AFM actuators have failed again on track for my Z51
09-28-2015, 07:26 PM
#61
Instructor
I hate to hear of folks having this issue at all levels of drivers from beginner to advanced. I'm thinking it is only a matter of time before I see it. However, it is strange that after 12 track days, this hasn't happened. I never use the 4 cylinder mode, could this have something to do with it? Or just plain luck? I'm an intermediate driver at best.
I probably have jinxed it now!
I probably have jinxed it now!
09-28-2015, 07:33 PM
#62
I hate to hear of folks having this issue at all levels of drivers from beginner to advanced. I'm thinking it is only a matter of time before I see it. However, it is strange that after 12 track days, this hasn't happened. I never use the 4 cylinder mode, could this have something to do with it? Or just plain luck? I'm an intermediate driver at best.
I probably have jinxed it now!
I probably have jinxed it now!
It's automatic but since I'm using paddle shift on track, v4 should not engage anytime on track, it's just too much heat i guess.
10-03-2015, 04:36 PM
#63
I got a CEL, and metal clanking noise from rear end, especially when switching to v4 mode, I assume it's the AFM failure you guys talked about. I also heard a different rattling noise from rear end, when accelerating with 50% gas pedal on street.
To be honest, this is really disappointing, considering that might also happen for my future track events.
To be honest, this is really disappointing, considering that might also happen for my future track events.
I walked into the dealer and gave them the codes on a printout, and pretty much told them what it was. They spend a 2 days on it, to finally agree with me - have to order new AFM actuators. Returned the car. After a week, actuators were in. I bring the car back. They re-open it all up (rear has to come out). Then they find that not only were the actuators toasted, but the valves themselves were broken inside.
To their credit, they located an actuator on a dealer in another state and had a technician drive over to pick it up. (I had to leave for a track day, that day). They put it in, but couldn't clear the CEL. Claimed that the car need to be put into re-learn mode and wouldn't relearn. They spent more hours with GM techs, and concluded that the muffler was also toast, and needed to be replaced. It would take 4-5 days to get one. They put the car back together. Said car was OK to drive according to GM, even though the CEL was on.
The clanking noise was gone, but the metallic noise at 30-40% acceleration was there, and the car sounded horrible even at idle - metallic vibration and such.
Anyway, I instructed for two days on it. Mostly I was giving other instructors and students rides (it was a brand new track, and most had never been on it), so wan't really pushing it. I used my typical routine, upshift before 5,000 RPM, minimize shifting and high RPM to prevent transmission overheating. Was able to complete 16-20 min on track without overheating, which was very good for my car. Temps were 45-65F.
Car ran fine otherwise.
Finally this past week muffler came in. Took two days to put it in an reprogram. Car now runs totally fine and sounds again like a Corvette.
I will likely only run one more track day this year on it - a track with 4 or so WOT segments. So, lets see if it holds up.
I still love the car's handling, and the engine is great - just the right amount of power (enough to make you work on it for putting the power down, but not overwhelming the chassis).
But it is a shame that everything in the rear of the car seems to overheat and fail on track.
11-10-2015, 07:23 PM
#65
Instructor
Member Since: Jan 2008
Location: Fort Walton beach Florida
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Cars back at the dealer getting another set of actuators after one day at AMP. Air temp. never went above 65 that day. Oil temps seem to get higher than any of my other track days. Also having problems with stock front tires losing chunks of rubber in the centers running factory alignment.
11-11-2015, 05:53 PM
#66
Burning Brakes
Thread Starter
Cars back at the dealer getting another set of actuators after one day at AMP. Air temp. never went above 65 that day. Oil temps seem to get higher than any of my other track days. Also having problems with stock front tires losing chunks of rubber in the centers running factory alignment.
I also had my OEM MPSS tires losing chunks in the center, like the tire was melting from the heat. I decided to only run R compounds after that and leave the Super Sports for the street. Since my AFM actuators have failed every single day I have taken it to the track 5 times now, GM just can't offer a solution except to keep replacing the actuators. Heat wrap on the exhaust pipes did nothing to solve the issue. When I was at the SEMA show last week, GM had solutions for transmission and engine coolant overheating on the Z51 manual as part of their SCCA T1 class track package, but nothing for the AFM actuators. I spoke to an engineer there and he said he would inquire about a solution for the AFM problems, as he didn't seem to have heard about it. I am waiting for his answer.
AFM actuator failure has nothing at all to do with V4 mode actuation. It is just that the heat from the exhaust pipe after running the car hard on track for 30 minutes straight melts the actuators as shown by the tell-tale semi-circle of molten plastic when they get un-bolted from the exhaust pipe. The actuators are not being used when they fail. On every single engine startup, the chassis control module checks their operation, and if defective, turns on the CEL. You have to turn the engine on and off to get the CEL as it won't come on at the moment of failure, just at startup.
If the car is driven at the beginner or intermediate level on track, then one is much less likely to get an AFM actuator failure as the exhaust will just not be getting hot enough.
GM Corvette and Camaro Brand Quality Manager looking after my case has provided nothing in terms of a solution. Anyone having this issue should get a case number from GM Customer Care and have their dealer check with their own GM Brand Quality Manager. There has to be a fix. Report back here if you find anything out.
