Does anyone know how I can measure realtime fuel consumption on the DPFI system?

I did figure out how to measure fuel rate by tapping into the injector and reading the dwell rate but this isn't this is done only one injector at a time and doesn't measure fuel consumption.

Scangauges are only OBD2 specific and other DIY instrumentation usually only measures one injector and multiplies it by 4. Let me know if anyone has figured this out.

 

After it multiplies by 4, divide by 2? Maybe gettin inline flow rate guages for the pressure line and the return line?

 

Whoops forgot to say that with DPFI the injectors flow at different inconsistent rates. It's not as clear cut as with MPFI. Of course it adds fuel as needed but it seems like there is no method to the madness on which injector supplies how much and when.

So for this flow rate gauge I assume you put one on the return line and subtract that from the pressure line and you get your rate? In essence this will tell me the same thing as the dwell meter: How Much Fuel is being used at a precise moment. I'm looking to record how much fuel is being used over a certain amount of time. Kind of like a Fuel Odometer.

 

That is a complicated issue on older cars like ours.. There is no cheap or easy way to do it. I don't know of anyone who has done this using obd0 hardware, that is for sure, and even then definitely not with a pm5 ecu.

your best bet is to convert to obd1 and use an AEM EMS to gather the data, but that is a $1000 solution to a problem.

The other option is equally crazy, and to preface it, I am a programmer by day and wouldn't attempt it, but here goes anyway..

if you swapped the car to MPFI and then picked up an obd0 PM6 ecu, you can then have it chipped and essentially have full reign over what data you can gather from the hardware. Find the routine that performs the injector activation and have it output data on the serial bus about the injector pulse width (see the NG66 code base for the PM6 that is current which will unlock the factory serial bus). Then, from the serial bus, gather the data by modifying OpenECUControl to parse the output data correctly, and handle the injector pulse width / flow rate conversion to figure out exactly how much fuel is getting injected at any point in time.

The benefit of the second method is that there is a wealth of knowledge on programming the PM6 that can be found here, and all or nearly all of the related software is now open source. It would be a monumental effort even if you were an extremely well trained programmer, however. The guys that hang out in the tuning and ECU modification section may also know of a better way, but off the top of my head, there are not a whole lot of options for OBD0, either off the shelf or homebrew, and definitely not on the PM5.