L99 engine - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Captainjapan · 12-06-2011, 08:27 AM

I read somewhere that the L99 engine turns off 4 cylinders off when traveling on the highway. Is this true and how does this work? At what speed does this happen?

Dukes117 · 12-06-2011, 08:34 AM

It happens all the time, when in park, neutral, reverse, and even sometimes when you're drag racing. The ONLY way to disable this system is to get twin turbo's. That's the ONLY way. Don't you hear the fart can noise when you're in park? That because you're only running 2 cylinders in that situation. Believe it or not, in 6th gear the car will actually run on 1 cylinder. Crazy huh.

first one · 12-06-2011, 08:44 AM

Quote:

Originally Posted by Dukes117

It happens all the time, when in park, neutral, reverse, and even sometimes when you're drag racing. The ONLY way to disable this system is to get twin turbo's. That's the ONLY way. Don't you hear the fart can noise when you're in park? That because you're only running 2 cylinders in that situation. Believe it or not, in 6th gear the car will actually run on 1 cylinder. Crazy huh.

Not so!

HDDAN · 12-06-2011, 08:47 AM

Quote:

Originally Posted by Dukes117

It happens all the time, when in park, neutral, reverse, and even sometimes when you're drag racing. The ONLY way to disable this system is to get twin turbo's. That's the ONLY way. Don't you hear the fart can noise when you're in park? That because you're only running 2 cylinders in that situation. Believe it or not, in 6th gear the car will actually run on 1 cylinder. Crazy huh.

Are you really sure about that? My L99 uses engine braking to turn the engine backwards when braking to reclaim lost gasoline. There are giant kinnifling pins in the rear axles. Mine will run on LESS than one cylinder. You must have a lemon. Mine also reclaims gasoline when it is in reverse.

Dukes117 · 12-06-2011, 08:49 AM

Ah, yes ^. My mistake.

axis · 12-06-2011, 08:49 AM

Quote:

Originally Posted by first one

Not so!

I'm sure he was just kidding.

OP:
Do a search for AFM on here and i'm sure you'll find out all you want to know about it. Basically, under a certain set of circimstances, the car will deactivate 4 cylinders in order to conserve fuel. They reactivate as soon as you put X amount of load on the engine. AFM is active in pretty much all gears so you can go into AFM cruising around the neighborhood.

v6sonoma · 12-06-2011, 09:30 AM

Quote:

Originally Posted by Captainjapan

I read somewhere that the L99 engine turns off 4 cylinders off when traveling on the highway. Is this true and how does this work? At what speed does this happen?

Now that they are done having fun the real answer is yes it does. It runs in "4cyl" mode in certain situations to help save fuel. The L99 also has variable valve timing as well. The addition of these two items are also the reason why it's output is slightly less then the manuals LS3 and why when you want to get large amounts of power it costs more. (since those items need to be replaced with LS3 gear) Hope that helps.

Russell James · 12-06-2011, 09:52 AM

The AFM and variable valve timing isn't really what loses the hp. The LS3 has higher compression, and different cam lift/timing. If the compression and cam specs were the same, theoretically the peak hp would be the same. Problem being though is the L99 must use a cam that is friendly with the AFM lifters (low lift), and piston clearance to allow for the variable valve timing.

mpyle007 · 12-06-2011, 09:54 AM

The AFM absolutely drives me nuts! But this is just me. Some people dont find a problem with it. I can feel it kick in and it creates an exhaust note that sounds terrible. I guess you have to understand what you are hearing. I am adding multiple bolt ons around my time off in the holiday and getting a Tune. I cant wait for the AFm to be turned off! They say once the car is tuned the L99 is a different beast.

Any questions you have feel free to roam this forum and search for topics. You will learn a lot. Great people on here and lots of experience with these cars.

JDP Tech · 12-06-2011, 10:18 AM

When I had AFM (Active Fuel Management) and VVT (Variable Valve Timing) I actually didn't hate it too much. I loved the up to 33 mpg (on several occasions) I got from it. It does get annoying at times, most so when you have an aftermarket exhaust system, it really amplifies the change in noise.

Unfortunately (or fortunately, depending on how you look at it), it can be active in all gears and forward moving shifter positions, all speeds, and most RPMs. Some have claimed you can temporarily deactivate it if you go into manual mode, shift up down then up again, it should stay off until you take it out of manual mode.

The only way to permanently turn it off is if you get the computer tuned to turn it off. But some problems still exist with it; the lifters it uses to deactivate cylinders are somewhat prone to failure when larger stresses are placed on the engine, and sometimes even in stock form. It's not too common, but it has happened a lot. When a lifter fails, the engine is for the most part dead in the water until it is repaired. It will usually still run, but its not a good idea to do so.

The only true way to get rid of AFM, and also get rid of the sketchy lifters, is to replace the lifters and engine valley cover, and while you're in there, might as well replace the cam too, and have an awesome sounding, performing, and feeling car!

- Jeremy

Ricky11SS · 12-06-2011, 10:26 AM

Fact: Use the tap shifts and just press the downshift while running like at 30 mph and it will deactivate. 100% sure

JDP Tech · 12-06-2011, 10:52 AM

There is a lot of mis-information and opinions out there about using tap shift and AFM.
The above method, or any other method for that matter never worked for me. It was always active (when conditions were met), no matter what I did with the gear shifter or tap buttons. It may vary from car to car, who knows.

Cpanthers85 · 12-06-2011, 11:14 AM

JDP- I am having the AFM turned off via tune, but I have no intentions of doing a LS3 conversion, any time soon, at least... Should I still replace the the 4 lifters?

