Opinions on AFM and VVT

[TX2011SS]

Seeking opinions about an issue with my 2011 Camaro SS. I was doing some more research on the car and discovered something I did not know prior to buying it. The issue concerns the engine.

I thought the car had a 6.2 LS3. It actually has a 6.2 L99. Had I decoded the Vin number before purchasing the car I would have known that. Stupid mistake on my part but now I just have to decide if it is a big deal or not. The L99 is basically the same thing as an LS3 that has been slightly detuned with a couple additional features. First of all, the LS3 was only available in manual transmission Camaros that year. For the automatic like mine, the L99 was installed. The difference in horsepower is minimal. About 420 for the LS3 and 400 for the L99.

There are two features about the L99 that I do not like. They are AFM (Active Fuel Management) and VVT (Variable Valve Timing). With the first, AFM, the computer cuts off the fuel to four cylinders during light driving then cuts it back on during heavier acceleration. My problem with this is that if I wanted a four cylinder car, I would have bought a Kia. The engineers at GM probably created this feature to improve gas mileage for big engines. What a stupid feature in my opinion! I do not care about gas mileage with a car like this. I also discovered that this feature can be turned off by going into the computer. It can be totally disabled or turned off for the gears individually. For example, it can be turned off for all gears except for sixth if you want.

As for VVT, this is basically a feature that allows the computer to adjust the timing of the engine on the fly. There are a number of mechanical components that are integrated into the camshaft and valve system that interface with the computer then adjust the timing as needed while driving. Probably no big deal but I had a 2004 Chevrolet Trailblazer that used the same technology and it was constantly a problem. I think the components wear out fast and cause the engine to run poorly. Even dirty oil would cause the camshaft sensor to give faulty readings. My 2004 had over 100,000 miles so it may not be a big deal with the Camaro that only has 25,000 miles.

Am I concerned about nothing?

[Rock-It Man]

You can tune out the AFM if you want. The concern, apart from aesthetics, is that the AFM collapsing lifters had a tendency to bleed down after hours of down time, leading to a few seconds of clatter on start-up before they got pumped up again. This may or may not have caused abnormal wear, but it was embarrassing. The design was improved and there was a TSB for replacing the old ones. Tuning out the AFM function does nothing to address the weak lifters.

As for VVT, that is a feature of almost any modern engine you can think of. It can be used to tune the engine to provide a flatter torque curve, which is always a good thing. For example, while the LS3 has a higher peak HP, the L99 has a flatter torque curve and actually makes more HP in the commonly used range of 1500 to 3500 RPM. VVT is even more productive in engines with two cams per bank, as then the intake and exhaust valve profiles can be tuned independently for even better optimization.

Welcome to the 21st century.

[myold88]

OP: To answer your question, IMO yes. I've had my '10 SS L99 for almost 10 years.
Great engine that I've kept stock except for adding Solo axle back exhaust. Never a
sound from the engine. Still love this car after all this time. Drive and enjoy.

[qcman]

There's nothing wrong with the L99. Its a stout motor as far as I can tell. Mine is tuned so no more AFM & it shifts much firmer & faster. The L99 is probably the engine that wakes up the most from just a tune in the 5th Gen Camaro family. Tune it & enjoy!

[KJZ28]

I have a 2010 L99 with over 64,000 miles on it and no problems. As previously stated the VVT is good, AFM is a take it or leave it.

[TheFlyingBananaSS]

Get the afm tuned out.
Keep the vvt.
Put in 3.91 gears.
Hold on tight.

[pyroguy]

Welcome OP. Seeing you have few posts I assume you’re new to the group.

As for the L99 vs LS3 there’s plenty of debate over superiority between the two. 400 hp vs 426 hp stock isn’t much especially with gearing and modern transmissions.

AFM/DOD is one of the most disliked features of the automatic equipped cars. The lifters are a common enough failure point to be noted, but not enough to be recalled. That being said, a stock or even bolt on car that isn’t beat on too badly stands a very good chance of the lifters outlasting the car itself.

VVT is a hotly debated feature to keep or delete. If you’re not doing a cam to your car you’ll never have to really worry about whether to keep it or not. If you’re doing a cam swap there’s many people that will argue either way.

I just had a cam installed and multiple shops I talked to recommended deleting both AFM/DOD and VVT. The primary reason was less things to go wrong and the power increases are minimal down low and are less in the upper rpms where you would likely spend more of your time.

Don’t regret your purchase decision. It’s amazing how much a tune wakes up an automatic transmission in these cars! After I got my tune the car turned into a completely different animal!

[Aqua Blue RS/SS]

55000 no issues here.

[InFiD3ViL]

145,000 on my stock AFM lifters w/VVT, and not a single issue.

When I go with a cam on this stock bottom ended car that has driven more than halfway to the moon, I will keep the VVT.

[hrpiii]

I guess to answer your question.. Yes, you are worrying about nothing.


Now back to our L99 is faster than LS3!!

[Moto-Mojo]

Originally Posted by InFiD3ViL

145,000 on my stock AFM lifters w/VVT, and not a single issue.

This is encouraging! Viva la L99.

[myold88]

The only suggestion I have with the L99 is to keep the oil clean. In 10 years I've
completed 15 oil changes after 56,000 miles. Even after it's been parked for a few
weeks, I start it up and never a lifer noise.

[Moto-Mojo]

I’m probably on 7-8 oil changes with 11,500 miles. If I only took this good care of myself. : /

[pyroguy]

Originally Posted by hrpiii

Now back to our L99 is faster than LS3!!

What?! This can't be! Manual cars are ALWAYS faster than automatics! On an automatic power goes in and crushing disappointment comes out!