see if you agree that came out in 2016 to 2019 in c7 ////cause I never want that crap in my Vette again so I'm looking for a 2014 or 2015

 

All C7s have AFM. That includes 2014 & 2015.
​​​​​​

 

ok didnt know that i had a 14 and a 15 and i never noticed but i bought a 17 and when it switched 4to8 you felt sluglish

 

2014s were notorious for having a rougher transition so I'm surprised you never noticed it. If you had the M7 transmission, AFM would only activate in Eco mode

 

So all this DOD/AFM is very new to me. Last vette was a '90 ZR-1, OBDI dark age stuff. I have a few Q's about the mechanical workings. Thanks in advance.
This is the system that uses lifter technology to stop the valves from moving?
Didn't GM & Chrysler have mechanical issues with this type of lifter technology?
Short of physically replacing the cam & lifters and whatever other parts needed that is the only way to avoid the mechanical failure of the DOD lifter?
Or I should just stop worrying about this as the C8 has a newer generation of the DOD/AFM system and I'm nucking futs.
I know I should have paid more attention. Truthfully, the C8 I now own just popped up on a Ford used lot as a local trade. One owner '21 w/4900 miles, Z51, 3LT, coupe. It was 70K, 75.5 all in, I could not pass it up.
Thanks again for any info thrown my way!

Tom

 

It deactivates cylinders 2,3,5 and 8. It does this by collapsing the lifters at exactly the right times, so that it captures, and holds a full combustion charge for the duration of the V4 mode. Both intake and exhaust valves are closed, and the deactivated cylinder act like springs.

It is disabled if the engine/shift is set to Track, or in manual shift mode.

The lifters are activated/deactivated by controlling oil pressure to those special lifters. Fuel injectors to the deactivated cylinders are turned off, but the ignition/spark is not turned off. The transition takes place in 250 msec according to the Service Manual. I think, though, that the transition time must be determined by the engine RPM. That is, because cylinder deactivation is timed so that the cylinder is on an intake event, it will be whatever time it takes for all four cylinders to experience an intake event.

 

Lots of folks get very excited about this topic, but shouldn't. No issues. Do you even know when it is going into V4 mode? I don't unless I see the light on.

 

The C8 hasnt had a lot of issues with AFM or lifter tick problems. The earlier LS engines (the C8 is a LT engine) had plenty of issues. With that said, I am a very fussy car guy and a auto tech. I feel and hear anything and everything. I am considering tuning out AFM because I hate it and the ECM in our cars can be unlocked so AFM can be tuned out. My good friend received his ordered 24 stingray about 3 months ago. he started hearing lifter tick when the car was under 1000 miles and it got louder a little at a time. He is also a retired automotive tech and he could tell he had a single tick on both banks. At 2000 miles it became pretty loud and he set up an appointment with the dealer. Turns out # 5 and # 8 which are 2 of the 4 cylinders that are deactivated for AFM were the problem. GM authorized all 16 lifters to be replaced. When the car was finished he put on 20 miles first day. He thought he heard a faint lifter tick, next day he had close to 100 miles on the car and the lifter ticks were loud. He spent time under the hood with the car idling and determined same 2 cylinders ticking loud. He is waiting now to get back into the dealer which will be the 13th. I lost what little faith I had with the very complicated (mechanically) never mind electronically V4 AFM system the provides nothing other than maybe a mile or two per gallon during very few actual situations. I personally do not like V4 kicking in or kicking out and if you are a mechanical guru car guy you will be aware of the nonsense of V4 mode.

 

I want to say thank you to Andy, BJ67, and tsigwing for your patience with the NOOOB.
tsigwing, you're correct. What little driving I did, about 13 miles, I couldn't tell anything driving on side roads. I didn't even notice if the light on the cluster came on or not. I think my cluster was in sport, but I'm not sure, I was in "auto" mode on the transmission. However, I'm in the camp of if it's mechanically complicated then there are simply more potential failure points. I'm not a fan of making things mechanically complicated unless you must.

BJ67 and I share the same dim view of overly complicated mechanical systems. Thank you BJ67 for your perspective, and that of your friend. Since I'm a second owner and the car is a 2021, and it's out of warranty so I'm on my own. I intend to spend the $650 that HelmInc.com wants to get an FSM. Hopefully I can learn something that will help me make a decision about potential courses of action if corrective action is needed.

Thank you all for your input on the subject!

Tom

 

You can pick my brain anytime Tom.

 

I see 4 possibilities here. Either your car is an amazing specimen or there's some noise insulation that works in your car but not in the ones that have all these noises or you are hearing impaired or you blast your music loud enough to cover up all these noises.

 

Actually none of the above. Never hear it or feel it change, nor do I hear any injector sounds. It really surprises me considering it is an American car and a GM at that!

 

Same here. I never hear anything although I can usually feel when it goes back to V8 mode due to the increase in power.

 

Or, for the vast majority of owners, it is a non issue. My wife is ultra sensitive to any perceived noise/issue. She has no clue when it goes into V4 mode.

 

I think I have the last two possibilities, but it doesn't seem to be a problem.