hi imp. injectors and low imp. injectors... problem inside

[Toy_T-18]

hey guys, im thinking there may be someone on this site that is going to be able to give me an answer, cause i cant find anyone elsewere

ok so i have my 88 st165 ecu and ive got my car 88 st162, now from looking at whats going on with diagrams and stuff i found out that the gt4 ecu comtrolls low imp injectors that run at about 1.9 ohms, and my car now runs hi imp at about 13.0 ohms, i also have 550cc injectors that are hi imp from an rx7 that run at 13. ohms, now is it possible for hi imp injectors to run on a gt4 ecu without using the resistor pack that is in situe with the gt4 ecu? does this resistor pack make it look like the standar injectors are hi imp, or do they have a make the voltage drop that goes to the injectors,
so quite clearly what im trying to say can hi imp injectors run on an ecu that was designed for low imp???

Cheers Sean

[oldcorollas]

it is possible, but you would want to get the impedance/resistanc as close to the ECU's injectors as possible, or a little higher.
lower, and they might draw too much current.

maybe

[Toy_T-18]

so is the resister pack there to make the ecu look like its seeing bigger imp injectors? so to speek

[MWP]

Yes... thats exactly what its there for.
ECU would have been designed with high impedance injectors in mind, but for whatever reason, they used low impedance on the engine.
So they used a resistor pack to make em work safely.

So youve got a piggyback/interceptor ecu youll be using with the factory ecu?

[auto351]

so quite clearly what I'm trying to say can hi I'mp injectors run on an ecu that was designed for low I'mp???

Cheers Sean

This depends on weather the low Imp ECU is operating in saturation or peak/hold modes.

If the ECU operates in saturation mode (voltage mode ) then a resistor pack will already fitted to the system, this lIimits the current with the lo Imp injectors (1.9ohms) fitted.
by adding your hi I'mp injectors (13.0ohms) you have increased the the total resistance and reduced the total current flow, which now maybe insufficient to run your hi Imp correctly,

When the ECU operates in peak/hold mode (current mode) you need the current draw of the lo Imp injectors.
If the current is the same or similar (for both injectors) then they can go in without a resistor,
If the current is lower for the lo Imp, they will not work correctly with the hi imp
If the current is higher for the lo Imp, a resistor may be needed. this will depend on the difference in current.

Manuel

[MWP]

The ECU is built for high impedance injectors, so the above doesnt apply here.

[Grega]

correct - the driver circuit is expecting to see high impedance injectors. if you run low you will burn out the ECU due to the impedance being wrong.

best best would be to plug in the resistor pack and injector and measure the impedance and see what the value is.

[MWP]

Ahh, but there is the problem... you measure resistance, not impedance.
They are different things.

Odds are the high impedance injectors directly wired to the ECU with no resistor pack will be fine though.

[timbosaurus]

You'll find that different imp injectors do have different resistances too though.

approximately:
< 5ohm is low imp
> 10ohm is high imp