Editing AFM (section)

==[[ECU]] mapping of the AFM==

The measurement of voltage from the [[R31]] [[RB30E]] AFM is within the range from 2-4 volts.

It also happens that the Z31 AFM shares the same characteristic. Later model [[Nissan]]s ([[R32]], Z32, S13 etc) have a voltage range from 0 - 5 volts.

This makes the replacement of AFM a difficult task as the voltage range needs to be restricted in hardware rather than software.

[[Image:Afm8.JPG]]

The voltage range is measured inside the [[ECU]] as a non-linear map, called the Voltage Quantifier (VQ) map. 
This consists of typically 64 values (not necessarily this many for all [[Nissan]] [[ECU]]s).

This map determines what voltage measurement in terms of % of voltage from AFM maps to what scaling value.

There are formulas for this but that wont be covered here.

My current program - Nisemu below demonstrates how the mapping is displayed.

When a demo version is available you will be able to change this.

Other vehicles where an AFM upgrade is beneficial (and more possible) can be done, for example a Z32 AFM on an [[R32]] [[ECU]].

But this requires remapping of the [[ECU]] for this map.

Fortunately this is fairly trivial, since the VQ map from another [[ECU]] (such as Z32) can be taken and written over the top of the original.

Some people/companies charge a lot of money for this procedure.

It is currently possible with a $12 EPROM chip, $2.50 socket and EPROM programmer using ROM Editor.

[[Image:Afm9.JPG]]

VQ Map adjustment in Nisemu (under development)