AE86 4AGE Engine Extinguishing Circuit

[JenTLy]

Hey,

I am currently installing my alarm which comprises of a turbo timer and keyless start. I have sussed out most the wiring but I cant find the "Engine Extinguishing Circuit" on the 4AGE. I have the wire ready to go but I just dont know where to tap it onto. Im pretty sure that the wire is for the delayed engine cut out for the turbo timer - please correct me if Im wrong

If someone could shed some light or point me in the right direction that would be mostly appreciated.

Thanks,

[clubagreenie]

You would be right in saying it's for the timer shutoff. Where to connect it would depend largely on how the system turns the engine off. The instructions for the alarm should tell you what part of the start/run circuit to connect into. "Engine extinguishing circuit" is pretty vauge. AFM vs MAP may also have a different system.

What you have to establish is what turns the engine off. You need to eliminate spark, air and fuel. You need to shut off the injectors and stop the spark. Something in your system controls this since it already happens when you turn the key off. Probably by removing power from a relay. So no fuel or spark means engine slows and if its AFM, when air flow stops, the flap closes and this triggers the fuel pump relay to open and stop pumping fuel. Also means that if you have an accident and the engine stalls that it won't pump fuel everywhere.

EDIT: After looking at the diagram more, you might be able to put another relay in the EFI Relay power supply line, using the shutoff wire to switch it on/off (again depends on what the wire does (power or earth)) This looks like it would cut power to the injectors and fuel system.

Not sure about what the last stages of a MAP engine are.

On the old site there in the tech section there is a listing for the AE86 book incl wiring as well as many others.

Also sideshow and mos on the forums are the considered wiring gurus.

[JenTLy]

Hey,

Well the instuctions isnt helping much as all it says is "Yellow wire to engine extinguishing/cut off circuit" I'll keep trying to have a look but not too sure what needs to be wired to what. By the way, its a 4AGE MAP sensored.

Thanks for the help anyway clubagreenie

[clubagreenie]

Test if you can what the wire does when activated. This will determine how to connect it into the circuit.

[Mos]

MAP sensored ECUs typically control the fuel pump directly, through a wire (usually FC) that connects the negative end of the Circuit Opening Relay (fuel pump relay) solenoid to ground. The positive end of this relay solenoid is supplied from the EFI relay - this is how the MAP 4AGE is setup.

Flap style AFMs typically control the Circuit opening relay through a switch to ground in the AFM that functions in the same way as above.

Note that interrupting the FC signal is not necessarily the best way of disabling the engine as a correctly wired engine loom should have an Fp pin in the diagnostic connector (or in the diagnostic plugs) that can be jumperred to B+ (Efi relay output) to restore fuel pump operation. If this part of the diagnostics was not wired up, interrupting the FC signal is a suitable option.

Other than that, you have a choice of disconnecting the EFI relay output, the coil/injector supply, distributor sensors, coil drive and feedback signals, etc. There really is a ton of stuff you can interrupt to disable an EFI engine.

It depends exactly what the wire does to determine how safely you can interrupt different signals. If it's just a relay contact you can safely disconnect pretty much anything.

Also note that disconnecting the power supply to the ECU (ie +B/+B1) may not yeild a dead ECU as protection diodes from other signals running to the ECU can leak enough current to power the ECU - this is very ECU dependent.

Your engine extinguishing wire is unlikely to be the turbo-timer support. If you connected anything on the ignition switch, that connected 3 or 4 wires, they're probably for the turbo timer, but they may not be setup in a way to disable the engine.

There's a lot of variables in this unfortunately...

HTH.

Mos.