MAP sensor VS MAF sensor

jinkl

4,000 RPM
Senior Member

jinkl

4,000 RPM
Senior Member
May 22, 2004
4,625
376
3,183
Kuala Lumpur
This are the two systems used on EFI's rite
what are the pro and cons of MAF and MAP
 

taqu

Known Member
Senior Member

taqu

Known Member
Senior Member
Dec 17, 2004
207
1
3,018
Visit site
There're actually 3 air metering ways :

1. AFM - airflow meter
2. MAF - mass airflow
3. MAP - manifold absolute pressure (or speed/density)

I'm no expert so I'll just give some link : Understanding the benefits of MAP

Some copy-paste from http://www.teglerizer.com/fi/bem/Basics%20...0management.htm

Engine load

Engine load is normally determined by one of the following methods

Throttle Position Sensor (no measuring of airflow at all)

The most common engine load sensor especially on after market systems. A TPS is a small potentiometer (or ‘throttle pot’) which is connected directly to the throttle shaft and turns with it. It returns a value to the EMS depending on the throttle position. TPS sensors are normally used on performance engines where airflow sensors might become confused because of pulses in the inlet tract, because they do not measure airflow but simply give a throttle position, airflow is assumed to be constant for any given engine speed and throttle position. If the engine is further modified the airflow characteristics may change and the engine may need re-mapping. EMS systems that use direct airflow measurement can often cope with changes more effectively and can alter the fuelling to suit without a re-mapping session.

Air metering flap (AFM)

Another way of determining the engine load is to measure the airflow into the engine and this can be done using a flap which is deflected by incoming air, this is commonly known as an airflow meter. These are common on older injection systems, but can be confused by reverse pulses in the inlet tract when more extreme cams are used and can be restrictive to the inlet airflow.

Manifold Air Pressure sensor (MAP)

These measure the vacuum or air pressure in the inlet manifold that in turn gives an indication of load, more commonly used on turbocharged engines to give an indication of boost level. This is often referred to as a MAP sensor, although not to be confused with a map.

Hot wire (MAF)

This approach uses a heated platinum wire and measures the current required to keep it at a particular temperature. As air passes over the wire it cools it down, the more air that passes, the greater the cooling effect and therefore the greater the current. The hot wire system can be also be confused by reverse pulses when more extreme cams are used.
 

boggysv

2,000 RPM
Senior Member

boggysv

2,000 RPM
Senior Member
Sep 7, 2004
2,025
4
3,138
Not to forget there is alsothe vortex flow sensor (very rare), which uses an ultrasonic sender and receiver to measure the rate at which vortices pass through the control passage.

Another way of saving cost is just use manifold vacuum level and engine RPM to determine fueling needs.
 

zaki

Known Member
Senior Member

zaki

Known Member
Senior Member
Dec 7, 2003
328
0
3,016
Kuala Lumpur
Originally posted by boggysv@Feb 2 2005, 00:02
Not to forget there is alsothe vortex flow sensor (very rare), which uses an ultrasonic sender and receiver to measure the rate at which vortices pass through the control passage.

Another way of saving cost is just use manifold vacuum level and engine RPM to determine fueling needs.
but it's quite common with most mitsu & proton cars...
 

Joeker

Walking Dead
Senior Member

Joeker

Walking Dead
Senior Member
Nov 19, 2003
3,581
62
3,148
Jinjang
Visit site
Standalone engine management system uses MAP metering devices to replace MAF sensors for better airflow