By on January 25, 2019

2019 Chevrolet Silverado

General Motors’ Spring Hill, Tennessee assembly complex has reason not to worry about the automaker’s current round of cost-cutting and plant mothballing. There’s not a car in sight.

On Thursday, the General forked over another $22 million to facilitate production of a thriftier version of its revered 6.2-liter V8 truck engine, which brings total investment in Spring Hill to over $2 billion this decade alone. 

Spring Hill added 6.2-liter V8s to its propulsion mix back in 2016, but this version of the mill adds Dynamic Fuel Management for increased fuel economy. Destined for GM’s Silverado/Sierra twins and full-size SUVs, the engine shuts off cylinders in 17 different patterns, depending on engine speed and load. Under certain conditions, said trucks can make headway on the strength of one cylinder.

DFM joins the automaker’s tech grab bag for 2019; 5.3-liter V8s see it, as well. If you’re curious about DFM’s method of operation, GM explains it here:

An electromechanical system deactivates and reactivates all 16 of the engine’s hydraulic valve lifters, controlling valve actuation. The system uses solenoids to deliver oil pressure to control ports in the lifters, which activate and deactivate the lifters’ latching mechanisms. When a cylinder is deactivated, the two-piece lifters effectively collapse on themselves to prevent them from opening the valves. When the cylinder is reactivated, solenoids send an oil pressure signal to the control ports on the lifters and the latching mechanism restores normal function, allowing the valves to open and close.

Vehicles rolling out of Spring Hill, once home to the Saturn lineup, include the GMC Acadia and Cadillac XT5, but 2019 brings a new occupant. Funded by a $300 million cash dump, Cadillac’s edgy-in-the-front, bland-as-hell-in-the-back XT6 crossover goes into production later this year, filling a glaring gap in the brand’s lineup. That vehicle should add a further 200 jobs to the plant, which currently employs about 3,800 workers.

Is there a better recipe for job security than big truck engines and midsize crossovers?

While it’s high times at Spring Hill, other North American plants can’t say the same. Late last year, the automaker announced it would cut off the flow of product heading to Detroit-Hamtramck, Lordstown, and Canada’s Oshawa Assembly. Two transmission facilities in Michigan and Maryland also stand to close in 2019.

Oshawa’s closure looks like a done deal, but the fate of the company’s Detroit and Ohio facilities hinge on UAW contract negotiations taking place this summer.

[Images: General Motors]

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19 Comments on “This GM Plant Isn’t Unhappy...”

  • avatar
    Car Ramrod

    It does appear to be good times in Spring Hill, where the construction of moderately priced homes on the Maury County/ Williamson County line where the plant is located continues at a pace that may be even higher than a year or two ago. Between the lower taxes south of the county line for Nashville commuters and the plant’s growth the town continues to expand rapidly, this news just adds more fuel to that fire.

  • avatar

    Sounds good!

    Not so fast. DFM sounds like a lot of tech to me, for a very minor MPG gains.

    If the truck develops DFM issues when it’s 5 or 10 years old, the repair bill will more than exceed the ‘fuel saved’ before.

    But GM (and the rest) things like this, and 10-speed trannies, for incremental gains on the EPA MPG cycle, to comply with the law.

    Is it worth it? The added cost to engineer and manufacture this stuff? The cost to FIX it later? Or do the automakers hope this stuff will last the life of the car?

    Glad Spring Hill economy is ‘booming’. Sounds like area would have done well even if the old Saturn plant had stayed closed. Any word on what is happening with GM’s downsizing in Detroit area?

    • 0 avatar

      Generically these techs are often lumped under the banner “Active Fuel Management” (AFM) and I’ve seen too many mechanics shake their heads and say things like “I LOVE AFM because that means you’ll be coming to see me eventually.”

      Fortunately on some vehicles doing something like selecting the “sport” mode turns it off – like on a V8 Charger/Challenger.

      I gives me pause on vehicles like the V6 Lacrosse (the only application of the 3.6 V6 that has a cylinder deactivation feature.)

    • 0 avatar

      Even “bulletproof” Honda has screwed up their VCM system. Once your V6 is out of warranty, there’s a much higher chance of an expensive repair. But, see, this is just job security for Honda dealership mechanics. Or for engine assembly plant workers.

  • avatar
    Middle-Aged (Ex-Miata) Man

    From the colossal f-up that was the V8-6-4 in the Eighties and continuing today with GM’s ongoing woes with its other cylinder deactivation/AFM applications, consumers have ZERO reason to believe the company will be able to successfully implement this tech on the otherwise fantastic 6.2L.

