AFM lifter failure. Common?
Thread Starter
Le Mans Master
Joined: Mar 2016
Posts: 9,123
Likes: 3,975
From: 2019 CMG Z06
The following excerpt is from an article published by Super Chevy "Getting to Know the LT1 - Part 2:
The LT1’s Active Fuel Management (AFM) system uses ECM-controlled deactivation lifters to shut off cylinders 1, 7, 6, and 4, creating a virtual V-4 with an 8-2-5-3 firing order.
Dennis
The LT1’s Active Fuel Management (AFM) system uses ECM-controlled deactivation lifters to shut off cylinders 1, 7, 6, and 4, creating a virtual V-4 with an 8-2-5-3 firing order.
Dennis
Thread Starter
Le Mans Master
Joined: Mar 2016
Posts: 9,123
Likes: 3,975
From: 2019 CMG Z06
7200 on my 16 z51 drysump. 500 mile oil change in late 16, put the car away for the winter. I keep track of oil changes, do my own ever since the mandatory dealer 500 mile one. 4 oil changes in 6,700 miles since the 500 mile one. I check the level often, have never added a drop. About 9.25 quarts gets me exactly where I need to be on the dipstick. Always mobil1 full synthetic 5 30.
Melting Slicks
Joined: Jul 2018
Posts: 2,758
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From: Fort Wayne, IN
I believe the M7's don't go into AFM unless the car is in ECO Mode, so if you have a manual you can just avoid that setting. However; I think the OP has a manual... so would it really help if it's still happening when not using AFM
Race Director
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From: Supporting the Corvette Community at Abel Chevrolet in Rio Vista, CA 707-374-6317 Ext.123
St. Jude Donor '08
We do lifter replacements frequently, but not just on the C7. The lifters are the same in the trucks, SUVs. Camaros etc. It's more common for the AFM lifters to fail, but it doesn't have anything to do with how little or how often it's in 4 cyl mode. We've done AFM lifters in cars with range modules so contrary to what the forums continue to regurgitate, it won't prolong the life of your lifters (or your torque converter or...).
To clarify, AFM is cylinders #1 and #7 on the left bank and #4 and #6 on the right bank. Over the years we've seen failures on any of those cylinders so I wouldn't say that one is more common than the other.
To clarify, AFM is cylinders #1 and #7 on the left bank and #4 and #6 on the right bank. Over the years we've seen failures on any of those cylinders so I wouldn't say that one is more common than the other.
Drifting
Joined: Nov 2005
Posts: 1,668
Likes: 888
Would disabling the AFM with the Range device make any difference in these situations?
But maybe you dislike the name RANGE. Do you like the name Lingenfelter Performance Engineering. when associated with corvettes? They can make AFM go away for you cheaper than RANGE, WITH some sweat equity on your part:
https://www.enginelabs.com/news/tech...delete-afmdod/
But the best way is to get those wonky AFM lifters out of your car, period:
https://help.summitracing.com/app/an...ment-%28afm%29
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Team Owner
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From: I live my life by 2 rules. 1) Never share everything you know. 2)
St. Jude Donor '11-'12-'13, '16-'17-'18
The following excerpt is from an article published by Super Chevy "Getting to Know the LT1 - Part 2:
The LT1’s Active Fuel Management (AFM) system uses ECM-controlled deactivation lifters to shut off cylinders 1, 7, 6, and 4, creating a virtual V-4 with an 8-2-5-3 firing order.
Dennis
The LT1’s Active Fuel Management (AFM) system uses ECM-controlled deactivation lifters to shut off cylinders 1, 7, 6, and 4, creating a virtual V-4 with an 8-2-5-3 firing order.
Dennis
Thread Starter
Le Mans Master
Joined: Mar 2016
Posts: 9,123
Likes: 3,975
From: 2019 CMG Z06
Find a dealer mechanic you can trust and have them look at it. The less pronounced knocking/tapping is what got me. Mine never got anywhere as loud as the video posted on page 1, but it certainly is a noise that's not your normal lifter tick you hear on many v8s. Lucky for me, the check engine messages kicked on as the mechanic was already looking for the source.
