TOYOCOM:: Universal mode with a carburetor.

A LITTLE BACKGROUND

A year ago I was given a 1990 tercel DX coupe. It had issues to fix and I was glad to know how to.
It was then 28 years old while still showing under 100k km (about 60k miles) on the clock.

It got fixed here and there in the last year span; tires,suspension,brakes,body panels and exhaust system, engine valve seals and timing belt to name a few. The good old trusty 3E grew on me in that time lapse since it was so reliable, overshadowing the fact it is under powered to the extreme.

ENGINE OVERVIEW

It has got 82 hp and an A/T 3 gear transmission. starts like a charm on cold weather

It's an 1.5L 3E engine from 86 to 90. This engine uses a carburetor and a computer to control some peripherals and monitor it's overall operation. Very few existing sensors are useful on it, an oxygen sensor is there at least. all other sensors are switches. no analog sensors at all.(digital throttle position switch and digital temperature and vacuum switches)

The vacuum diagram is as complicated as a wiring diagram for a much more complex engine.it was the time where carburetors had to let got to full EFI.

Only E1(ground) and the VF (fuel trim) were available in the diagnosis box for the TOYOCOM to use. not even switched power (+B). Improvements had to be made to take full advantage of this setup.

GETTING  SOMETHING INTERESTING INTO TOYOBD1

An android car radio was installed to be able to gather data all the time from the TOYOCOM unit installed in the engine bay (blue box in the upper right corner of the preceding picture). this radio is setup to connect to the TOYOCOM every time TOYOBD1 starts.

• VF is already there
• E1 is already there
• +B was routed from the engine harness reaching the fuse box.
• Ox(oxygen sensor)  was routed into AB
• Moving speed is taken from the android car radio GPS

Even though there were still custom inputs available on the TOYOCOM nothing else was routed to the diagnosis box yet.

WHAT WAS LEARNED FROM TOYOBD1

• the alternator is poorly working but still operational. (battery voltage is low under all conditions)
• the engine runs rich while idling and lean when held at WOT for a long time in 2nd or 3rd gear. it might have fuel delivery or carburetor issues
• the fuel trim is always negative ,meaning the ECU suspects the fuel consumption is less than expected. It might be the oxygen sensor, might be fueling issues again. 
• throttle position and temperature switches are working OK, the system goes from closed to open loop following engine load and growing engine temperature.

WHAT IS COMING AHEAD

More custom sensors are to be mounted on the engine to even out MPG calculations reserved only at this time to EFI engines. more sensors will be added to monitor the engine tune and improve it along the way as possible.

• fuel flow sensors on fuel lines
• MPG calculations for a carbureted engine in TOYOBD1
• dirt cheap wideband oxygen sensor setup
• rpm input from the igniter

TOYOCOM :: Universal mode on the AW11 blue top 4A-GE

WHAT'S THE BIG IDEA

Having modern day diagnostic features on an car is very useful. On a +30 years old car it is a luxury that is rarely found. For Toyotas there is hope now. Using the toyocom 'universal mode' you can get a fair level of information out of our  mid 80s toyotas.

Doing so requires of the car owner to do some electrical work to splice into signal wires we care for. A compromise was made to leave the wiring harness untouched. It may be more ambitious but certainly not out of the reach of the DIYers.  What requires to be done is to solder wires on the underside of the ECU main board, exactly where the ECU connector are soldered. This location gives us acces to every wires going into the ECU and is conveniently labeled on most toyota ECUs.

RANDOMNESS STRIKES

Believe it or not, while working on this blog post a friend passed by with a beaten up mr2 while being in transit to somewhere else. It was shear luck,so we took the time and tried the modified ECU on it!
The car was in really bad shape but running,no exhaust with the blue top 4A-GE not running on all cylinders. we were able to get our readings while being quick at it to not wake up the city neighbors.

WHAT YOU CAN EXPECT IN THE ANDROID APP

mandatory features from universal mode on an early EFI toyota.

