided a five to seven percent Improvement in fuel economy when the system was active well Lyle what do you mean by when the system was active how does that work well I'll tell you so normally your Corvette engine is running on all eight cylinders you got the great Rumble you got the great power with the C7 they decided to go back to an idea that they tried back in the 80s on The Cadillacs we called the 864 system better known as the 86 none system because it never worked really well basically it is deactivating four of the eight cylinders under a light load so if you're just putting along you know on on city streets going 35 miles an hour the system is going to activate and through a series of solenoids and oil routings to certain lifters on certain cylinders it basically just shuts down for the cylinders and your car becomes a V4 for all intents and purposes until you tip into the gas pedal and ask for more power at which point the system shifts off and you get back to full V8 power so let me explain a couple of the things about this um oh by the way the only time you have to deal with this in a C7 with a stick shift is if you actually put the car into economy mode other than that AFM doesn't enter into it when you got a stick shift car so among all the other problems they had with the automatic c7s especially in high performance situations having a stick shift once again seems to be the best option on a C7 for long term lack of problems the only time you can turn the system off in an automatic car is when you're in full automatic paddle shift mode other than that this AFM system is going to be intruding on your driving no matter what you do unless you're always using only the paddles to shift the car and the car won't shift without your input this is a big enough problem that in 2021 there was a class action lawsuit filed against GM across several of its Brands because they installed this system on virtually every V8 they made and it is becoming a much larger much more prevalent problem as these cars age and I haven't seen how that's going to turn out yet but it is I mean that's how big of a problem this is there's a class action lawsuit on it the two recommendations are if you want to not have this problem you can do one of two things you can buy a AFM disabler a company called range r-a-n-g-e makes a disabler make a couple different versions of it actually that plugs in directly to your little OBD2 port under the left side of your dash and that will basically keep your car from ever going into the fuel saving economy mode it basically just kind of like the simulators on the f55 shocks that I've talked to you about before that just tell the system no it's all fine same thing it just doesn't allow the car to go into it those cost a couple hundred bucks they're easily removable they don't affect your warranty they don't affect any other performance they're a very very good temporary solution so that you're not constantly dipping into V4 mode Honestly though what all of the experts recommend including places like Lingenfelter is for the long-term healthier car they recommend deleting the system completely and there are kits that are made for that and we're going to get into that in just a second but let me go into first how the system actually works the so in your head I've got some pictures that'll come up on the screen you can kind of figure out how this system does what it does so the three main components of the AFM system are the following you've got the Loma or lifter oil management assembly which is basically the flat plate that lives between the two cylinder heads in that Valley and kind of in the middle of the V of the V8 now in a normal LS engine or LT engine that is a smooth blank plate in this system there's actually four solenoids and a bunch of ribbing and an electrical plug on this plate those solenoids control the special lifters that are involved with cylinders one four six and seven all opposite in the firing order what happens with these is oh don't forget the block also has AFM Towers cast into it for these to Mo to mount to there's pictures of all this stuff that I'm sure Alan has put up for you to see so when Engine load is low here's how this system works the computer sends a signal to the lifter oil management assembly or what we call the Loma the Loma the four solenoids under the Loma open up and that allows oil to flow to the special lifters through the AFM towers that are cast into the block as the oil collapses the plungers inside those special lifters the collapse lifters will not engage the push rods and both valves remain closed so since no air can get in or out four cylinders provide absolutely no power and the engine is running on only Fuller cylinders uh the cylinders as I said are opposite one another in the firing order in four-cylinder mode they act like air Springs this allows for a smooth operation now when you tip back into the throttle the Loma sends a the computer sends a signal to the Loma the solenoids close oil bleeds off the lifters and as the oil bleeds off the lifters they begin to start moving again and they return to normal operation and then now all eight cylinders are functioning correctly again at least in theory right um the problem is and you've probably read about this or heard about it from other people online or whatever the AFM lifters themselves have a history of failing and killing engines oil consumption has also been a real problem and it's bad for performance in fact every performance article I read recommends if you're ever going to do any upgrades to your engine or updates to your engine in your C7 that you eliminate the system completely now when we talk about eliminating the system there's a couple different options and I'm going to cover those right now all right so basically you have two options when it comes to disabling or completely removing the AFM system I've already mentioned the most basic one of them which is installing one of those little range modules in your OBD2 port that will it keeps the systems from switching over to four-cylinder mode it's a simple effective way to turn off the system it's easily you can take it off and remove it and throw in your glove box and if you want to go back to AFM mode you can it also improves the sound of the exhaust when it's engaged because you're going to have full V8 sound all the time thank you here's the thing when you're using a disabler you can't disable or unplug any of the solenoids in the FM system and leave everything as it is all you do is plugs in that disabler because if you start going in and saying oh well I'm only going to use the disabler I'm going to take that Loma off the center of the engine unplug those solenoids well the problem is what you've just done is now since the car computer can no longer see those solenoids it turns your car into a full-time four-cylinder car which is really not what you want so if you're going to use one of the range modules don't worry about touching the engine just plug it into the OBD2 and be done with it and drive without it long term however basically everybody recommends and what they call an AFM delete kit now an AFM delete kit is recommended when an AFM lifter fails or when doing performance upgrades it replaces the AFM components with standard parts uh when you install an AFM delete kit there are several things you also have to do you have to move to a non-afm camshaft which is obviously no small task you've got to turn off the AFM system using a computer programmer like a Tech 2 or a laptop that is set up to do this or have it tuned out to where the car doesn't even see that as an option anymore it's also recommended that you plug the pressure relief valve in the oil pan and replace the high volume oil pump that AFM engines have with a standard volume oil pump why because if you don't do those two things and you leave the high volume oil pump in there it is going the high pressure oil is going to continue to squirt through the pressure relief valve into the oil pan and it's going to be splashing up on the bottom of your cylinder walls which will cause you to burn oil and over time can do damage to your engine so when you're in there I mean this is this is no small thing guys you're not you know we're talking head gaskets you're talking uh possible timing chain cover all these different things I looked at what some of these AFM delete kits run anywhere from about 550 to 950. I looked at several of them on Summit Lingenfelter makes one at like 750 doesn't include the camshaft and it doesn't include the oil pump that I saw but everything else that you need to do the job the replacement lifters the plate all of that's included in there so if you're going to do this talk to whoever's doing the tuning or the upgrading on your car because I'm sure this isn't their first rodeo with this system and how to delete it talk to them and what their suggestions are I'm just going by what I have found online and from sources that I trust so that pretty much does it for the AFM system guys it's not something that any of us in the performance World wanted it is something that GM did to appease the government and I don't know that it's ever going to be something that we look back on with any fondness thankfully there are simple ways to eliminate the function of it and even though it's not simple there are ways to completely eliminate the system for the long-term health and especially for high performance use uh survivability of your engine I hope you found this information useful I learned a lot while I was doing this research if you have questions or comments about your experience with the AFM system or if you've had it deleted and you want to add something to what we've been talking about please put it in the comments below we very much appreciate you watching have a great day [Music] thank you [Music]

Channel: C&S Corvettes

Views: 39,455

Keywords: Corvette, vette, C5, c6, repair, service, parts

Id: axjL4dl4cgo

Length: 13min 18sec (798 seconds)

Published: Fri Jul 07 2023