I have a 93 aero 2WD 3.0 with analog dash.
I'm aware that some vehicles have instantaneous MPG gauges. I'm not necessarily trying to get a MPG gauge in my van(although it would be nice), but is there any thing in my van that I can tap into that will at least give me an idea of what my instantaneous fuel consumption rate is?

I like having access to data.
So far I’ve installed a tranny temp gauge. My transmission seems to run around 150 degrees Fahrenheit.
I would also like to install a torque converter lockup indicator light sometime. It’s hard to feel in my van. I'm not sure if it locks up at all. Gas mileage is poor but one thing at a time.

 

This came up recently, but I don't remember seeing any real resolution.

I think you're referring to the MPG displays on the digital instrument cluster. That display doesn't really tell you the fuel consumption rate directly, but you can calculate it with your vehicle speed.

The digital instruments interfaces with the engine control computer, most likely through a set of wires designated as "data link" (pink/light green, pink light blue, and tan/orange). I'm not sure how you would read that data without the cluster.

A more direct way may be to tap into one of the fuel injector wires. You can rig up some kind of magnetic pickup around the wires or the injector itself, and measure the duration of the injector pulses. Take some emperical measurements, and you can probably figure out the fuel delivery rate.

 

I recently went through this exercise when I installed a trip computer (trip minder the official Ford nomenclature) from a digital Eddie Bauer into my XL.
It displays instantaneous mileage and overal mileage readings. As inputs, the following signals are used:
1. Battery power
2. Switched power
3. Display Illumination
4. Button Illumination
5. Fuel level input
6. Display illumination ground
7. Fuel Tank size select input
8. Ground
9. Vehicle speed input
All of the above signals are available in the analog dash wiring. The one signal that is used in the MPG calculation that is not available inside the analog dash version of the 'Star is "Fuel Flow Input". I had to grab this signal from the plug on the EEC (pin 34).

Hope this helps.......

Klaus Cook
Houston, Texas

 

Great Post. . . . It about sums it up!

Not sure the avg layperson knows STAR means Self Test Automatic Readout, or what that function is though. It's the command prompt or CMD function to access D-code & Sys Check sequences in ECM an analyzer, or other remote device can read from.

FBp

 

Excellent info. That definitely gives my a place to start from.
I'll try to learn more about the stuff you just told me about and see what I can do.
Thanks.

 

I think I'm going to have to put this project on hold or forget about it all together.

Instead of tapping into the wire that I know specifically goes to pin 34 on the PCM, I tapped what I think is the same wire only it's on the big square connector below the PCM connector. I think it’s the same wire because my continuity meter says it's the same and it is the same color (light blue/pink). The ford technical service publications CD has a section called "Connector Face/Pinout Charts" it tells what all the PCM pins are but it doesn't say anything about this big square plug at all? I find the ford CD a bit hard to navigate at times. Is the info on this connector not there or did I just fail to locate it? here's a pic of the connector that I can't find info on. The wire I tried to analyze is the little blue one on the very top with the little green arrow pointing to it.

Anyways, with my regular meter I didn't detect much AC or Dc volts. I probed it with my oscilloscope and saw this.


On the left part of the scope screen you can see what appears to be some type of signal. I estimate that it's approximately .1 volts and about 4 kilo hertz. I don't know much about electronics or this circuit in general so I don't see how I can put this little voltage ripple to use.
Edit:I tried reving the engine to see how the signal changes. It seems to produce these litle ripple events more often But I'm not positive.

Edit:I might try xlt4wd90's suggestion sometime and try to use injector pulse width.

 

On my '90 Aerostar, I installed a small vacuum guage. It fit neatly between the two A/C vents over the radio. It didn't tell MPG, but sure helped me to not be lead footed. I would love to have one in my current, '96 van, but I havn't found a good location for it.

 

Aeromac121! Tis pin is on the ECU connector, and it is unused on my van (no wire!). I want to install digital dash with trip computer from Contonental '89. But I cant find diagrams of continental. I'm looking for other ways.