• Error codes readout
• battery voltage
• fuel trim

mandatory wires you have to solder

• B+ 12v power
• E1 ground
• T (TE1) trigger error code output
• W check engine light
• VF (VF1)  fuel trim

additional wires you should monitor before anything else

• IGT this is the igniter control (for RPM input)
• #10 this is the first injector pair control
• VS  this is the air flow meter output
• OX this is the oxygen sensor
• THW this is the coolant temp sensor

reasoning

• having RPM & injector activity allows us to get injector duty cycle
• having the air flow reading tells us about the engine load which is always useful.
• having the oxygen sensors allows us to troubleshoot fueling issues against engine load & rpm
• having coolant temperature allows us to know if we overheat and guess the fueling choices.

WHAT YOU NEED TO GATHER

• a toyocom scan tool from www.zf-scantools.com
• a spare ecu for your engine is best.
• a junk yard diagnosis box, preferably a late black one from an obd2 toyota.
• new contact pins from digikey (only usable with the late black diagnosis box)
• 10 wires of different colours. about 1' long 20ga

WHAT REQUIRES TO BE DONE ON THE ECU

To understand how to install contact pins in the diagnosis box follow this earlier post.

where each wire goes in the diagnosis box

ORANGE                =         +B
RED                        =         VF1
DARK GREEN        =         E1
NORMAL GREEN  =         AB
YELLOW                =         W
WHITE                    =        TE1
BROWN                  =         TT
BLACK                   =        TS
BLUE                      =        TC
PURPLE                 =        VF2

• install contact pins on each new wires you need  ( a feet long is comfortable to work with)
• place the wires in the diagnosis box at the specified spaces in the top cover

• Add a shrink wrap sleeve to your new bundle of wires
• Remove both top and bottom ECU cover plates
• on the TOP side,read the labels for the connector pins to know where your signals are located.

YOU WILL BE SOLDERING ON THIS SIDE

where each wire goes on the ecu connector

ORANGE goes to +B
RED goes to VF
DARK GREEN goes to E1
NORMAL GREEN goes to VS
YELLOW goes to W
WHITE goes to T
BROWN goes to THW
BLACK goes to #10
BLUE goes to OX
PURPLE goes to IGT

Overview of the work done ot the ECU

PLEASE EXCUSE THE HASTY SOLDERING

• solder each wire to it's matching pin
• reinstall the top cover plate.

• Applying hot glue with a glue gun over your work is suggested for shielding and dampen vibrations.

before installing the bottom plate you want to add washers to shim the cover and use longer bolts to compensate, doing this drops the chances of the wires cutting themselves due to friction.secure the added wires to the ECU case using hot glue, to lock them in place.

• connect your ECU to the car and the toyocom into the diagnosis box.
• at this point follow the toyocom user manual given with the tool to start using it.

TOYOCOM :: playing with contact pins in the DIAGNOSIS box

With the TOYOCOM & TOYOFAN tools it is now possible to do more than before with the OBD1READ. This takes advantage of what the DIAGNOSIS box offers by default and allows the user to expand the inputs using empty spaces when availalbe.

Sometimes, depending on engines and wiring harness variants some mandatory wires have been omitted from the wiring harness and require to be added so the TOYOCOM tool can be used at it's fullest. This can be accomplished with simple tools without removing the wiring harness from the car.

Getting contact pins, 2 ways to do it

1. cut off a spare diagnosis box at the junkyard and reuse it's contact pins.
2. use brand new contacts that you will crimp and solder to new wires.

IF YOU HAVE A GREY DIAGNOSIS BOX YOU CAN ONLY REUSE CONTACT PINS AS OF YET.

I will only describe how to work with new contact pins in this post, the theory on how to pull contact pins from a diagnosis box is described in the later steps. 

You can buy suitable contact pins online from Digikey. A123029CT-ND on digikey

The tools and parts I used.

Getting the contact pin on the wire

Soldering is used to compensate for the loose the crimp tool may leave. 

Getting the new contact pin into the diagnosis box

Hold the diagnosis box so you can read 'DIAGNOSIS' (not upside down.)

 Be careful so the contact pin 'wings' are facing up

You will hear this sound when the contact pin locks right.

