Cylinder Deactivation Issues?

KARNUT · July 25, 2017

It sounds ridiculous, but it is true. If you don't believe it, go to a place like Lima Peru, east of the Airport. They don't have modern emissions regs, or if they do, they don't enforce it. The crush of traffic and high emissions makes for a pretty nasty environment, especially in the hot sun. It's nauseating.

My early driving days (73)were in NJ-NY traffic. NJ had the strictest inspections I've dealt with. You could barely touch anything even then. Later 70s if you failed you could go to a service station and get reinspected and deals could be made. We use to change engines, exhaust etc to get inspected. We used to run quad exhaust with turn outs and caps. NJ would do spot road checks, get caught messing with emissions 10K fine.

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15 Z71 · July 25, 2017

I'm sure GM has spent millions of dollars testing these motors. And why would they keep making them if they have so many problems? I'm sure some have problems but most don't.

Nanotech Environmental · July 25, 2017

I'm sure GM has spent millions of dollars testing these motors. And why would they keep making them if they have so many problems? I'm sure some have problems but most don't.

Indeed they have.

The 5.3 in my 06 has been an absolutely amazing engine. Reliable as a rock. The only things I've done to it are a water pump (which turned out to be still fine, but was trying to solve an issue that turned out to be a rusted clamp at the rad), belts, plugs & wires. 200k miles on it and still runs fine & only uses a bit of oil in the winter.

Lots of people aren't having any issues with the new ones, so I'm sure that much of this is overblown.

Knightfall · July 25, 2017

It sounds ridiculous, but it is true. If you don't believe it, go to a place like Lima Peru, east of the Airport. They don't have modern emissions regs, or if they do, they don't enforce it. The crush of traffic and high emissions makes for a pretty nasty environment, especially in the hot sun. It's nauseating.

Richard Nixon founded the EPA after visiting China for the first time.

mookdoc6 · July 25, 2017

Richard Nixon founded the EPA after visiting China for the first time.

Tricky Dickey, Baby!

Thomcat · July 26, 2017

I used to be hell on wheels with a 4 speed. It was called flat shift or speed shift. 5 or 6 speed I was done. Kept missing 3rd.

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There's nothing like a 302 V8 hooked up to 4 spd short throw Hurst with a rod operated diaphragm clutch.

Edited July 26, 2017 by Thomcat

KARNUT · July 26, 2017

There's nothing like a 302 V8 hooked up to 4 spd short throw Hurst with a rod operated diaphragm clutch.

My last 4 speed was a 65 elcamino all original with one repaint. It had 327-250HP factory AC, close ratio and black paint. Put it on EBay just to see what it would bring, ending up selling. That was just 5 years ago.

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Grumpy Bear · July 26, 2017

The hp differential is insignificant for valid comparison......hp/weight ratio of the two are very close. Camaro is a heavier longitudinal RWD design, new '16 Malibu is lighter FWD with eggshell weight body......and a 6 spd manual in a Camaro might be more fun, but in a straight run cannot match the timing of the Camaro 6 spd automatic.

I was quoting for two Camaro's.

Thomcat · July 27, 2017

I was quoting for two Camaro's.

X2 Then, agreed. Actually I prefer the V6s in the Impala and Traverse for perceived wear and durability. Get feeling every time I punch that tiny 2.0T that something is getting ready to blow apart.....keep see visions of a hamster running in a wheel with DI crack being shoved up his nose.

MaverickZ71 · July 27, 2017

. . . . . Like I said, "Your next V8 will go all the way down to 2cyls" How's that making ya feel?

No, it sure as hell won't! I have been a life-long GM fan, but I will never own another vehicle with cylinder deactivation of any kind. I don't care if it's a V-12 or V-8 or inline-4. I'd rather ride a Harley or a bicycle or drive a 3-cylinder vehicle with 5 turbos hung on it!

A lot of you all must have either been blessed by the automotive gods, or maybe you don't change your own oil or check it often enough to know if you have an AFM problems. There is a reason GM mandated Dexos oil in 2010 and increased the oil capacity to 8 quarts in 2014. There are thousands of us for whom AFM has been a nightmare. Being forced to get on a first-name basis with your GM service manager (who says "all them AFMs do that sooner or later", and drives a Toyota, by the way) and service techs is not necessarily a good thing. My truck is a pretty good truck except for the problems caused by AFM. The General's AFM TSB "fixes" did little to help. I have to carry a case of oil wherever I drive, and check the oil at least once a week or after anything longer than a short trip. It idles and runs like crap because of the oil-fouled spark plugs. That's with running the best premium gas and Techron fuel system cleaner in it all the time, or it won't run at all. Now it sounds like one or more of the new lifters are going bad, after only 30K miles. 100K mile platinum or iridium plugs? Yeah, right. Only if your truck is one of the blessed perfect ones. I have to change these oil-fouled plugs more than I did back in the day when my Chevy had points in the ignition system. All of this mess for a supposed fuel mileage increase to help the environment. Mine actually increased 1-2 mpg when AFM was turned off first via a Range V8 module and later a Hypertech (stock except for turning off V4) tune! And all of the oil smoke out the tailpipe isn't helping the environment! Not all of us can afford to just upgrade to a new truck to dump an old problem one. Dumping a problem '96 Impala SS is how I got this Silverado in the first place. My dealer sales manager really really really tried to get me into a 2014 Sierra. Thank God that I didn't--everything that is right with my truck was wrong on those; recall after recall. The only 'Chevy shake' associated with my truck is the rough idle at stoplights.