11-11-2015, 10:13 PM
#68
Instructor
Member Since: Jan 2008
Location: Fort Walton beach Florida
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I have run the remaining runs for the day both times they have failed with no other issues. I also have a case number with GM Customer Care. Hoping to get the car back from the dealership tomorrow.
11-12-2015, 08:14 AM
#69
I also had my OEM MPSS tires losing chunks in the center, like the tire was melting from the heat. I decided to only run R compounds after that and leave the Super Sports for the street. Since my AFM actuators have failed every single day I have taken it to the track 5 times now, GM just can't offer a solution except to keep replacing the actuators. Heat wrap on the exhaust pipes did nothing to solve the issue. When I was at the SEMA show last week, GM had solutions for transmission and engine coolant overheating on the Z51 manual as part of their SCCA T1 class track package, but nothing for the AFM actuators. I spoke to an engineer there and he said he would inquire about a solution for the AFM problems, as he didn't seem to have heard about it. I am waiting for his answer.
AFM actuator failure has nothing at all to do with V4 mode actuation. It is just that the heat from the exhaust pipe after running the car hard on track for 30 minutes straight melts the actuators as shown by the tell-tale semi-circle of molten plastic when they get un-bolted from the exhaust pipe. The actuators are not being used when they fail. On every single engine startup, the chassis control module checks their operation, and if defective, turns on the CEL. You have to turn the engine on and off to get the CEL as it won't come on at the moment of failure, just at startup.
If the car is driven at the beginner or intermediate level on track, then one is much less likely to get an AFM actuator failure as the exhaust will just not be getting hot enough.
GM Corvette and Camaro Brand Quality Manager looking after my case has provided nothing in terms of a solution. Anyone having this issue should get a case number from GM Customer Care and have their dealer check with their own GM Brand Quality Manager. There has to be a fix. Report back here if you find anything out.
AFM actuator failure has nothing at all to do with V4 mode actuation. It is just that the heat from the exhaust pipe after running the car hard on track for 30 minutes straight melts the actuators as shown by the tell-tale semi-circle of molten plastic when they get un-bolted from the exhaust pipe. The actuators are not being used when they fail. On every single engine startup, the chassis control module checks their operation, and if defective, turns on the CEL. You have to turn the engine on and off to get the CEL as it won't come on at the moment of failure, just at startup.
If the car is driven at the beginner or intermediate level on track, then one is much less likely to get an AFM actuator failure as the exhaust will just not be getting hot enough.
GM Corvette and Camaro Brand Quality Manager looking after my case has provided nothing in terms of a solution. Anyone having this issue should get a case number from GM Customer Care and have their dealer check with their own GM Brand Quality Manager. There has to be a fix. Report back here if you find anything out.
Two other things I have done, my pipes are all ceramic coated back to the X Pipe and thermally coated inside and out. Not sure if that is a difference maker but as stated if somebody was going to have a failure it should have been me.
11-12-2015, 08:21 PM
#70
Burning Brakes
Thread Starter
I am an instructor and run Road America, I have done probably close to 4,000 track miles on my Z51 and have had no failures, but I did wrap my exhaust before I ever went to the track. I am running 2:32 at Road America so I am definitely not taking it easy. Not sure why I haven't had any failures but the car runs great for me.
Two other things I have done, my pipes are all ceramic coated back to the X Pipe and thermally coated inside and out. Not sure if that is a difference maker but as stated if somebody was going to have a failure it should have been me.
Two other things I have done, my pipes are all ceramic coated back to the X Pipe and thermally coated inside and out. Not sure if that is a difference maker but as stated if somebody was going to have a failure it should have been me.
I wrapped my exhaust pipes as shown in the pictures I posted as well and it made no difference as the AFM actuators failed regardless. The operations manger at Spring Mountain told me that they have had many failures of the AFM actuators on their Z51's with instructors driving the cars fast and that GM knew about it, but that failures were less frequent when they changed their 2014's for 2015's. Of course their school runs cars only for a few laps at a time and then they rotate the car order and that cools the cars, which is shown in the videos from Spring Mountain. My contacts with GM via my dealer SA confirms that they know about the failures but can offer no solution at this time. As others in this thread have shown, they are having failures as well. Perhaps the combination of the long straights at Road America provide more cooling airflow along with the ceramic coating you mention, but that is for sure not OEM. My car is all OEM and GM Brand Quality manager looking after my case made the dealer remove the heat wrap, which they gave it back to me. So I am at a loss as to what to do.
11-13-2015, 07:07 AM
#73
Burning Brakes
Thread Starter
If it was only as easy as taking the AFM actuators off the car. Every time a non Z-06 car powers up the Chassis Control Module (CCM) tests their operation by sending a signal to operate them and looks for a signal back that confirms they have moved to the active (closed) position, and then de-activates them. If it does not get that signal back it sets a code and turns on the CEL (MIL)
Option 1 - Leave them on but remove plug: they will melt anyway from the heat, and once that happens, you have a permanent CEL
Option 2 - Un-mount them and leave them plugged-in. Without the return spring on the exhaust pipe AFM valve and the mechanical stop provided by the valve, the actuator won't give the proper signal back to the CCM and you get a full-time CEL but your actuators do not fail
Option 3 - convert to Z06 axle back which does not have the valves. Same effect as option 1 or 2 since the CCM module will not get its feedback signal when sending an activate AFM valve command sequence.