Pulling out contact pins from the diagnosis box (applies to BLACK and GREY boxes)

Position the diagnosis box facing you and so the cover sits at your right

 Using the precision flat screw driver you will pry the lock teeth toward you.

 While you are holding the lock teeth with the screw driver you will use another hand to pull the wire from beneath until it is totally out of the box.

Closing the clam shell in the end.

TOYOCOM :: Adding custom pressure sensors

Adding custom pressure sensors for use with a TOYOCOM device

Today I will show you how to add a third party oil/fuel pressure sensor to an ST205 3S-GTE wiring harness. this sensor is only going to be useful if used with a TOYOCOM device & TOYOBD1 android app. No other system care for it's reading and it cannot affect the engine performance adversely.

ST205 bench harness used for the demonstration

The 0-100 psi oil/fuel pressure sensor we will be using

This sensor is found easily on E-BAY for about 20 CAD each, comes with it's pig tail and can be ordered for various pressure ranges. In the case of most Toyota engines, an oil pressure reading of 0-100 psi seems adequate. Similarly fuel pressure on those engines are not meant to reach 100 psi so this range is fine for both uses.

The pin out if this sensor is very simple. (if in doubt with a particular model ask me)

1. BLACK = sensor ground (goes to Toyota wiring E2)
2. RED = sensor reference voltage(goes to Toyota wiring VC)
3. GREEN =  output signal , this goes straight to the TOYOCOM device only.

 

The ST205 ECU wiring diagram with today's additions

Show below is the test bench incarnation, only aligator clips wires have been used. In real life solder and isolate your wires The new green wire has been routed in an empty spot of the diagnosis box , into VF2, the matching VF2 pin of the TOYOCOM device can read 0-5v analog signals or frequencies. Red and black wires have been tied to TPS wires due to the ease of locating them, depending on your specific cases those same wires could be had near a MAP sensor also. please ask if in doubt.

 

 

 

 

 

 

 

  

 

You can now plug in your TOYOCOM device and power the whole system

 Now the Software configuration

In the TOYOBD1 app you will need to have already paired and connect to your TOYOCOM device, you will also need to have set the display configuration to see the VF2 input.Then we will be able to apply the sensor curve to this input and get what we want.

Sensor curve for use in TOYOBD1

The curve for use with this sensor is available on dropbox HERE

 Now click/zoom into the VF2 signal cell, it will not have a sensor curve applied yet.

Then press on the 'ADC' button to prompt the sensor curve selector dialog, there are a few key built in sensor curves but the oil/fuel pressure curve is not built in yet and requires to be read from a file.

 Now press on the '...' button to search for a sensor curves, I placed the file into my TOYOBD1 directory, press OK, then back into the sensor curve selector press apply sensor curve.

 At that time the VF2 cell will have changed, it will not show the measurement unit from the selected curve, if you don't have a gauge but text display and wishes the gauge, just swipe left/right on it , it will come.

Whole screen after clicking/zooming out of the VF2 cell. at this point you are ready to see useful oil/fuel pressure next time you go for a drive.

3VZ-FE ECU modification : disabling A/T logic

Most 3VZ-FE ecu found are A/T variants. 

Due to the scarcity of M/T ECUs tricks have been developed to keep an A/T ECU from throwing error codes while using it on an M/T car. those strategies have been performed in the wiring loom but it can be performed surgically from the inside which feels to me more desirable.

A/T logic can be shutdown from inside with a handful of steps

Thanks to Toyota for their 80s and 90s ECU design, for splitting key tasks across multiple processors. Namely Engine management, transmission management and knock control. this allows us to take away part of it's logic at it's root while not affecting other processors work. 

Circled in red are locations where work need to be carried out.

tools required

• the ECU already pulled out of the car, so all tools you can think off for this
• screw drivers
• cutters
• Soldering iron under 100 watts
• tweezer to hold surface mount resistors

Steps

1. remove A/T processor quartz X752
2. change engine processor resistors arrangement to match known M/T arrangement R752 goes into R751, failure to do so might bring and engine error 16

1. X752 needs to be cut off from the board using cutters

X752 needs to be cut off from the board using cutters

2. R752 needs to go in place of R751

R752 needs to go in place of R751

Step 2 is the most challenging ,you need to get a surface mount resistor free and solder it on another location. if you don't already feel confident doing so please don't screw your ECU for the learning. find someone who can do it if in doubt.

