Chevrolet's New Cylinder Deactivation System Is a Game-Changer

2019 Chevrolet Silverado 1500 Exterior

By Chad Kirchner

During the reveal of the 2019 Chevrolet Silverado 1500 at the 2018 North American International Auto Show in Detroit, Chevy said the new truck would have six engine options. Those are the 6.2-liter V-8, the 4.3-liter V-6, the new 2.7-liter turbocharged four-cylinder, the 3.0-liter turbo-diesel and two versions of the 5.3-liter V-8.

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The two 5.3-liter options depend on which technology is used for engine management and cylinder deactivation. Chevrolet broke down the differences for auto journalists at a technical briefing Thursday in Milford, Mich., then allowed us to drive a 2019 Chevrolet Silverado 1500 equipped with the reengineered 5.3-liter V-8.

New Cylinder Deactivation System

The base 5.3-liter V-8 uses an active fuel management system that deactivates cylinders to conserve fuel. It's similar to the setup in the 2018 Silverado and can either run the truck on four or eight cylinders. The new setup, also on the 6.2-liter V-8, uses what Chevy is calling Dynamic Fuel Management. This technology can run on all eight cylinders or as few as one. But it's way more advanced than that. The oil control valves on the new DFM setup are located in the engine block and there is one for each cylinder. There are also two switching lifters for each cylinder, totaling 16. Building the oil control valves into the block shortens the distance required for the oil to travel and speeds up response time.

The firing pattern for the new engine remains the same: 1-8-7-2-6-5-4-3. What is different is that the system can control which cylinder fires in the rotation. Chevrolet uses fractions to describe which mode the engine is in. For a basic example, 1/2 mode fires cylinders 8, 2, 5 and 3 during each cycle. That's the same as V-4 mode in the older active fuel management setup. It gets more complicated when fewer cylinders are required. In a 1/3-firing fraction, the engine has to cycle three complete times for each cylinder to fire once. On the first cycle, 7 and 5 fire. On the second cycle, it's 1, 2 and 4. On the third cycle, it's 8, 6 and 3. Eventually every cylinder fires, but the system can control individually which cylinders fire on which rotation.

System Benefits

The benefits to the driver are multifold. Under the standard EPA test cycle with the old engine, the engine operated in four-cylinder mode 52 percent of the time. The other 48 percent of the time it was running as a full V-8.

Using the same test cycle, the upgraded engine operated in V-8 mode only 39 percent of the time. It then operated between four- and eight-cylinder modes 45 percent of the time. Finally, 16 percent of the time the engine operated on less than four cylinders. Using this new setup, the 5.3-liter Chevy can use up to 29 different cylinder firing patterns. In the production version of the Silverado, it uses only 17.

2019 Chevrolet Silverado 1500 5.3-Liter V-8 Engine

So why did some get cut? If you've driven the 2018 Silverado 1500 with cylinder deactivation, you can probably tell when it's running on four cylinders. It's a bit harsher and there's an audible difference in how the engine sounds. Of the 29 different firing patterns, 12 resulted in similar effects. Engineers had a primary goal of making this all imperceptible to the driver.

To assist with smoothing out the roughness, Chevy is also uses a centrifugal pendulum absorber in the torque converter like it uses in the new 2.7-liter four-cylinder and the Chevrolet Colorado diesel.

Aside from reducing unpleasantness in the cabin, why else did Chevrolet switch to this system? Improving overall performance in all driving situations. By controlling cylinders individually, the engine can improve response and efficiency more often. In fact, the system makes changes every 12.5 milliseconds. That's 80 decisions a second.

Jordan Lee, Chevrolet chief engineer of small-block engines, noted that there are nearly 66,000 lines of computer code devoted specifically to the new cylinder-deactivation function in the new engine control unit. The system takes into account more than 29,000 different variables to know which profile to run and when to run it.

Inside the truck, the V-4 and V-8 indicators are gone. Because the system is changing firing profiles on demand, there isn't a display to replace it. If you want to really geek out over this technology when you drive the truck, you'll be a bit disappointed.

How It Drives

To demonstrate how it works, Chevrolet attached a secondary display to the truck and then sent us out on the test track at GM's Milford Proving Grounds to try it out.

