air flow sensor instead of injector signal?
 

hi

would it not be simpler to use the air flow sensor instead of injector signal? the air flow sensor gives a simple 0-5v output Dependant on flow and this is proportional to fuel used because of the ECU keeping the fuel/air ratio constant. people could buy another air flow meter and stick it on their air inlet. 0-5v is easier to data log and display than pulse width modulation. now if only i could find a speed sensor that gave 0-5V as well?

perhaps an electric motor turned by the wheels with a bridge rectifier?

There are applications (carburetors) that may want to utilize to such an approach, but there are issues that make the injector/vss a good choice.

1. Accuracy. The injector monitoring is proving to be very accurate (knock on wood). Because the car computer takes in many sensors it cannot be as accurate to just monitor airflow. It has to consider pressure/air temp/coolant temp/etc.

2. Universalness. All electronic fuel injected cars can have their injectors monitored with a mpguino. Not all fuel injected cars have the same types of sensors and not all sensors have the same calibration, so you wind up with a lot of complicated instructions just to get the hardware hooked up. It is complicated enough just getting two signals out of the car(injector and vss).

3. Completeness. It is fully functional. Not going to change oars now. Though airflow is still a serious consideration for the carburetor engines, fuel flow would be even better.

4. Cost. Tapping into an injector signal cost nothing, takes no space, and requires only electrical skillz (or good instructions from someone who has already been there). Adding a flow meter will make for plumbing skills and additional costs.

So I'm still keeping my options open for carbs, but fuel injectors are pretty much a done deal.