What are the options or methods to work out how the fuel injectors are currently wired or paired if I don’t have a wiring diagram for the custom loom in the car. It is a 305 TPI 1985, currently using an aftermarket ECU that I believe has only 4 injector drivers. Therefore the injectors must be paired (2 per driver) Or it could be currently set up as left and right bank of cylinders with 6 injectors into a driver.COld start is not used.
It is a definitely multi-point batch fire currently, which I want to keep when I swap over to a new ECU as this has only 4 injector drivers.

The 2 pin Bosch injectors are nicely wired at the plug and have an outer protective wiring sleeve right into the main loom, so using wire colour is not and easy option.

Can testing be done at the plugs to look for continuity between 2 or more injectors, or is there another method? I am not confident attempting to isolate and trace from the ECU plug back to each injector plug, although consensus may be that this is the only accurate way 😩

 

Only 1 driver for injectors

 

I understand some setups use a single driver but if you had a car brought in to your shop for a new ECU and had to determine if the existing set up had all injectors on the same driver or paired using 2 -4 drivers, how would you do this.

 

What ecm is going to be used ? Recommended injector number it can control ?
ohm of injectors being used ?

 

On different pages here. It’s a new Haltech Elite 1500 ECU which recommends 4 drivers but my post was asking the question how to test what the existing loom set up is of the injectors and whether they are x1 or x2 or x4 and which cylinders numbers have been wired together. There must be some pairing on the current set up because the existing ECU has only 4 injector outputs, so how to test which injectors are tied together.

 

posted the 85 tpi 1226870 schematic. Isn’t the 1500 for a 4 cylinder engine?

 

Elite 1500 is fine for 8 cylinder semi-sequential
I did mention initially that my car has a custom loom and I can’t be assumed that it is a factory set up, so the 85 wiring schematic you provided is not helpful. That the entire point of the post is how to determine the pairing sequence based on the actual wiring.

 

Yours saying it’s 85 tuned port, but it’s not !
if you know the wire colors at the ecm unplug all current injectors and plug in one injector. Use an ohm meter to find what wires have resistance of the injector to determine how it’s wired. This will take awhile to figure it out . Sounds like you would be better off running dedicated wires over guesswork.

 

The casting number of 14010201 makes it 1982-1985 305 small block. The cast date is A055, which I believe is Jan 5 1985. This would make it a GM LB9 TPI.

I’ll attempt to trace the injectors from the ecu otherwise a new loom is the best option.