PS A word of caution on fuel mileage--if you go by what the DIC says for your fuel mileage, it may very well be wrong. Mine consistently says 20-25% less fuel gallons used than what it actually uses. AFM or no, this thing only gets about 10mpg in town (hand-calculated) and 15-16 on the highway, and that's with the 6-speed. When I inquired about that years ago when the truck was new and still under warranty, the service writer smiled and said "yeah, most people never check that--they feel better about their vehicle when they think they're getting better gas mileage", and oh, by the way, there's no way to recalibrate it.

Edited July 27, 2017 by Maverick Z71

Grumpy Bear · July 27, 2017

A lot of you all must have either been blessed by the automotive gods, or maybe you don't change your own oil or check it often enough to know if you have an AFM problems.

Am I reading this right. Your commenting on new trucks but you own a 2009? Anyway, if your using that much oil AFM isn't your issue.

Nanotech Environmental · July 28, 2017

I have a theory that many of those who have oil consumption and oil fouling issues maybe went too easy on these during break-in. You have to get on it pretty good when new to properly seat all those rings & you only have a short window to do it. This is especially critical on an engine that has 4 of its cylinders shut down during operation & not have combustion pressure pushing out on those rings. If they're not seated, they will leak all the time; both blowby and oil, and even worse when they're in shut down mode. This would exasperate oil usage, as well as plug and intake valve fouling.

Grumpy Bear · July 28, 2017

BMEP, aka Brake Mean Effective Pressure. The effective mean pressure in the cylinder. The mean pressure is a guideline we use that can be calculated and measured but it is not the peak cylinder pressure.

A production engine with a compression ratio of 11:1 may have a peak cranking pressure of maybe 135 to 150 psig. That same pressure range could be obtained with a motor whose mechanical ratio was only 8.5:1. The difference is in the point ABDC the inlet valve closes and the butterfly is WOT.

In a running motor the peak pressure ranges 300 to 1000 psig. Race motors a bit higher. It takes a minimum of 90 psig to get the motor to start.

When a cylinder deactivates, AFM equipped motors, the valves close in order to trap a volume of air to be used as an air spring. As it is repeatedly cycled it heats up and the pressure comes near the low load operating pressure.

For this to work right the cylinder must be near zero percent leak down.

Today’s rings and cylinder wall compositions are very capable of creating this condition.

Food for thought:

Oil rings don’t ‘scrape off oil’ they are the mechanism that applies it at a controller rate from splash in the crankcase. The second ring is the scrapper.

Rings don’t ‘break in’, cylinder walls do. Rings are much harder than the walls they ride on.

The rings spring or preload pressure does not seal a cylinder. Gas pressure from above the ring migrates to the space behind the ring to force it against the cylinder wall. Spring tension just makes the introduction to get things started.

As physics would have it the higher the cylinder pressure the higher the ring sealing load meaning AFM deactivated cylinders get the same oil as the active cylinders in a cooler lower pressure environment that promotes LONGER ring life…not shorter.

The more lightly loaded the motor is, on average over time, the longer the motor lives. Com'on man, that’s just common sense.

Loaded cylinders are not under ‘more load’ or at least extreme loads that would wear them out. They operate in this V4 condition only when under low enough loads to permit safe engagement…unless someone is forcing them by a program to operate outside their designs. What is safe? No idea but I would have started testing at 500 psig.

If you want your AFM on more you need to find ways to lower the motors load enough to keep it in the ‘safe zone’ GM designed it to operate in. This is its own topic and the subject of my person truck build thread.

Finally, rings don’t ‘plug’ due to high oil volumes. But they can be flooded to the point that the scrapper ring is unable to remove it effectively. Think of it as hydroplaning. They can gum due to abnormally high temperatures that promote varnishing and gumming. Also from contamination. But not from flooding or AFM operation where flooding is well controlled. Something GM has addresses successfully.

Edited July 28, 2017 by Grumpy Bear

Thomcat · July 28, 2017

No, it sure as hell won't! I have been a life-long GM fan, but I will never own another vehicle with cylinder deactivation of any kind. I don't care if it's a V-12 or V-8 or inline-4. I'd rather ride a Harley or a bicycle or drive a 3-cylinder vehicle with 5 turbos hung on it!

