Editing Active Fuel Management

{{Short description|Trademarked variable displacement technology}}
{{for|other similar systems|variable displacement}}

'''Active Fuel Management''' (formerly known as '''displacement on demand''' ('''DoD''')) is a trademarked name for the [[car|automobile]] [[variable displacement]] technology from [[General Motors]]. It allows a [[V6]] or [[V8 engine]] to "turn off" half of the cylinders under light-load conditions to improve [[Fuel economy in automobiles|fuel economy]]. Estimated performance on [[United States Environmental Protection Agency|EPA]] tests shows a 5.5–7.5% improvement in fuel economy.<ref>{{Cite web|url=https://www.sae.org/publications/technical-papers/content/2007-01-1292/|title=Active Fuel Management Technology: Hardware Development on a 2007 GM 3.9L V-6 OHV SI Engine|first1=Mark|last1=Stabinsky|first2=William|last2=Albertson|first3=Jim|last3=Tuttle|first4=David|last4=Kehr|first5=James|last5=Westbrook|first6=Henning|last6=Karbstein|first7=Mario|last7=Kuhl|date=April 16, 2007|doi=10.4271/2007-01-1292 |via=www.sae.org}}</ref>

GM's Active Fuel Management<ref>{{Cite web|url=https://gmauthority.com/blog/gm/general-motors-technology/general-motors-propulsion-technology/general-motors-active-fuel-management-cylinder-deactivation-technology/|title=General Motors Active Fuel Management Cylinder Deactivation Technology|website=GM Authority|date=30 November 2017 }}</ref> technology used a solenoid to deactivate the [[Tappet|lifters]] on selected cylinders of a [[Valvetrain|pushrod]] V-layout engine.

GM used the Active Fuel Management technology on a range of engines including with the GM Small Block Gen IV engine family, first-generation GM EcoTec3 engine family, second-generation GM High-Feature V6 DOHC engine family, and first-generation High-Feature V8 DOHC engine family. Vehicle applications included the 2005 Chevy TrailBlazer EXT, the GMC Envoy XL, Envoy XUV, and [[Pontiac Grand Prix]].

==Displacement on demand==
[[General Motors Corporation|General Motors]] was the first to modify existing production engines to enable cylinder deactivation, with the introduction of the Cadillac [[Cadillac V8 engine#V8-6-4|''L62'' "V8-6-4"]] in 1981.

==Second generation==
In 2004, the electronics side was improved greatly with the introductions of Electronic Throttle Control, electronically controlled transmissions, and transient engine and transmission controls. In addition, computing power was vastly increased. A [[solenoid]] control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylinders [https://web.archive.org/web/20061029082032/http://www.gm.com/company/onlygm/fuel/engine.html]. Unlike the first generation system, only half of the cylinders can be deactivated. It is notable that the second generation system uses [[engine oil]] to hydraulically modulate engine valve function. As a result, the system is dependent upon the quality of the oil in the engine. As anti-foaming agents in engine oil are depleted, air may become entrained or dissolve in the oil, delaying the timing of hydraulic control signals. Similarly engine oil [[viscosity]] and cleanliness is a factor. Use of the incorrect oil type, i.e. [[Society of Automotive Engineers|SAE]] 10W40 instead of SAE 5W30, or the failure to change the engine oil or oil filter at factory recommended intervals, can also significantly impair system performance.{{Citation needed|date=April 2008}}

In 2001, GM showcased the 2002 [[Cadillac Cien]] [[concept car]], which featured [[Cadillac Northstar engine|Northstar]] XV12 engine with Displacement on Demand. Later that year, GM debuted [[Opel Signum]]² concept car in [[Frankfurt Auto Show]], which uses the global XV8 engine with displacement on demand. In 2003, GM unveiled the [[Cadillac Sixteen]] concept car at the Detroit Opera House, which featured an XV16 concept engine that can switch between 4, 8, and 16 cylinders.

On April 8, 2003, General Motors announced this technology (now called Active Fuel Management) to be commercially available on 2005 [[GMC Envoy]] XL, Envoy XUV and [[Chevrolet TrailBlazer]] EXT using optional [[GM small-block engine#5300|Vortec 5300]] V8 engine. GM also extended the technology on the new [[GM High Value engine#LZ8|High Value ''LZ8'']] V6 engine in the [[Chevrolet Impala]] and [[Chevrolet Monte Carlo|Monte Carlo]] as well as the 5.3L V8 LS4 engine in the last generation Chevrolet Impala SS, Monte Carlo SS and Pontiac Grand Prix GXP.  In both designs, half of the cylinders can be switched off under light loads.

