ECU woes (Help wiring etc)

[GTti]

This is not my sort of area so I need some help here!


Ok I have my ECU wired into the car, I've wired the ECU in to a 12v ACC wire.
When in the ACC / ON position all sensors (MAP, TPS, ATS, CTS) seem to be reporting properly.

Fuel pump relay drive is wired from the stock ECU loom so I know is correct. I've double checked power to the injector loom.

Now I believe the Omex can control the coil without the use of the OEM ignitor pack - so I've made the coil a 12v feed and the -ve is wired to the ECU to break the ground and control the spark...

Now the problem that I have.

When I go from ON > ST position, the power drains and the ECU goes offline. When the key goes back to the ON position after attempting to crank over the ECU comes back online and I briefly get A spark and the fuel pump primes.

So it looks like the power is being drained somewhere, the effects are seen on my other ACC wires components (Clock goes dimm almost off, wideband goes _ _ _).

For information the injectors and coil power are wired into the stock loom 12v battery feeds - not ACC)

 

[HYBRID]

hmm.. im betting its got to do with the way uv setup the coil... what does the ecu handbook say about how uv wired it up? sounds like its pulling the current

 

[GTti]

Well what concerns me is that the fuel pump doesn't prime when ON which seems strange even if something was draining power.

The wiring is as follows: (Aux is fuel pump relay)

 

[GTti]

Perhaps I should wire the coil into an ACC feed as I think at the moment it's feeding from the main relay?

 

[Texx]

Most cars have a cranking break relay to kill most electrical components while the engine is being started, thats why your radio usually goes off when cranking the engine. I would check your live feed to the ECM during cranking and confirm if it a voltage drop or voltage cut, you may need to take a live feed from somewhere else, I would suggest using the original ECM feed.

With regards to the fuel pump, again have you checked you get a live feed at the pump when the ECM is powered on? Surely the pump should be wired through a make relay not directly from the ECM? If this is OK, can only be the earth feed.

 

[GTti]

Ok will do for the ECU - sounds good.

Fuel pump relay wise, I checked the stock wiring diagram and the wire I'm using deffinately goes to the relay. So I can't think what problem I would have created there.

 

[Texx]

Ok will do for the ECU - sounds good.

Fuel pump relay wise, I checked the stock wiring diagram and the wire I'm using deffinately goes to the relay. So I can't think what problem I would have created there.

Is the pump relay switched by an earth or live? Its difficult to understand without seeing a wireing diagram for the original car..

 

[GTti]

Is the pump relay switched by an earth or live? Its difficult to understand without seeing a wireing diagram for the original car..

Have a look at this PDF, at the end you see CB-80 EFI ECU, follow PIN 4, as far as I can see this goes to the relay which does appear to be switched by a live unless I'm mistaken... (Please feel free to check )

[edit] PIN 1 , 22 are 12v feeds from battery.


http://www.oakleaf-rm.demon.co.uk/g100wiringdiagram.pdf

 

[Texx]

I take it the main relay is still in place and you have a good earth at E1?

 

[GTti]

I take it the main relay is still in place and you have a good earth at E1?

Yup main relay has been left un touched, earths are solid - never had a problem before I took the OEM ECU out.

 

[HYBRID]

Perhaps I should wire the coil into an ACC feed as I think at the moment it's feeding from the main relay?

yes thats correct! the coil does not engage (warmup) before acc

 

[Texx]

You have a IGN feed to one side of the pump relay coil, so the ECM must switch the earth on pin 4.

 

[GTti]

You have a IGN feed to one side of the pump relay coil, so the ECM must switch the earth on pin 4.

Yup, thats how I believe its wired. So the ECU gives the earth to prime the pump.

 

[Texx]

So does your new ECM short the blue auxiliary wire to earth or are you using a relay controlled by the ECM to earth the pump?

 

[GTti]

So does your new ECM short the blue auxiliary wire

Correct.


Sorry for delay I've been busy at work

 

[Texx]

Have you checked for a live feed at the boost pressure and idle up VSV connectors?

And I take it you've checked both EFI No1 and No2 fuses... :homer:

 

[Texx]

Also are you using the same simultaneous injection setup, or have you changed to a sequential injection setup?

 

[GTti]

Group fire only - no sequential option on this ECU, I'm heading downstairs to the garage for a play now. I think I checked all fuses, so will double check.

 

[Damage]

Is that the AEM ECU GTti ? Just setup an Integra with this ECU. Its an awesome standalone

 

[GTti]

Nope it's an Omex 550 - about four years old now.