A lot of you all must have either been blessed by the automotive gods, or maybe you don't change your own oil or check it often enough to know if you have an AFM problems. There is a reason GM mandated Dexos oil in 2010 and increased the oil capacity to 8 quarts in 2014. There are thousands of us for whom AFM has been a nightmare. Being forced to get on a first-name basis with your GM service manager (who says "all them AFMs do that sooner or later", and drives a Toyota, by the way) and service techs is not necessarily a good thing. My truck is a pretty good truck except for the problems caused by AFM. The General's AFM TSB "fixes" did little to help. I have to carry a case of oil wherever I drive, and check the oil at least once a week or after anything longer than a short trip. It idles and runs like crap because of the oil-fouled spark plugs. That's with running the best premium gas and Techron fuel system cleaner in it all the time, or it won't run at all. Now it sounds like one or more of the new lifters are going bad, after only 30K miles. 100K mile platinum or iridium plugs? Yeah, right. Only if your truck is one of the blessed perfect ones. I have to change these oil-fouled plugs more than I did back in the day when my Chevy had points in the ignition system. All of this mess for a supposed fuel mileage increase to help the environment. Mine actually increased 1-2 mpg when AFM was turned off first via a Range V8 module and later a Hypertech (stock except for turning off V4) tune! And all of the oil smoke out the tailpipe isn't helping the environment! Not all of us can afford to just upgrade to a new truck to dump an old problem one. Dumping a problem '96 Impala SS is how I got this Silverado in the first place. My dealer sales manager really really really tried to get me into a 2014 Sierra. Thank God that I didn't--everything that is right with my truck was wrong on those; recall after recall. The only 'Chevy shake' associated with my truck is the rough idle at stoplights.

PS A word of caution on fuel mileage--if you go by what the DIC says for your fuel mileage, it may very well be wrong. Mine consistently says 20-25% less fuel gallons used than what it actually uses. AFM or no, this thing only gets about 10mpg in town (hand-calculated) and 15-16 on the highway, and that's with the 6-speed. When I inquired about that years ago when the truck was new and still under warranty, the service writer smiled and said "yeah, most people never check that--they feel better about their vehicle when they think they're getting better gas mileage", and oh, by the way, there's no way to recalibrate it.

If you own an '09 aluminum AFM then you definitely have one of the "bum" engine designs. The updated valve covers with relocated PCV valve baffle/takeoff location began mid '09........if you have an early '08 build you've got the bad cover also. The most important mod was the AFM discharge baffle in the sump which didn't hit production until post 1/2011 which was about the time they also began to install upgraded AFM lifters. So if your engine lacks these mods and you didn't go crazy with frequent oil changes well in excess of advice of the "engine killer" DIC.....you're correct.....your engine is doomed to be a burner once the oil control ring sets clog up and freeze. That's why I dumped a perfectly good '07 Avalanche... the dealer said they wouldn't do the mods prophylactically before it became an oil burner and that's why I traded for a '12.

Seems my '12, '13 and '16 are all blessed, having all been anointed with GM's updated valve cover, PCV takeoff, AFM valve shield and redesigned updated valve lifters. The '07 to 1/2011 aluminum AFM engines that have not had mods done before their oil ring sets clogged and absent frequent oil changes well in excess of the DIC before they become an oil burner to delay this clogging are irretrievably "cursed". Even a GM exorcism with upper end solvent to free up the frozen ring sets and AFM baffle will not drive out the damage done by the evil AFM demon.....if it is already burning oil the only salvation is a complete piston replacement accompanied by all the other '07 - '11 mods.

And I'm no fan of AFM but if it doesn't annoy me I don't annoy it by updating and plugging in my Range pulled from the '07. And the mileage gains I received attributable to AFM on the older 5.3's and the new DI 5.3 are accurate because I would never rely on that engine killing DIC to provide any accurate data on anything other that drive wheel engagement or vehicle angle. Honest 17-20 mpg mixed small town/mountain driving and can beat 20 mpg constant speed non stop IS driving.!

Thomcat · July 30, 2017

Indeed they have.

The 5.3 in my 06 has been an absolutely amazing engine. Reliable as a rock. The only things I've done to it are a water pump (which turned out to be still fine, but was trying to solve an issue that turned out to be a rusted clamp at the rad), belts, plugs & wires. 200k miles on it and still runs fine & only uses a bit of oil in the winter.

Lots of people aren't having any issues with the new ones, so I'm sure that much of this is overblown.

Shouldn't be any problems with an '06 or the new ones. AFM wasn't introduced to the 5.3 until '07 production and the engines' faulty design with potential for oil burning wasn't corrected until post 1/2011 when engines were modified with new valve covers/PCV takeoff, AFM discharge valve shield and redesigned AFM lifters.

Of course if you don't treat any engine properly during the early ring seating phase you can turn any engine into a latent oil burner.