MAFless tuning is a method of operating the fuel injection system on a gasoline-powered motor vehicle whereby the mass airflow meter, or MAF, is removed.
Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector.
The MAF is a component in a vehicle's intake system through which air flows past a wire that is heated by an electric current. The airflow cools the wire, enabling the MAF to calculate the mass of airflow into the engine. The vehicle's engine management computer then uses this information to calculate the correct amount of fuel to be delivered to the cylinders by the fuel injection system.
When tuning a MAF-equipped vehicle to operate in MAFless mode, the MAF is removed. This requires the use of an alternative method of calculating airflow into the engine, which is also referred to as 'Speed-Density' system, as opposed to a MAF system. On vehicles so equipped, this alternative involves the use of a manifold absolute pressure, or MAP, sensor. The MAP sensor measures pressure in the engine's inlet manifold. When coupled with data regarding the engine's revolutions per minute, or RPM, and a table of volumetric efficiency over the operating range of the engine, the MAP sensor can be used by the engine management computer to calculate fuel requirements.
By changing the engine from MAF mode to MAFless/MAP mode, vehicle modifiers claim two advantages:
A potential disadvantage of converting an engine from MAF to MAFless mode is that where the MAP sensor is used to measure airflow, the corresponding fuel calculations must be performed by the computer based on tables of information programmed by the engine tuner. If other parts of the engine are subsequently modified with an effect on airflow through the engine, these fuel tables must be adjusted to match the revised engine hardware. As airflow is measured from the MAP sensor, turbocharger variations will affect the fuel flow measurement resulting in higher or lower fuel flow. Without MAF, monitoring of the airflow is very difficult, and so the chances of reproducibility of the desired performance in the field is much less. EGR with the feedback system and exhaust sensors are necessary to lower the chances of engine to engine variation in performance. By contrast, when operating in MAF mode the computer can automatically adjust its fuel delivery based on the airflow data generated by the MAF, even if other engine hardware is changed.
Another small disadvantage is as the engine wears, the mean vacuum is decreased. This 'fools' the MAP sensor into overfuelling. This is only a problem on very high mileage engines.
MAFless tuning is a popular modification in Australia for Holden vehicles powered by the General Motors LS1 Gen III 5.7 V8 engine. The genesis for MAFless tuning of the LS1 in Australia was the HSV GTS version of the Holden Commodore, which was factory fitted with a Callaway-developed C4B version of that engine running in MAFless mode. Rated at 300 kW, the C4B was the most powerful factory LS1 sold in Australia and created substantial credibility for MAFless tuning of LS1 V8s. Within days of the HSV GTS's release the CSV Veloce was on the Australian market with a 330 kW LS1 incorporating a MAFless configuration. The MAFless configuration was later dropped by HSV and subsequent cars have all had MAF's. MAFless tuned LS engine equipped vehicles never eventuated in the United States as the C5 Corvette with the same engine was always fitted with a MAF sensor. It featured a larger MAF sensor body than the ones installed in the Australian cars, to avoid any intake restriction issues and still deliver accurate injection at all times.
Holden, formerly known as General Motors-Holden, is an Australian automobile importer and former automobile manufacturer with its headquarters in Port Melbourne, Victoria. The company was founded in 1856 as a saddlery manufacturer in South Australia. In 1908 it moved into the automotive field, becoming a subsidiary of the United States-based General Motors (GM) in 1931, when the company was renamed General Motors-Holden's Ltd. It was renamed Holden Ltd in 1998, and General Motors-Holden in 2005.
The Holden Commodore is a medium to large sedan sold by Holden since 1978. It was manufactured from 1978 to 2017 in Australia and from 1979 to 1990 in New Zealand, with production in Australia ending on 20 October 2017. From 2018 the Holden Commodore is fully imported from Germany.