On July 21, 2008, General Motors unveiled the production version of the [[Fifth-generation Chevrolet Camaro|2010 Chevrolet Camaro]]. The Camaro SS with an automatic transmission features the [[GM LS engine#L99|GM L99]] engine, a development of the [[GM LS engine#LS3|LS3]] with Active Fuel Management which allowed it to run on four cylinders during light load conditions.<ref>[http://paultan.org/archives/2008/07/23/2010-chevrolet-camaro-details-and-hi-res-photos/ 2010 Chevrolet Camaro Details and Hi-Res Photos]</ref>

==Third generation==
In January 2018, GM announced an improved version of AFM called ''Dynamic Fuel Management'' to be initially released in Chevy Silverado trucks. This system shuts off any number of cylinders in a variety of combinations, maximizing fuel economy and avoiding switching between banks of cylinders.<ref>{{cite web
 | url=http://www.gm.com:80/mol/m-2018-jan-0113-2019-silverado.html
 | archive-url=https://web.archive.org/web/20180426022622/http://www.gm.com/mol/m-2018-jan-0113-2019-silverado.html
 | url-status=dead
 | archive-date=2018-04-26
 | title='19 Silverado may emerge as efficiency leader
 | access-date=2018-02-21
 }}</ref><ref>{{cite web
 | url=http://www.gm.com:80/mol/m-2018-jan-0113-2019-silverado.html
 | archive-url=https://web.archive.org/web/20180426022622/http://www.gm.com/mol/m-2018-jan-0113-2019-silverado.html
 | url-status=dead
 | archive-date=2018-04-26
 | title=Introducing the All-New 2019 Chevrolet Silverado
 | access-date=2018-02-21
 }}</ref> This is achieved by using oil pressure solenoids to collapse each individual hydraulic valve lifter, allowing for fully independent individual cylinder control. The system is based on ''Dynamic Skip Fire,''<ref>{{Cite journal|url=https://www.sae.org/publications/technical-papers/content/2013-01-0359/|title=Design and Benefits of Dynamic Skip Fire Strategies for Cylinder Deactivated Engines|first1=Mark|last1=Wilcutts|first2=Joshua|last2=Switkes|first3=Mark|last3=Shost|first4=Adya|last4=Tripathi|date=April 8, 2013|journal=SAE International Journal of Engines|volume=6|issue=1|pages=278–288|via=www.sae.org|doi=10.4271/2013-01-0359|url-access=subscription}}</ref> a technology developed by California company Tula Technology.<ref>{{cite web|url=https://www.sae.org/news/2018/05/gm-2019-v8s-with-dfm-system|title=GM adopts advanced cylinder deactivation for 2019 Chevy Silverado V8s|last=|first=|date=|website=|access-date=}}</ref> The [[General Motors LS-based small-block engine#L86/L87|6.2L V8 engine]] of the Chevrolet Silverado incorporating the technology was named one of [[Ward's 10 Best Engines]] for 2019.<ref>{{cite web | url = https://www.wardsauto.com/2019-10-best-engines/2019-winner-chevy-silverado-62l-ohv-v-8-dfm |title=2019 Winner: Chevy Silverado 6.2L OHV V-8 with DFM}}</ref>
==See also==
* [[Variable displacement]]
* [[Honda]]'s [[Variable Cylinder Management]] (VCM)
* [[Chrysler]]'s [[Multi-Displacement System]] (MDS)
* [[Daimler AG]]'s [[Active Cylinder Control]] (ACC)
* [[Start-stop system]]
* [[Cadillac V8 engine#V8-6-4|Cadillac Variable Displacement V8-6-4 L62 Engine]]

==References==
{{Reflist}}

==External links==
* [http://www.acarplace.com/brands/gm/xv8-engine.html XV8 concept engine]
* [https://web.archive.org/web/20050407145028/http://www.caddyinfo.com/xv12.htm XV12 concept engine]
* [https://archive.today/20020219041149/http://media.gm.com/news/releases/010912opelsignum.html Opel Signum² press release]
* [https://web.archive.org/web/20221127120201/https://www.greencarcongress.com/2005/11/gm_expands_depl.html GM Expands Deployment of Displacement on Demand]
* [https://web.archive.org/web/20130602072249/https://www.greencarcongress.com/2005/12/gms_dod_now_cal.html GM’s DoD Now Called “Active Fuel Management”]

[[Category:Engine technology]]
[[Category:Automotive technology tradenames]]