TOYOCOM :: the one wire interface

 Allows to compute fuel consumption ,trip information and basic injector usage out of one added wire on nearly all early EFI toyotas, without the obd1 data stream.

benefits

• extremely easy one wire job, fast and simple.
• allows to get many information out of it
• -injector opening
• -engine rpm
• -injector duty cycle
• -fuel consumption
• -fill the built in trip computer
• faster refresh rate than regular obd1 mode

pitfalls

• loses RPM when injection stops, happens when deceleration fuel cut off occurs

*All pictures in this post have been highlighted in blue to improve understanding

TEST MULE

1997 1mz-fe V6 in an MR2  , without relying on obd2 or obd1, using only the Toyocom universal mode

PHYSICAL WORK ON THE CAR

• you need to have a toyocom as found on www.zf-scantools.com
• you need a diagnosis box with at least +B and E1 (grey and black diag boxes have it, obd2 cars might lack some pins)

1MZ-FE DIAGNOSIS box with added VF2 contact pin

install a new wire from VF2 in the diagnosis box to one injector wire of cylinder 1 (#1 or #10 on the wiring diagram of your engine. for this particular installation the last cylinder of the front bank was chosen due to the ease of reach.

A T-junction was made at the #6 wire where it was easy to reach

the same zone seen from a far before the new wire was tucked in

follow this link to understand how to open up the diagnosis box and add a new metal contact in there for your new wire

ANDROID APP SETUP

following this video you should be able to mimick the setup for your own car. resumed below are the steps.

• go to main menu
• go to display settings
• show GPS
• show VF2
• show VF2-2
• remove obd1 specific fields
• go back to main menu
• go back to main display
• click on VF2 cell
• apply injector opening sensor curve on VF2 (leave MS as the measurement unit)
• apply injector opening sensor curve on VF2-2 (swipe up on the cell to reach either RPM4,RPM6,RPM8)
• go to main menu
• go to device features
• set the tool to UNIVERSAL MODE
• set VF2 as frequency input
• set rpm channel to VF2-2
• set injector channel to VF2
• set speed channel to GPS
• press apply device config
• go back to main menu
• go back to main display
• you can additionally remove VF2,VF2-2 if you wish to clean the display, this won`t break your setup.

THEORY OF OPERATION

Free from the phone itself we get GPS moving speed.
By monitoring an injector wire we can get 2 different readings

• injector opening duration
• engine rpm

with those 3 key readings are computed injector duty cycle, fuel consumption,MPG and the trip computer data.