On 86 - 88 cars 'Air Density" cars,.. the top circle is a MAP sensor on those models. They do not have a MAF meter.



The second image is the engine bay of an 88 GT. As you can see,.. it has the same casing for the BAP,.. but here it is a MAP sensor. You can also see that there is no MAF meter.

If you ever convert your 86 - 88 from Air Density to MAF. Part of the conversion process is to leave the MAP sensor wired up and powered,.. but the vacuum line is disconnected and plugged off. It then becomes a BAP.

I'm not an expert here.. but hopefully I can explain the difference in laymans terms.

Air Density the ECM uses a preset table for the Air/Fuel. The most of the engine management is done through the MAP sensor which reads manifold vacuum,.. then the Throttle Position Sensor (TPS) and then the O2 sensors which are mainly there to signal ignition advance controls. Basically it says at 3000 RPM there should be a preset amount of air entering the engine and it will signal the injectors to pulse a preset amount of fuel. No more,.. no less.

Starting in 1989,.. (1988 for California cars) Ford started using MAF (Mass Air Flow) meters. It has a heated wire,.. and depending on how much air passes over it will change the voltage signal to control the injectors and the ECM knows how much air is entering the engine and will pulse the injectors accordingly. It is still reading manifold vacuum,.. but it does not have as much effect on engine management as it did when it was Air Density. Which is why MAF cars are much more friendlier to cams, intakes and other modifications then an AIR Density car will be.

I'm sure I'm leaving a lot out. I'm no EFI expert,.. I know more about the 4.6 engines then the EFI 5.0 engines. I usually convert 5.0 EFI over to Carb when I buy one. That 88 is one of the few that I owned that stayed EFI.


Hurst