I know a tune with a Diablo or similar, potentially warranty voiding, can tune out the operation of the AFM actuator while driving, but I have not heard that anyone can stop the AFM test by the CCM module on start-up. If that is possible, then one might be able to just un-mount them and disconnect them, so no failure and no CEL. But I have never heard of anyone doing that.
One could always just drive the car with the CEL on permanently, but then you would never know if your car had thrown a second code. Plus it drives me nuts to drive with a CEL on. If anyone has found a solution that works, chime in.
Option 1 - Leave them on but remove plug: they will melt anyway from the heat, and once that happens, you have a permanent CEL
Option 2 - Un-mount them and leave them plugged-in. Without the return spring on the exhaust pipe AFM valve and the mechanical stop provided by the valve, the actuator won't give the proper signal back to the CCM and you get a full-time CEL but your actuators do not fail
Option 3 - convert to Z06 axle back which does not have the valves. Same effect as option 1 or 2 since the CCM module will not get its feedback signal when sending an activate AFM valve command sequence.
I know a tune with a Diablo or similar, potentially warranty voiding, can tune out the operation of the AFM actuator while driving, but I have not heard that anyone can stop the AFM test by the CCM module on start-up. If that is possible, then one might be able to just un-mount them and disconnect them, so no failure and no CEL. But I have never heard of anyone doing that.
One could always just drive the car with the CEL on permanently, but then you would never know if your car had thrown a second code. Plus it drives me nuts to drive with a CEL on. If anyone has found a solution that works, chime in.
01-28-2016, 09:48 AM
#74
Instructor
Just experienced first AFM failure, on my wife's Z51.....dont get me wrong she likes a bit of spirited driving ON THE STREET!!!! LOL only 4700 miles and our first failure. Actually occurred after installation of the Magnaflow system and they diagnosed the failure. They actually took care of the actuator cost (good guys) but I am going to take the failed actuator and attempt to get a reimbursement for Magnaflow and or at least get a case number. Just wondering if there was any update/fix to this
Ryan
Ryan
01-29-2016, 01:55 PM
#75
Burning Brakes
Thread Starter
Just experienced first AFM failure, on my wife's Z51.....dont get me wrong she likes a bit of spirited driving ON THE STREET!!!! LOL only 4700 miles and our first failure. Actually occurred after installation of the Magnaflow system and they diagnosed the failure. They actually took care of the actuator cost (good guys) but I am going to take the failed actuator and attempt to get a reimbursement for Magnaflow and or at least get a case number. Just wondering if there was any update/fix to this
Ryan
Ryan
01-30-2016, 02:54 AM
#77
Instructor
Well for me and I think some one else mentioned this happened to them as well...........As luck would have it I just installed the Magnaflow system on my wifes Z51....drove it a few days then while she was on the way home a loud "clacking" sound started. When I looked underneath the car at home when she started it the actuator was constantly opening and closing and the check engine light came on. I thought it was something wrong with the Magnaflow axle over pipe which has their valve on it. I took the car to Magnaflow and they diagnosed the problem as the actuator. They actually replaced the actuator for me!!!!!!!!!!! Outstanding customer service!!!! They actually wanted the failed actuator to dissect it and see if they could determine the cause of failure
I do not have NPP so the actuator on the valve before the muffler failed...only the drivers side for now...car only has 5300 miles on it,,,,
Ryan
I do not have NPP so the actuator on the valve before the muffler failed...only the drivers side for now...car only has 5300 miles on it,,,,
Ryan
01-30-2016, 02:53 PM
#78
I have been following this thread as I suspect I have a problem with my AFM actuators(2015 ,C7 coupe, A8 NPP)
I don't track the car but I have what seems to be very noisy actuators. My understanding is that any time the engine switches from V8 to V4 the AFM actuators close the valves. I watch the switch from V8 to V4 on the instrument icon and every time the engine switches to V4 mode I hear what sounds like a grinding noise.
From following this thread would I be correct in assuming that if it is the AFM actuators making the noise ,can they be replaced WITHOUT dropping the exhaust ?
In advance ,thanks for you help. Doug.
I don't track the car but I have what seems to be very noisy actuators. My understanding is that any time the engine switches from V8 to V4 the AFM actuators close the valves. I watch the switch from V8 to V4 on the instrument icon and every time the engine switches to V4 mode I hear what sounds like a grinding noise.
From following this thread would I be correct in assuming that if it is the AFM actuators making the noise ,can they be replaced WITHOUT dropping the exhaust ?
In advance ,thanks for you help. Doug.
01-30-2016, 02:58 PM
#79
Just to better explain the above the Grinding noise I hear during the switch from V8 to V4 is just momentary at switch over, the length of time that it would take for the Valve to move.......not a continuous grinding sound....
02-02-2016, 07:33 PM
#80
Instructor
BS
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