Anything not specifically related to the Speeduino hardware. Eg sensors, bluetooth, displays etc
By Leighowar
Hey everyone I'm completely new here and new to speeduino to, I own a 1977 ford Capri with a BOA cosworth engine in it currently running EECIV factory management, however within the next few weeks this is going to be replaced with Speeduino Core 4 ECU from DIY EFI,

So.. I'm trying to achieve something that I'm not sure is possible, the trip/fuel computer out of the original car *ford Granada Scorpio* I would still like to use with my Speeduino

Some people say it's possible some say it's not.

The only signal which hurts my brain is on the EECIV ECU pin 34 goes direct to the trip computer and I'm assuming because I can't find any technical data that this pin 34 calculates injector timing to be able to display a MPG calculation on the trip computer screen

All I wanna know really is , Is there a way for me to use this old trip computer with my Speeduino and get it to display the mpg like the previous ecu
User avatar
Your question cannot be answered until you know what signal is going to the trip computer. The signal type, data and format. With that info, most things are possible.

While many here use the mileage, power, acceleration and many other outputs in TunerStudio (and some other prog's), at worst-case your trip computer should be usable with an intermediate "translator". Easy is an Arduino type, listening to selected Speeduino data via serial3, CAN, etc, and passing the data to your trip computer using the info provided above. This avoids modding the Speeduino code for a special function and simplifies the process to get what you're after quicker.
User avatar
By dzener
Hi, I don't know how your Ford works, but if it's like my 2005 Corolla (1zz fe) that has a pulse wire from injector 1 that goes to the on-board computer (analog system), then if you keep the original injectors without changing fuel pressure, adjust dead time, it should work like original.
Connect an oscilloscope to this signal wire to see what information it sends.
By Leighowar
Thanks for the replies guys, so I've since done some digging and I'll list what I've found

Apologies for it being very big and in-depth , it means nothing to me but might to you guys.

Pin 34: Data Output Link

The Data Output Link (DOL) provides a communication line between the EEC and
the vehicle dashboard computer, Tripminder, for the transfer of fuel
The Tripminder requires an appropriate integer number of pulses within 100
msec period. Therefore, within each background loop or each 100 msec period,
whichever is shorter, the EEC sums the fuel flow and through the injectors
output since the summing period started, converts this sum into DOL pulses,
and outputs these pulses at a maximum frequency of 500 Hz during the
following summation period.
The fuel flow is converted into DOL pulses according to the following
The FUEL_SUM is then reduced by the amount converted into DOL_COUNTS (One
DOL_COUNT = 1.282E-4 lbm).
DOL_COUNT = Number of pulses to be output beginning
in the next summation period. One
DOL_COUNT = 1.282E-4 lbm.
FUEL_SUM = Sum of fuel flow per injector, which was
initiated since last summation period. It is
updated during the Fuel PW output routine.
7804.19 = (48000 pulses/gal)/6.15 lbm/gal, pulses/lmb.
INJOUT = Number of injectors per output port.
(See Fuel Strategy)
LBMF_INJn = Fuel Flow per injector, calculated from
FUELFLOWn (n= 1, 2). (See Fuel Strategy).
---- ---- ---- ---- ---- ----
| | | | | | | | | | | |
| | | | | | | | | | | |
FUELPW ----- ----- ----- ----- ----- ------
|<-- 1 BACKGROUND LOOP -->|----
|| |
|| |
DOL | |

If you use an EECIV, the box code calibrates the Pin 34 out put to suit the injection type, injector type in pounds per hour, and if you mess with it, you then sclae you
r mpg up or down, because the Pin 34 out put is just the nuber of activated pulse widths based on the factory injector for the engine. For example.
Fuel flow based on 19lbs.

So... The EEC iv collects information from injectors and vss, also from fuel remaining in the tank from the ohms on the tank sender

This is then translated and sent down pin 34 to the trip computer

Pin 34 of the ECU essentially just emulates carburettor fuel flow sensor,

For the trip computer to work it needs a square pulse wave signal a High of 9 volts or above and a low below 4 volts for fuel input.

The trip computer needs a VSS input of 8000 pulses per mile

Fuel input is calibrated at 48000 pulses per gallon

The distance input is AC and must swing at least 0.3 volts above and below ground. This is meant to be hooked directly to the magnetic VSS sensor
User avatar
OK, so you are still missing some info on what data is used in what way in some steps in that post. However, it is clear the Pin34 signal is a calculated value rather than a simple pulse train type-of-thing. I would say that your success on using this specifically-calibrated unit would rest on your ability to create clear math for calculations.

In other words, what data from Speeduino (and other specific sources), used with what clear math, gives the result that is then formatted to the DOL spec? Post an algorithm that demonstrates the use of specific data to reach the result. It is outlined in your post, but now needs the missing info and an example. The code may be written from there for handling the data, running the algorithm, and formatting the output.

So, I'll give you a third answer. Yes, it can be done. No, it won't be as easy as creating a fresh data display design, as it must comply with existing trip computer requirements for almost everything. This leaves you with a decision of whether to pursue this path, or choose another to get the results you require. That is your judgment, and a balance of everything from plug 'n play, to hours involved, to perfect originality, and many others. There will not be many requiring this function, so consider you are doing this mostly on your own (one of the decision factors). Good luck!
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