2019 Chevrolet Silverado 1500 Rear End

The 5.3-liter feels natural mated to the eight-speed automatic, and shifts are as smooth in this truck as they are in the 2.7-liter turbo we also sampled. Additionally, it's apparent after driving just 100 feet that this new truck is significantly lighter than the current generation.

What's as impressive as the weight reduction is how seamlessly the DFM system works. If it weren't for a digital readout showing the fraction mode the computer was in (1/3, 5/9, etc.), you'd have no idea that the system was working.

The system responds rapidly to changes in throttle input. You might be running on two or three cylinders and put your foot down. It immediately is in V-8 mode with no noticeable lag. If you didn't know any better, you'd just think your V-8 was always running in V-8 mode.

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GM has been building small-block engines since 1955 but continues to find ways to optimize and enhance them with the latest technology. Dynamic Fuel Management is the latest of those advancements.

We should get towing and payload performance numbers soon, along with EPA fuel-economy estimates. Although our time driving was brief, we walked away impressed with the 5.3-liter V-8 and are look forward to seeing how it holds up when subjected to the rigors of real-world testing in a few months when it hits dealerships.

Manufacturer images

Factory 10-Speed for the 6.2-liter V-8

2019 Chevrolet Silverado 1500 10-Speed Transmission

Factory Eight-Speed for Everything Else

2019 Chevrolet Silverado 1500 8-Speed Transmission

 

Comments

@papa
My car engine F150 5.0 had no problems pulling a 7000 travel trailer over hill and dale in PA. I’m sure a 5.3 would have performed about the same.

@ Grnzel

Totally agree with u! The 5.0L is looking to be a good motor for Ford. Hopefully they keep it around for the 19+ years the 5.3L has been around. They need to have not comparisons between these 2 motors.

Thanks all for the practical info and options on greasing the spline. I intend keeping my sierra 1500 a long time so I will take all your suggestions, including doing more research on utube.

@Jhawk

If you have a floor jack and stands, couple of cold beers, a little tub of wheel bearing grease, a socket set and 45 minutes to spare, you can probably grease your splines with no sweat. Plastic gloves optional.

@ Frank

Do u read. This engine was built from the ground up for trucks!!!! Your ecoboosts were not built for trucks. They first appeared in cars and SUVs. What is so hard for u to understand? Or are u just upset that this little 4 cylinder makes more power than your 2.7L ecoboost V6 car engine?

Posted by: TNTGMC | May 18, 2018 5:57:56 PM

Dude, just stop already. Think before posting non-sense, you're no engineering to say which FORD engine is adequate for a Car/Truck.

Please....goodbye.

It's not nonsense. Think before u post! U embarrass yourself

The ecoboost was in a car and SUV before a truck

GM built this from ground up....read others postings on this. Your a day late and dollar short like always

You think some of those "hard downshift" issues are still related to the "clunk" all these trucks can exhibit due to driveshaft vertical movement on output shaft of trans? I know I have had times when coasting and unloading the driveshaft results in a clunk when stepping it back down and downshifting. Greasing the spline made that go away but the average truck buyer nowadays doesn't really get that in depth.
Posted by: andrwken | May 19, 2018 9:11:05 AM

Yep slip yoke is a big one. It's more common in the last 4 or 5 years due to GM and Ford using a grade braking feature in the transmission to boost city fuel economy. See below.

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@andrwken & Brick, thank you for your posts my truck displays the symptoms you both describe. Forgive but, I am not a mechanic what exactly is greasing the spline? Can you tell us more about that? Could a dealership provide this service? Thanks guys.
Posted by: Jhawk | May 19, 2018 12:28:51 PM


Just like others have said, all you need to do is lubricate the slip yoke. All solid rear axle trucks with a leaf spring suspension exhibit something called axle wrap as the truck accelerates or decelerates. GM and Ford updated their 6-speeds at some point in the last few years to keep the torque converter clutch locked up at low speeds, even when you're foot isn't on the accelerator pedal. As you coast, you might have noticed that it feels like you're engine braking. Sometime the transmission will even exhibit a hard or firm downshift and a clunk. The clunk is the caused by the slip yoke and rear axle loading and unloading. Older automatics didn't do this because they typically let you coast freely, so the axle, slip yoke, leaf springs etc weren't being loaded and unloaded on decel.