Thread Starter
Le Mans Master
Joined: Mar 2016
Posts: 9,123
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From: 2019 CMG Z06
No clue. If my cam is scored, then even more parts and hours of labor. But I do know that my plans for a supercharger this winter are now scrapped. I still have 2 yrs of PT warranty remaining, and kissing that goodbye by voiding my warranty with a SC install would be stupid on my part. Not what I expected to deal with on a 7200 mile car, I've lost confidencein my car, but hey, **** happens right?
Thread Starter
Le Mans Master
Joined: Mar 2016
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From: 2019 CMG Z06
Update: parts finally trickled in last night so he started working on it. Called me this morning to tell me there’s some minor scoring on the cam. He ordered the cam this morning, but due to the strike, we have to wait and see. I told him he has my blessing to install a GM Performance cam if he can’t find the OEM one. 
Racer
Joined: Jul 2019
Posts: 441
Likes: 90
From: Truckee, CA
Assolutely! The RANGE AFM DISABLER electrically turns off the AFM switching gear. The AFM lifters never collapse, so AFM lifters never have the moving parts inside them moving, said moving which can accelerate failure.
But maybe you dislike the name RANGE. Do you like the name Lingenfelter Performance Engineering. when associated with corvettes? They can make AFM go away for you cheaper than RANGE, WITH some sweat equity on your part:
https://www.enginelabs.com/news/tech...delete-afmdod/
But the best way is to get those wonky AFM lifters out of your car, period:
https://help.summitracing.com/app/an...ment-%28afm%29
But maybe you dislike the name RANGE. Do you like the name Lingenfelter Performance Engineering. when associated with corvettes? They can make AFM go away for you cheaper than RANGE, WITH some sweat equity on your part:
https://www.enginelabs.com/news/tech...delete-afmdod/
But the best way is to get those wonky AFM lifters out of your car, period:
https://help.summitracing.com/app/an...ment-%28afm%29
The oil path plugging tool costs $95 and I think you have to take the heads off to get to the holes. That isn't much cheaper than getting Range.
I hope RitchieRichZ06 explains how the AFM can fail if the AFM is turned off.
Melting Slicks
Joined: Sep 2011
Posts: 3,009
Likes: 171
From: Vancouver Island
Good overview of the system and the typical cause of AFM failure here:
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
Thread Starter
Le Mans Master
Joined: Mar 2016
Posts: 9,123
Likes: 3,975
From: 2019 CMG Z06
Good overview of the system and the typical cause of AFM failure here:
https://m.youtube.com/watch?v=mkly7XmMsOs
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
https://m.youtube.com/watch?v=mkly7XmMsOs
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
Racer
Joined: Jul 2019
Posts: 441
Likes: 90
From: Truckee, CA
Good overview of the system and the typical cause of AFM failure here:
https://m.youtube.com/watch?v=mkly7XmMsOs
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
https://m.youtube.com/watch?v=mkly7XmMsOs
Even if you never properly engage AFM, the system itself could still malfunction. It’s not hard to imagine one of those “VLOM” solenoids going haywire and causing a mis-timed event. In the video, it’s SOP to replace the VLOM if an a-f-m lifter packs it in.
1. In normal 8 cyclinder operation, springs hold the solenoids shut. As long as they are shut, everything is relatively safe.
2. The system is most vulnerable when switching AFM on or off. Any mis-timing of a solenoid can cause a lot of damage.
3. Other things can cause mis-timing. For example, low oil pressure.
If you turn the AFM off via software like Range, you avoid mis-timing because the solenoids are always forced shut by the springs. The solenoids would never receive an electrical signal to open. Did I miss something?
Last edited by DugT; Oct 4, 2019 at 11:49 PM.
