MAFless Tuning
Encyclopedia
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.
The MAF is a component in a vehicle's intake system through which air flows past a wire that is heated by an electrical 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.
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.
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, and taking Australian motoring performance to a new level. The MAFless configuration was later dropped by HSV and subsequent cars have all had MAF's. The MAFless tuned car never happened in the USA as the C5 Corvette with the same engine was always fitted with an MAF. It featured larger MAF meters than the ones installed in the Australian cars.
However, tuners of the LS1
in North America tend to prefer retaining the MAF, instead overcoming intake tract restrictions by installing an MAF with a larger diameter body.
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
system on a gasoline-powered motor vehicle whereby the mass airflow meter, or MAF, is removed.
The MAF
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
system.
Removing the MAF
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. 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 throttle position, the MAP sensor can be used by the engine management computer to calculate fuel requirements.Advantages
By changing the engine from MAF mode to MAFless/MAP mode, vehicle modifiers claim two advantages:- The MAF may pose a physical restriction across the vehicle's intake tract, thereby reducing airflow into the engine. By removing the MAF this restriction is eliminated, potentially improving engine performance.
- By moving the airflow measurement sensor from the intake plumbing to a point closer to the cylinders, the time lag from air moving past the sensor to reaching the cylinder can be reduced, thereby improving throttle response.
Disadvantages
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.
Applications
MAFless tuning is a popular modification in Australia for HoldenHolden
GM Holden Ltd is an automaker that operates in Australia, based in Port Melbourne, Victoria. The company was founded in 1856 as a saddlery manufacturer. In 1908 it moved into the automotive field, before becoming a subsidiary of the U.S.-based General Motors in 1931...
vehicles powered by the General Motors LS1
GM LS engine
The GM LS engine family is an engine design intended as the only V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The LS series was a "clean sheet" design with little in common with the classic Chevrolet small block V8...
Gen III 5.7 V8 engine. The genesis for MAFless tuning of the LS1
GM LS engine
The GM LS engine family is an engine design intended as the only V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The LS series was a "clean sheet" design with little in common with the classic Chevrolet small block V8...
in Australia was the HSV GTS version of the Holden Commodore
Holden Commodore
The Holden Commodore is an automobile manufactured since 1978 by the Holden subsidiary of General Motors in Australia, and, formerly, in New Zealand. In the mid-1970s, Holden established proposals to replace the long-serving Kingswood nameplate with a smaller, Opel-based model...
, 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
GM LS engine
The GM LS engine family is an engine design intended as the only V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The LS series was a "clean sheet" design with little in common with the classic Chevrolet small block V8...
sold in Australia and created substantial credibility for MAFless tuning of LS1
GM LS engine
The GM LS engine family is an engine design intended as the only V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The LS series was a "clean sheet" design with little in common with the classic Chevrolet small block V8...
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, and taking Australian motoring performance to a new level. The MAFless configuration was later dropped by HSV and subsequent cars have all had MAF's. The MAFless tuned car never happened in the USA as the C5 Corvette with the same engine was always fitted with an MAF. It featured larger MAF meters than the ones installed in the Australian cars.
However, tuners of the LS1
GM LS engine
The GM LS engine family is an engine design intended as the only V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The LS series was a "clean sheet" design with little in common with the classic Chevrolet small block V8...
in North America tend to prefer retaining the MAF, instead overcoming intake tract restrictions by installing an MAF with a larger diameter body.