EFI Wiring question

[justi]

Hi

I have a rover v8 going into an old tvr. It is a lucas efi system. There are the usual four wires - brown, white, whitered and whitepurple - there is also a greyand orange wire - anybody got any idea what it is for?

Also when I run the engine it revs up an i cannot get the idle down - checked for air leaks and I htink I have it sorted - all suggestions welcome.

TIA

Justin

[ramon alban]

Hello Justin, I cant see a Slate/Orange wire in the system so you need to trace its source component or connector.

Find the cct here

http://www.vintagemodelairplane.com/pag ... uit01.html

your high idle problem is called "idle speed hangup" and the problem is addressed here:

http://www.vintagemodelairplane.com/pag ... ing01.html

You have to transpose the solutions to a single plenum system

[justi]

Hi

Thanks for that. I have traced the wire and it is tee'd into the loom with the injector wire coming from an injector and going to pin 14 on the ecu?

It is a loom from a twin plenum. When I took it out the wire was going to the connection to the ingition switch- white connection five wires

Any thoughts?

Justin

[ChrisJC]

Well, whatever it's for, it isn't needed for the engine to run.

Maybe it fed a rev counter or someting as it would pulse once per engine revolution.

Chris.

[ramon alban]

I have traced the wire and it is tee'd into the loom with the injector wire coming from an injector and going to pin 14 on the ecu?

It is a loom from a twin plenum. When I took it out the wire was going to the connection to the ingition switch- white connection five wires, Any thoughts?

Hello Justin,

That wire is Slate/Brown [SN] (near to orange - good guess) and only has one function and that is to fire No 7 injector, seemingly, except that inside the ECU pins 14, 15, 32, 33 and 11 are all conjoined and go to the output transistor that switches injectors 1, 3, 5, and 7 to earth, all together as one bank, to fire all four as required.

The extra wire Teed into that line is intended to signal the trip computer fuel flow interface which calculates the volume of fuel used to measure mpg. Although the actual connector input to the interface has a different colour wire so I assume it changes somewhere.

Another output transistor fires the other bank but with no connection to the TC.

I cant imagine why the SN wire is connected to a 12 volts white wire on the ignition switch or thereabouts unless you were mistaken and the wire was just passing by the ignition switch, locally as it were, en-route to the TC.

Anyone deliberately connecting 12 volts to that injector would have probably been experimenting or made a big "mistaka to maka" and blew up the ECU or something I can't fathom out.

One thing for sure, in my opinion, it should not be there and could account for all sorts of strange behaviour. Maybe even like the one you reported??????? but I cant really see how.

Its therefor a mystery.

Suggest you do not leave it connected as you found it but use it as intended or if no TC is required ditch it..