Eli87
01-27-2009, 02:13 PM
Greetings everyone,
I've recently got my cell running in my 1986 BMW 535i, I have started looking into installing an MAP/MAF Adjuster.
I have found this information on a BMW forum. MyE28.com
The air metering device on E28s is an AFM, not a MAF -- no E28s came stock with a MAF. While the objective is to end up with a measurement of the total amount (by mass) of air that is going in, the function and method of signal interpretation is entirely different.
An AFM is not a "mass flow device." Air flowing through the AFM causes a spring-loaded "flapper" door to deflect an amount proportional to the dynamic pressure of the flow. The AFM sends both flapper door angle and temperature to the ECU in separate signals. The ECU interprets the flapper door angle as dynamic pressure and combines this with the temperature reading to determine the mass flow.
A MAF is a "mass flow device." The ECU interprets the cooling of a heated wire element in the MAF to determine the mass flow. The lower the temperature, the greater the density, and/or the greater the volume passing over the heated element, the greater the cooling. Again, no E28s came stock with a MAF.
I could see the voltage change in the AFM sensors being very similar as MAF or MAP voltage change. My concern is that there are several sensors determining what the computer sees, and all the variability of that
So has anyone installed a MAP/MAF adjuster in a BMW with an AFM or an automobile with a similar air flow monitoring device. Or have any ideas on how to deal with something like this.
Any other tips or insight dealing with HHO and BMW's would be awesome.
Thanks, these forums are great and have help me greatly already.
-Eli
I've recently got my cell running in my 1986 BMW 535i, I have started looking into installing an MAP/MAF Adjuster.
I have found this information on a BMW forum. MyE28.com
The air metering device on E28s is an AFM, not a MAF -- no E28s came stock with a MAF. While the objective is to end up with a measurement of the total amount (by mass) of air that is going in, the function and method of signal interpretation is entirely different.
An AFM is not a "mass flow device." Air flowing through the AFM causes a spring-loaded "flapper" door to deflect an amount proportional to the dynamic pressure of the flow. The AFM sends both flapper door angle and temperature to the ECU in separate signals. The ECU interprets the flapper door angle as dynamic pressure and combines this with the temperature reading to determine the mass flow.
A MAF is a "mass flow device." The ECU interprets the cooling of a heated wire element in the MAF to determine the mass flow. The lower the temperature, the greater the density, and/or the greater the volume passing over the heated element, the greater the cooling. Again, no E28s came stock with a MAF.
I could see the voltage change in the AFM sensors being very similar as MAF or MAP voltage change. My concern is that there are several sensors determining what the computer sees, and all the variability of that
So has anyone installed a MAP/MAF adjuster in a BMW with an AFM or an automobile with a similar air flow monitoring device. Or have any ideas on how to deal with something like this.
Any other tips or insight dealing with HHO and BMW's would be awesome.
Thanks, these forums are great and have help me greatly already.
-Eli