Circuit Open Relay(COR) Part number 85910-12080 question

[Futo_gt86]

Sorry, read Edit
Never done MAF/COR before.
LS400 used funky fuel pump controller set up, massive (and expensive) heat sink looking gizmo which I don't fully understand or have, so went for COR.
Just asking the question as the last bit got me jumping.
But in saying that, If I stay clear of FC pin on this ECU (half speed pump) and use FPR to trigger COR it should work?
The write up states FPR won't trigger "normal" relay, hence why I was looking at MAF directly.
Is COR lower voltage the "normal" relay?

[Golberg]

I understand better now, I didn't realise it was a 1UZ you were wiring.

The information on that website is unclear and I'm almost 100% sure its wrong.

So you've got your FC and FPR pins. (This is how Toyota normally does fuel pump wiring with those pins)

FC triggers the COR its a ground trigger (unlike the dopes on that website seem to think, I don't know why they'd think it would be a + trigger, basically nothing on an ECU is. That's why they are seeing 0.004 volts, thats 0v = negative)

When FC is triggered it allows power to get to the fuel pump through a resistor (for low fuel consumption states, idle etc)

FPR triggers a separate relay (negative trigger again surprise surprise) that bypasses the resistor and gives full fuel pressure.

If you want to avoid using multiple speeds on the fuel pump just use the FC trigger and ignore the FPR

[Golberg]

Don't try to trigger a fuel pump off the AFM, its not designed for it and you'll stuff it.

[Golberg]

I've simplified a random Toyota diagram for an ECU that has FC and FPR pins on it so you can see how they'd usually be wired:



I can't say for sure that this is correct for the 1UZ ECU, but I see no reason why Toyota would do it differently for one car when this is how they usually do it.

[Futo_gt86]

OK, I'm listening, and referencing to other info that I have come across.
I originally intended to use FC , as on previous MAP engines this is what I have done, and the ECU pin out diagram I have for this LS400 ECU says FC = COR


But, why then does Hen state on Toymods to use FC pin for MAP, or direct to AFM for MAF

Quote
"The running coil is triggered differently on AFM and MAP engines. For AFM there is a contact in the air flow meter which closes as soon as the flap opens at all (meaning the engine is sucking air, so must be running). For MAP there is a pin (usually FC) on the ECU which is earthed whenever the engine is running."

And
"If you aren't sure which pins on the AFM to connect to then they are easy to find with a multimeter. Just find two which are an open circuit when the flap is closed and then go to zero ohm as soon as the flap is opened. They also tend to be the two pins at one end of the connector."

With this diagram?

[Futo_gt86]

So you can see here how I reached my question of which wire to use a MAF connector.
I'll use FC, as this makes the most sense to me.
Hen feel free to chime in on this...

[Futo_gt86]

So, hang on, in reference to BOLD font above, what about MREL for main EFI fuse, I followed this guide to wire the entire vehicle, in which it states
Pin Number 24 MREL - EFI Relay (turn on)
... (NOT A Core Wire) – MREL EFI Relay (turn on) - this wire comes from an ECU PIN and it goes ro (12+) the EFI replay to turn it on,
... e.g. the relay that provides power to the injectors (only) - turns off when engine not running, I always use this for safety reasons.

If MREL is Neg trigger, then this is incorrect... Or is this one of the exclusion to your reference of "Basically nothing on ECU is" 12V+

[Golberg]

The FC wire shouldn't run to the AFM at all. FC is triggered by the computer when it detects rotation on the crank angle sensor.

SOME cars have a switch in the AFM for a fuel pump but if you've got an FC pin, then use that on its own to trigger the COR.

If your AFM wiring is the same as that diagram on the other page, then there is definitely nothing to trigger a fuel pump in it.

I will concede, MREL is usually a 12v+ trigger, so that is correct.

As a side note, the reason for previous statement:
ECU's primarily use NPN transistors, NPN transistors switch 0V signals. From a vehicle circuitry perspective it makes far more sense to switch as many things with 0V as possible. It decreases the amount of 12V running through wires everywhere which lessens the chances of a short occuring. But it also suits big fuse/relay box layouts better. It also decreases the overall wiring required because 0V can be picked up anywhere on the metal body not requiring an additional wire just to supply a switch.

[Golberg]

Ah I think I understand where the confusion lies now, I just read through that Toymods document.

I think what it really should say is if your engine is MAP then use the FC pin. If your car is AFM then use the AFM to switch the fuel pump if there is no FC pin.

[Futo_gt86]

OK, awesome.
Thanks heaps for all your help here Golberg! and the extra info, makes a lot of sense.
Have COR wired to FC pin, and MREL connected to 86 pin on Relay, 87 to injectors.
I'm pretty close now, got stuff in the way over weekend, but there is slightest chance I might have this thing actually running late sunday avro/night. I'll post up vids when and if.

Tell you one thing, the neighbors are going to know about it with no exhaust!