  • avatar

    I thought GM changed the DFM so that it no longer can run on one cylinder, it has to be a minimum of two.

    Maybe they can set the timing up like a V-twin so that it sounds like a Harley waiting at a stoplight :)

  • avatar

    Don’t want to sound snarky but I have visions of V8-6-4 going off in my head. “No, I insist, after you; I’m right behind you…..”

  • avatar
    Gardiner Westbound

    Automakers are stuffing vehicles with unproven and expensive to fix technology. Overwrought engineering, bleeding edge electronics and hugely complex transmissions need time to mature. Let the morons with deep pockets take the enormous financial hit when they fail.

  • avatar

    I drove a 2008 Silverado with AFM (ACTIVE Fuel Management). On the highway, if I tried very hard, I could discern when the engine went from 4 to 8 cylinders–shortly before, it would slightly vibrate (as if to say, ‘it’s too much for 4’, but it was very slight, I had to focus to perceive it). If I recall correctly (it’s been a while), gentle highway driving (50-65mph) tended to bring out the 4-cyl mode when not going up a grade. That probably enabled the truck to exceed 20 mpg at these speeds (I could get 20-plus mpg over a few miles per the computer if the cruise was set at 63mph )

    So, the 4 cyl mode probably did get 1-2, maybe 3 mpg more at 50-60mph speeds. But most highway driving is 65-80. So whatever fuel I save, I’d pay back if the system developed a problem. Probably pay more in repairs.

    It was not annoying. I don’t know what happened to that truck, or if it had any AFM issues. I think (but not sure), AFM allowed engine to go from 8 to 6 to 4 cylinders.

    DFM allows more variability…from 1 cylinder to 8. 1 cylinder? Really?

    This sounds more complicated. They both sound complicated.

    That said, I don’t think GM owners have had big problems with it. If they had, in this era, we would know of it.

    But, ‘not big problems’ is not the same as ‘no problems’. I’m sure AFM/DFM or 10-speeds have more opportunities to break than NO AFM/DFM or a 6-speed. And they cost less up front. That’s all I’m saying (not that AFM/DFM are lemons).

    • 0 avatar

      My G8 GT was fairly noticeable in V4 mode as well, and the transition wasn’t the smoothest.

      RAM’s way around this on their new trucks is to add an active damper on the chassis (kinda like active noise cancellation) so that it could stay in V4 mode longer without the users noticing. GM’s solution is to vary which cylinders are shut down, which I think is a bit more elegant. In both cases, it lets the trucks stay in reduced-cylinder mode longer for better fuel economy.

  • avatar

    I had issues with the DFM in our Yukon XL Denali. There was a really noticeable transition between the 4 and 8 cylinder modes, especially at lower speeds.

    After a dealer visit and a flash, no issues. It’s seamless now.

  • avatar

    I’ve rebuilt a couple engines with cylinder deactivation, and I can see where this is going to affect the second and third owners of trucks. These systems all require low viscosity oils and are more sensitive to contaminated oil. People have gotten used to a couple decades of good enough build quality that they shouldn’t have to check the oil levels very often, or even not having the option to check because a sensor is supposed to do the work for you. I’m not looking forward to the used market in 10-15 years.

    • 0 avatar

      Thanks for the insight binksman.

      THAT makes sense. I don’t check my oil as diligently as I did 30 years (but maybe it’s because I don’t love my cars now as much as I used to…)

      So, what do you anticipate happening? Is this a MUST repair item? It sounds like it. How much would it cost to correct?

      • 0 avatar
        Jeff Weimer

        I don’t check or change my oil as diligently as I did 20 or 30 years ago because I rely on my oil monitor, even though I change it at “20%” instead of waiting for the alert at 15%.

        I always thought the “3000 mile rule” was just a full-employment-for-mechanics-and-motor-oil-companies scheme anyway. I usually did 5000-6000 mile oil changes.

  • avatar
    Michael S6

    My S6 has a highway 4cylinder mode, and cruising at 55-65 mph can get up to 28 mpg which is not bad for 4400 lbs awd car. I could never tell if it goes into 4 cylinders mode and Its impossible to tell how much fuel it saves.

  • avatar

    Wow, that is one cheap looking interior.

    • 0 avatar

      Can you see anything at all out of that rearview mirror?

      Not only is that thing shaped like the facial expression of a demented clown (which seems to be a pathological obsession in the auto industry), but the thing looks smaller than those old mirrors in GM cars pre-OnStar that had the built-in map lights. Meaning that you can only see about half of what’s behind you!


  • avatar

    I would not be surprised if there is a tune available soon from most of the aftermarket tuners that disables AFM variants on these trucks. I know that I’d buy it!

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