Newer trucks use the transmission to recapture energy from your forward motion to help turn the engine while you decelerate. By doing this, the engine doesn't need to burn fuel to keep the engine turning as well as driving the alternator, ac compressor, water pump, etc. It also helps extend brake lift. The downside is that it causes the axle to wrap and unwrap. If the slip yoke doesn't slide smoothly and freely, pressure begins to build on the yoke until it finally slides, making a clunk. Sometimes a firm downshift will be accompanied with a clunk, which is the SY and axle moving.

It is possible to deactivate this engine braking feature, which helps eliminate this 99% of this clunk. It's called grade braking (not the same thing as hill descent brake assist).

***If you grease your slip yoke, make sure whatever you use is compatible with the fluid in your transfer case. GM and Ford have issued TSB's on slip yoke clunk that specify the best grease for the job. Some lubricants can cause issues with the wet clutch that transfers power to the front wheels in AWD mode. Clutch slip is electronically controlled and a change in friction due to fluid contamination could cause issues. (GM 2014+ halftons currently use the MP3023/24 aka NQH transfer case)

The leaf springs will also make noises if they're dirty enough to cause the secondary leafs to not slide smoothly against the bottom of the main leaf. They'll begin to creak and clunk as the plastic slides stick momentarily, then suddenly break free. If you think your leaf springs are doing this, pressure wash the leaf springs to get the dirt and grit out from under the plastic pads. You can also apply a dry lube that contains PTFE (Teflon) or graphite to help them slide smoothly. Also check the brackets that keep the secondary leaf aligned with the main leaf. They get dirty and create noise too. Do not use grease on leaf springs - it attracts dirt and sand, which will cause noise to eventually come back worse.


My 2014 Silverado doesn't make clunking noises. It did downshift very firm when it was new but that went away by the first oil change. I did have leaf spring creaking and popping noise after messing with my suspension but after pressure washing and lubricating with AC Delco Superlube teflon spray, I haven't had it come back since.

@brick

I don't know who makes GM's leaf springs (maybe GM!) but mine were noisy until I hassled the dealer into cleaning it up.

They explained that the springs are covered with something kind of like old fashioned under-coating.

The sticky black goop makes the springs noisy. The service dept played with them for a day or so and when I got the truck back it was superb. Still is almost 10 years later.

I didn't notice any black goop on mine. Just a really slick black semi-gloss paint.

Sounds like GM's part supplier used something similar to cosmoline back then to prevent the leaf springs from rusting during shipment and workers left the coating on during assembly? I could see something like cosmoline attracting dirt and causing a lot of noise.

GM once again as always, GM brings totally new tech to the truck market, mean while Ford keeps use 1960s tech. LMBO!!!!!!!!!!!!!! Hey Ford, your 50 years late!

What I want to buy is a new motor controller with active fuel management and a 8 speed transmission for my S2000 Honda
More power than the pis-ant 4 cylinder Honda motor and better MPG

Smile

P.S. Please let me know if it will be available with displacement on demand for other cars?

A universal marketing problem is that individuals always hate new ideas, sometimes because they can't afford to be early adapters and sometimes because they fear the untried and unknown. Look at how Toyota got lashed over hybrid power trains. Today the prius has the largest share and every automaker in the world is making hybrids and all electrics. The reduction in moving parts for an all electric is a full order of magnitude. If we can continue to get the power and torque of a big engine with improved fuel economy we should rejoice and stay tuned to the future.

@Douglas Allen

thanks for your point of view. Here's another thought. Humans spent trillions of dollars and 100 years to develop the motoring infrastructure we have today. Unplugging the fossil fuel "eco-system" of fossil fuel supply chains and other business relationships is not as simple as just building and buying new all electric cars. It's a process that will take decades---and for what? There is considerable and scientific debate over the issues surrounding the potential threat (if any) of greenhouse gas. Energy independence and even individual responsibility for our own lives is another matter.

Until the world's electrical generating capacity moves to a non polluting alternative the green calculation does not work for electric cars.

papajim, don't worry, AOC has a plan to eliminate ALL fossil fuels and save us from our otherwise certain death's in 12 years. We can't afford not to implement her $60 trillion plan to save the planet, so no reason to worry about the cost.

@Texas...

Do you remember how the libtard media flipped out when Sarah Palin jokingly said she could see Russia from her back window? As soon as she said it Saturday Night Live rehearsed it and Tina Fey memorized the part.

We can presume that Tina won't be warming up her Palin routine this week, right?



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