Can S80 12v+ be less than 40amps?

Wiring best practices and loom building technique
MarcoV6T
Posts: 101
Joined: Tue Jul 26, 2011 12:20 pm
ECU Model: S80 Pro
Firmware Version: 58

Re: Can S80 12v+ be less than 40amps?

Post by MarcoV6T »

Just to add some info, when using amplified coils(and thus amplified coils enabled in the software), the DTA ECU will draw >3A when the engine is not running, due to the inverted coil output's(which heats-up the ECU case).

So a 5A fuse should do for the ECU, and should blow(inverted diode over the supply) without frying the PCB in case one reverse wires the ECU supply.

Regarding the debate above, the ground is evenly if not more important as the positive supply, to and from the actuators and sensors. If you take a good look to automotive wiring, then you'll see that most of the wiring starts/ends in a star configuration(drivetrain related).

Start from one point for the supply, and end at one point for the grounds(if physically possible).

In my car I've one big wire from the battery that goes to a fuse/relay box, which feeds the ECU, fuel pump, coils and injectors. The coils and injectors are fed from one relay/fuse combination, the fuel pump(s) from another, and the ECU again from another fuse(5A)/relay combination.

The ECU relay is switched on from the ignition key, the coils/injector and fuel pump relays, well from the fuel pump ECU output.

For the TO, if running amplified coils, you'll need that configuration above(coil supply only when the fuel pump is running), because as already mentioned in other topic's, you'll have(almost certain) coils firing when switching the ignition key on.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Can S80 12v+ be less than 40amps?

Post by stevieturbo »

The amplified coils would fire on mine as you describe, but unless I'd being doing silly things like lots of start/stop the engine, it never shown any issues.

If I had been doing that, then you could hear it attempt to fire on key on as it ignited some of the fuel that was lying.
MarcoV6T
Posts: 101
Joined: Tue Jul 26, 2011 12:20 pm
ECU Model: S80 Pro
Firmware Version: 58

Re: Can S80 12v+ be less than 40amps?

Post by MarcoV6T »

Well a leaky injector or bad injector output driver can do nasty things in combination with a unwanted spark...

Or, say you have wrong numbers in the start-up(cold) map, and you flood the engine or it just doesn't start but there's fuel left in the cylinders, and like in many cars you have to 're-arm' the ignition key, then you have your scenario for disaster.

If you cut corners, then sooner or later something will happen, it's just a matter of time.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Can S80 12v+ be less than 40amps?

Post by stevieturbo »

The firing isnt unique to DTA, I've seen guys mention it on Motec and haltec forums, and my Syvecs does it too.

If you're flooding the cylinders, really you have far bigger issues to worry about.

In the 7-8 years I've ran these coils, it has never been anything I'd consider a problem or be remotely concerned about

If the ecu is tuned badly...again that is the problem you need resolved. But yes there is no harm wiring it as you suggest, but for me and anything I've ever worked on, it is a non-issue.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Can S80 12v+ be less than 40amps?

Post by stevieturbo »

Just for an update.

Relevant or not..

I tested my injectors today, I run 2 x 660 Siemens in parallel. ie they fire together. One is a tall, the other shorties.

2 injectors fully powered on draw 1.7A, so that's about 0.85A each
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