about MAF sensors...

[svx-t]

is all subaru MAF sensors the same? or are they all different?

[DarknessofDeath]

you should do a search for that. i believe i read that there was a didn't subaru MAF you could swap in with.
i'm sure someone will bring that answer up

[oab_au]

Originally Posted by svx-t

is all subaru MAF sensors the same? or are they all different?

I guess that they are physically the same, but they are calibrated differently for the different capacity's that the different engines have.

It will probably make it run, but it won't give the same performance or economy.

Harvey.

[Trevor]

Originally Posted by oab_au

I guess that they are physically the same, but they are calibrated differently for the different capacity's that the different engines have.

It will probably make it run, but it won't give the same performance or economy.

Harvey.

This is a definitive statement. The components could well be exactly the same, with adjustments being taken care of within the respective ECU units.

Real evidence is called for.

[Manarius]

Originally Posted by Trevor

This is a definitive statement. The components could well be exactly the same, with adjustments being taken care of within the respective ECU units.

Real evidence is called for.

When it comes to the MAF sensors on Early Legacy's, it depends on the style of MAF and manufacturer. There were two types - JECS (black in color used on most Legacy's) and the Hitachi type (of Metal type used in the 1990 Models). On most SVX engine bays I've seen, the sensor is black indicating that a JECS sensor was used. I would assume, perhaps, that JECS sensors from Legacy's would be interchangeable with ones on SVX's. However, this is only speculation. Most likely, either sensor would work correctly, but if the sensor was not 100% compatible, the ECU would throw a code 49 for Improper Airflow sensor (at least, this is what the code is on the 1990-94 Legacy).

[oab_au]

The MAF sensor measures the mass air flowing through the sensor and assigns a voltage reading of between 0V and 3.8V, from no air flow to full air flow.

Obversely a MAF for a 1800cc engine, fitted to a 3300cc engine will read 3.8V at about 1/2 throttle. That is why we fit the 350Z MAF to the blown engines, it equates 3.8V to a higher air flow than the SVX one.

Harvey.

[Trevor]

Originally Posted by oab_au

The MAF sensor measures the mass air flowing through the sensor and assigns a voltage reading of between 0V and 3.8V, from no air flow to full air flow.

Obversely a MAF for a 1800cc engine, fitted to a 3300cc engine will read 3.8V at about 1/2 throttle. That is why we fit the 350Z MAF to the blown engines, it equates 3.8V to a higher air flow than the SVX one.

Harvey.

The element is purely resistive. The voltage stated is an arbitrary figure. An OEM ECU could be designed to accept any range of an appropriate voltage thus a standard unit could be applied in variable circumstances.

In the supercharged application quoted, it would have not been practical to modify the ECU. Furthermore an increase in airflow was involved, making an increased cross section desirable.

MAF measurement is usually achieved by heating with an electric current, a wire/gauze/grid whatever, which is suspended in the engine’s air stream. The wire's electrical resistance increases with the temperature, which limits electrical current flowing through a circuit. When air flows past the wire, the wire cools, decreasing its resistance, which in turn allows more current to flow through the circuit. As more current flows, the wire’s temperature increases until the resistance again reaches an equilibrium which is relative to airflow.

N.B. The amount of CURRENT required to maintain the wire’s electrical resistance is directly proportional to the mass of air flowing past the wire.

If air density increases due to an atmospheric pressure or temperature change, but the moving air volume remains constant, the denser air will conduct more heat from the wire, so that as a result, higher mass airflow will be indicated.

[svx-t]

well...thanks for all the info but...my main question is...
is all subaru MAF sensors the same? or are they all different?

meaning by will my 93 impreza MAF sensor work with my 92 SVX??

[Hocrest]

Someone has posted that it does work, but your top end is affected. Sorry, but I don't remember who it was...
I know that MAFs from most mid 90's Subaru's will fit and they look identical except for the color of the tag.

[oab_au]

Originally Posted by Hocrest

Someone has posted that it does work, but your top end is affected. Sorry, but I don't remember who it was...
I know that MAFs from most mid 90's Subaru's will fit and they look identical except for the color of the tag.

Yes, that is pretty much what I said back in my first post.

Harvey.

[Trevor]

Originally Posted by svx-t

well...thanks for all the info but...my main question is...
is all subaru MAF sensors the same? or are they all different?

meaning by will my 93 impreza MAF sensor work with my 92 SVX??

Harvey says they must be different. I say, that on a technical basis they could be the same.

Physical evidence in respect of physical size and fit, as well as electrical characteristics are required. If you have the two in question, you can decide on the physical aspects. Measure the resistance of both and make a comparison as a first option.

You could then fit the Impreza MAF and check the following, i.e. the standard figures which apply. I would first do a check with your existing unit in place and before removal, for obvious reasons.

With the engine idling, connector plugged in :-

Terminal number 1, should have 13 - 14 volts to ground.

Terminal number 4, should have 0.8 - 1.2 volts to ground.

When the engine in my car was revved with the car stationery, voltage rose from 1.1 to 3 volts.

Looking into the connector plug as if it were disconnected, with the catch uppermost, the pins are in a row numbered left to right. Pin 1 is therefore, at the left hand end.

I trust this will be of assistance. Trevor.

[svx-t]

thanks everyone..