North American tuners (and also the Australian manufacturers & tuners Holden & HSV) of the LS1 tend to prefer retaining the MAF sensor, instead more simply overcoming intake tract restrictions by installing a MAF with a larger diameter body. In this way, precise fuel injection metering is still retained at all engine speeds and loads. Australian tuners in comparison, prefer to use the less precise method of MAFless tuning (see 'Disadvantages' section above), requiring the engine computer to use predetermined fueling tables, resulting in less finely tuned injection systems that cannot adjust for other variables or engine hardware changes accurately.
The Holden Monaro is a rear-wheel drive coupé and sedan that was produced by Holden between 1968 and 1977 and between 2001 and 2005. Three generations of the Monaro have been produced, with the last spawning a limited edition model (CV8-Z) to farewell the historic name.
Holden Special Vehicles (HSV) is the officially designated performance vehicle partner of Australian marque, Holden. Established in 1987 and based in Clayton, Victoria, the company modified Holden models such as the standard-wheelbase Commodore, long-wheelbase Caprice and commercial Ute for domestic and export sale. Over the years, Holden Special Vehicles had also modified other non-Holden cars within the General Motors portfolio, in very low volumes.
The LS based small-block engine is the primary V-8 used in General Motors' line of rear-wheel-drive cars and trucks. Introduced in January 1995, it is a "clean sheet" design with only rod bearings, lifters, and bore spacing in common with the longstanding Chevrolet small block V8 that preceded it as the basis for GM small-block V8s. The basic LS variations use cast iron blocks, while performance editions are all aluminium with cast iron cylinder liners.
Lean-burn refers to the burning of fuel with an excess of air in an internal combustion engine. In lean-burn engines the air:fuel ratio may be as lean as 65:1. The air / fuel ratio needed to stoichiometrically combust fuel, by contrast, is 14.64:1. The excess of air in a lean-burn engine emits far less hydrocarbons. High air–fuel ratios can also be used to reduce losses caused by other engine power management systems such as throttling losses.
Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.
A ram-air intake is any intake design which uses the dynamic air pressure created by vehicle motion to increase the static air pressure inside of the intake manifold on an internal combustion engine, thus allowing a greater massflow through the engine and hence increasing engine power.
The manifold absolute pressure sensor is one of the sensors used in an internal combustion engine's electronic control system.
In internal combustion engines, water injection, also known as anti-detonant injection (ADI), can spray water into the incoming air or fuel-air mixture, or directly into the cylinder to cool certain parts of the induction system where "hot points" could produce premature ignition. In jet engines it increases engine thrust at low speeds and at takeoff.
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.
An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps, and adjusting the engine actuators. Before ECUs, air-fuel mixture, ignition timing, and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means.
A throttle is the mechanism by which fluid flow is managed by the constriction or obstruction.
A heated air inlet or warm air intake is a system commonly used on the original air cleaner assemblies of carburetted engines to increase the temperature of the air going into the engine for the purpose of increasing the consistency of mixing of the air and fuel in order to reduce engine emissions and fuel usage.
The Holden Commodore (VE) is an executive car that was produced by the Australian manufacturer Holden from 2006 to 2013. It was the first iteration of the fourth generation of this Australian-made model. Its range included the luxury variants, Holden Berlina (VE) and Holden Calais (VE); utility models were included as the Holden Ute (VE).
The WM and WN series Holden Caprice are a line of full-size/executive cars produced by the Australian manufacturer Holden from September 2006 to October 2017, sold primarily in Australia and New Zealand. They were also exported in various guises to the United States, the Middle East, China and South Korea. The range debuted alongside the smaller VE series Holden Commodore, which the Caprice shares its "Zeta" platform with, on 16 July 2006 at the Melbourne Convention and Exhibition Centre.
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The Lucas 14CUX is an automotive electronic fuel injection system developed by Lucas Industries and fitted to the Rover V8 engine in Land Rover vehicles between 1990 and 1995. The system was also paired with the Rover V8 by a number of low-volume manufacturers such as TVR, Marcos, Ginetta, and Morgan.
Corsa Specialised Vehicles (CSV) is a small-scale automaker established in 1994 that is based in Mildura, Victoria, Australia. Its range consists of V8-engined high performance cars based on those produced by Holden.