Computers - Syncro T3

The T3 Syncro ceased propagating over 30 years ago. It was created during the age of nascent computerisation in a motoring world dominated by wire, hose and cable connectivity. Its metallurgic bones (wheels, gearboxes, ICE motors, etc) are not that dissimilar to the modern versions, but the way these bones ‘talk’ to each other had changed as computerisation took hold. High powered multi functional computers, modules, Bluetooth, sensors, etc seem to operate on telepathic waves to keep a vehicle viable. Efficiency, yes. Reliability, problematic. Durability, debatable. Technology, definitely.

However the T3 Syncro (30 years plus) does have a dollop of computerisation at its heart - ECU. This rudimentary device caused me great annoyance a few years ago in the NorthernTerritory. It is responsible for the happiness of 6 operational parameters under its wing. Each parameter went independently and intermittently awry and and as I tackled each one as they malfunctioned, I found no obvious fault with each component. My folly was that I was from the world of wires, hoses and cables and as such I followed and focussed upon these pathways. Meanwhile unbeknown to me the ECU was having palpitations and fibrillating. I raised the rear bench seat to check the auxiliary battery (clutching at straws here) when I noticed the ECU. Hang on, I thought; ‘you control all those things’ causing me grief. Fortunately I carried a spare and swapped it - nirvana!

I then understood why modern vehicles have computer diagnostic units to trace faults. I can live with the simple Syncro ECU that may need a transplant once in a while.

Yes I have a spare ECU for my 2wd.

I even keep a spare ECU for my syncro’s EJ25 donk even though it has OBD2 which I can read with the appropriate device.

I have to say- the OBD2 is brilliant and provides lots of information and you can even set up real-time gauges on your phone or a screen to advise how it is behaving.

diagnostics for your T3 :slight_smile:

I should have added, don’t forget the idle control module (behind the right hand tail light) which can also have failures.

All good Richard, I bought the shoebox shortly after that ECU incident and, of course haven’t had to use it since. But the ECU is on notice now that I have it, haha.

I wasn’t aware of this module. Does anyone know if it has any affect once converted to EJ25? I’m having idling/stalling issues

The Ej25 has its own IAC unit which is bolted into the throttle body and controlled by the Subaru ECU (assuming thats how your conversion was done).

I had issues with idling with mine and took mine back to Andrew of AGT Engineering and he sorted out the issues by earthing a couple of pins.

I also replaced by throttle body as I had trouble getting a good new IAC valve yet I think my problem was the way the computer was set up trying to look for the former Subaru auto transmission that is was previously couple to.

Works brilliantly now.

I note you must also have a speed sensor if you want the engine to idle properly.

As Scott noted, the idle control from the T3 has nothing to do with the Subaru.

I have not used my shoebox kit yet either. It does require a functioning ECU to work and would not detect errors in the idle control system. It merely picks up the inputs going into the ECU and signals going out to the injectors. Not as sophisticated as modern systems, but we also have a much simpler system to diagnose!

The ECU’s can be used as a core to exchange for a re-built one. Freight costs make this and expensive turn around though.

No problem Richard.
My reply was actually to Syncroed’s comment just above mine as he seems to have idling issues with his EJ25 conversion.
They can be hard to get right as they reply on a number of factors/ inputs unlike the VW version which has that control box behind the drivers side taillight and the phallic vibrating nugget IAC unit on top of the engine plus the ECU to control idle.
Probably a simpler system.

Thanks, yes just wanted to make sure as this idling issue has appeared after a dead short and subsequent repair. The ECU required repair but, after exhausting every other possible component, I’m starting to think the repaired ECU is not quite right.

Just out of interest, are these EJ25 ECUs easy to get hold of? Reading the above I feel carrying a spare wouldn’t be a bad idea… Also are they different for an EJ25A, EJ25B etc?

I would say you could get one for your model without too much trouble, yet apparently you need to “Flash” them in to get them to work.

I had a subie guru from Neville in country NSW (near Bathurst) do mine at with his equipment it took him less that 30 seconds to flash a different ECU in.

Its the immobiliser that is the problem as they are matched in with the immobiliser module.