Ricky11SS · 12-06-2011, 11:15 AM

Quote:

Originally Posted by Tech@JDP

There is a lot of mis-information and opinions out there about using tap shift and AFM.
The above method, or any other method for that matter never worked for me. It was always active (when conditions were met), no matter what I did with the gear shifter or tap buttons. It may vary from car to car, who knows.

may ur right
but it worked for me

12-06-2011, 08:27 AM	#1
Captainjapan Captain SS / 2 Drives: 2010 Camaro SS2/RS Join Date: Sep 2011 Location: Niagara Falls, Canada Posts: 62	L99 engine I read somewhere that the L99 engine turns off 4 cylinders off when traveling on the highway. Is this true and how does this work? At what speed does this happen?

12-06-2011, 09:54 AM	#9
mpyle007 Drives: 2011 Camaro 2SS L99 Join Date: Jun 2011 Location: Texas Posts: 301	The AFM absolutely drives me nuts! But this is just me. Some people dont find a problem with it. I can feel it kick in and it creates an exhaust note that sounds terrible. I guess you have to understand what you are hearing. I am adding multiple bolt ons around my time off in the holiday and getting a Tune. I cant wait for the AFm to be turned off! They say once the car is tuned the L99 is a different beast. Any questions you have feel free to roam this forum and search for topics. You will learn a lot. Great people on here and lots of experience with these cars. __________________ *2011 Camaro 2SS L99 A6* Rotofab CAI w/ race scoop TSP Long tube headers w/ high flow cats and full x-pipe GMPP axle back exhaust system Custom Dyno tune by ARD (Advanced Racing Dynamics) BMR 1.4" Springs all four corners "There is no replacement for displacement"

12-06-2011, 11:14 AM	#13
Cpanthers85 Drives: 2011 Camaro 2SS RS Join Date: Jul 2011 Location: Pittsburgh, PA Posts: 470 View My Garage	JDP- I am having the AFM turned off via tune, but I have no intentions of doing a LS3 conversion, any time soon, at least... Should I still replace the the 4 lifters? __________________ 2011 2SS/RS L99 2017 Chevy SS 1979 Z28 Mods: Kooks Long Tube Headers, RotoFaB EForce CAI, American Thunder Catback Exhaust, PFADT Stage 1 Drag Kit + Front Sway Bar, GM Strut Tower Bar. ZL1 Fuel Pump. Nitto NT05R. RX Catch Can.LS9 Cam and Springs.LS3 Conversion.JRE Fuel Rail Upgrade.Edelbrock Eforce.60# Eforce Injectors.Extreme Racing Tune. 523/495 MY BUILD THREAD

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12-06-2011, 08:34 AM	#2
Dukes117 H0TWH331S Drives: '11 SW SS(SOLD) '12 IOM SS (order) Join Date: Nov 2011 Location: Astoria, NY Posts: 225	It happens all the time, when in park, neutral, reverse, and even sometimes when you're drag racing. The ONLY way to disable this system is to get twin turbo's. That's the ONLY way. Don't you hear the fart can noise when you're in park? That because you're only running 2 cylinders in that situation. Believe it or not, in 6th gear the car will actually run on 1 cylinder. Crazy huh.

12-06-2011, 08:49 AM	#5
Dukes117 H0TWH331S Drives: '11 SW SS(SOLD) '12 IOM SS (order) Join Date: Nov 2011 Location: Astoria, NY Posts: 225	Ah, yes ^. My mistake.

12-06-2011, 09:52 AM	#8
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	The AFM and variable valve timing isn't really what loses the hp. The LS3 has higher compression, and different cam lift/timing. If the compression and cam specs were the same, theoretically the peak hp would be the same. Problem being though is the L99 must use a cam that is friendly with the AFM lifters (low lift), and piston clearance to allow for the variable valve timing.

12-06-2011, 10:18 AM	#10
JDP Tech Drives: 2010 CGM Camaro 2SS/RS 429 LSX/F1X Join Date: Aug 2011 Location: Sandy, UT Posts: 429	When I had AFM (Active Fuel Management) and VVT (Variable Valve Timing) I actually didn't hate it too much. I loved the up to 33 mpg (on several occasions) I got from it. It does get annoying at times, most so when you have an aftermarket exhaust system, it really amplifies the change in noise. Unfortunately (or fortunately, depending on how you look at it), it can be active in all gears and forward moving shifter positions, all speeds, and most RPMs. Some have claimed you can temporarily deactivate it if you go into manual mode, shift up down then up again, it should stay off until you take it out of manual mode. The only way to permanently turn it off is if you get the computer tuned to turn it off. But some problems still exist with it; the lifters it uses to deactivate cylinders are somewhat prone to failure when larger stresses are placed on the engine, and sometimes even in stock form. It's not too common, but it has happened a lot. When a lifter fails, the engine is for the most part dead in the water until it is repaired. It will usually still run, but its not a good idea to do so. The only true way to get rid of AFM, and also get rid of the sketchy lifters, is to replace the lifters and engine valley cover, and while you're in there, might as well replace the cam too, and have an awesome sounding, performing, and feeling car! - Jeremy

12-06-2011, 10:26 AM	#11
Ricky11SS Drives: 2011 Camaro SS L99 Join Date: Dec 2011 Location: Hidalgo Tx Posts: 249	Fact: Use the tap shifts and just press the downshift while running like at 30 mph and it will deactivate. 100% sure

12-06-2011, 10:52 AM	#12
JDP Tech Drives: 2010 CGM Camaro 2SS/RS 429 LSX/F1X Join Date: Aug 2011 Location: Sandy, UT Posts: 429	There is a lot of mis-information and opinions out there about using tap shift and AFM. The above method, or any other method for that matter never worked for me. It was always active (when conditions were met), no matter what I did with the gear shifter or tap buttons. It may vary from car to car, who knows.