Results

• transforms a near worthless A/T ecu into a desirable M/T unit.
• no more need to fool the ECU into neutral or simulate shift solenoids
• no more A/T error codes displayed when pulling engine error codes

TOYOCOM : pre-production teaser

 TOYOCOM & OBD1FAN

A replacement for the OBD1READ is brewing since a fairly long time and is now into beta testing.
The new device is meant to replace the earlier OBD1READ 22p and bare. it allows to get the same toyota obd1 data stream and more. offered with the plug and play connector only, it aims to use  every wire available in the cable.depending on the particular car, those diagnosis box contacts may already be populated by other systems, in which case I suggest thinking carefully if you want to modify the diagnosis box pinout or grow one exclusively for usage of TOYOCOM.

only connections present in the plug and play cable.

 
Externally the new tool remains nearly the same ,retaining it's blue clear case. a yellow led was added to let the user know when the obd1 data stream sent by the ECU is received correctly by the tool. This feature allows for better troubleshooting.

TOYOCOM & OBD1FAN  devices are compatible with the already existing TOYOBD1 application and basic usage is similar to the OBD1READ. TOYOBD1 on google play 

the OBD1FAN variant which additionally allows radiator fan control .

Pre-production TOYOCOM Features

• Ligth up a yellow led when the obd1 data stream is active and properly received by the tool.
• activate/deactivate the obd1 data stream from the android application
• read the obd1 data stream when active , sending each field directly. this improvement over the OBD1READ allows to see the data on the screen when it is fresh instead of 1.3s later.
• activate/deactivate ECU error code output
• read the ECU error codes and display them in the android app with a textual meaning
• lock ignition timing when conditions are met, allowing to adjust base ignition timing if applicable
• read battery voltage 10 times per second
• read 1x 0-20v analog signal 10 times per second
• *read up to 2x  0-1000hz frequency signals 5 times per second
• *read up to 4x 0-5v analog signals 10 times per second

0-5v analog inputs into TOYOCOM

0-5V analog inputs suggestion

• THA or PIM sensor, or all other missing from the obd1 stream
• Wideband AEM gauge output signal
• custom added sensors, oil pressure, fuel pressure, additional temp sensors,exhaust back pressure sensors,etc

0-1000hz frequency inputs into TOYOCOM

frequency inputs suggestion

• IGF signal, gives RPM and ignition coil dwell time
• SPD signal, gives differential rotation speed
• one injector negative wire, gives injector PW duration
• VVT solenoid one equipped engine. tells us VVT usage
• monitoring IGF,SPD and injectors allows to calculate fuel MPG in the android app

0-20v analog inputs into TOYOCOM

0-20V analog inputs suggestion

• TT signal when available from the A/T ECU ,tells the selected gear
• dashboard water temp sensor
• dashboard oil pressure sender unit
• dashboard fuel level sender unit

 *some inputs can do both frequency or analog inputs depending on configuration in the android application

 

Pre-production OBD1FAN Features 

• everything TOYOCOM does
• control radiator fan relays according to readings either from the obd1 stream or direct sensor readings
• warn the user of an overheating or malfunctionning fan condition through dashboard light bulb

 

preliminary OBD1FAN wiring diagram

 

New use cases handled by the new tool 

• Allows to directly read sensors we could not get information from in the obd1 data stream.
• Allows to directly read sensors that you added, oil pressure, fuel pressure, etc
• Allows to use on earlier toyota EFI cars with direct readings. giving partial support into TOYOBD1
• Read ECU error codes. 

OBD1FAN fan control features

• Allow to specify the Fans activation and deactivation temperatures
• Allow to control fan activity from obd1 data stream or direct sensor readings for earlier cars
• Allow to engage fans in a preemptive mode meant for traffic jam and track usage.
• Allow to disengage fans below a set voltage,( helpful in winter cold starts or alternator failure) 
• Allow to warn the driver of an overheating condition past a set temperature