Problem With Emanage Blue And Toyota 315cc 3SGE Pink Injectors That Are Stuck Open! - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-24-2011, 02:38 PM   #1
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Default Problem With Emanage Blue And Toyota 315cc 3SGE Pink Injectors That Are Stuck Open!

Been trying to get some Toyota 315cc 3SGE Pink injectors to work as they are all stuck open as soon as the ignition is turned on.

Car is a 1995 1.8L Eunos Roadster with an EManage Blue I spliced into the cars ECU harness.

I have triple checked all the wiring a couple of times and it is correct as far as all the wiring diagrams I can find on the net.


I think either:

the injectors are grounded causing them to stay open,

or the two wires to the injector needs to be swapped around?



Anyone else using Toyota injectors?
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Old 08-24-2011, 02:42 PM   #2
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I bet you have a ground fault. That tends to happen when you introduce one.
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Old 08-26-2011, 09:16 AM   #3
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I have not been able to find any ground fault...


I'm still wondering if anyone can tell me with Toyota injectors did you just plug them in or did you have to rewire the two wires to the injector plug i.e. swapping them around?
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Old 08-26-2011, 06:57 PM   #4
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Update is the wiring seems good. I tried wiring an injector the other way around, it made no difference and still was open.

After a few hours I got fed up and put the standard injectors back in and the car ran perfectly on tick over and when revved. The strange thing is the standard injectors still throw fuel into the engine as soon as the key is turned on.

I'm thinking the problem lies in the fuel pump circuit as when I pulled the fuel pump relay it did not stop pumping. Weirdly the EMB power turned off though.


I don't know if this is something new or the car's wiring has been altered in the past as I never noticed if the injectors were always running before I installed the EMB.

So could it be the fuel pump relay has got stuck?

or the wiring is altered from standard?

or do I still have a ground problem, but the car can still operate the injectors when the engine is running?
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Old 09-05-2011, 03:32 AM   #5
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Did you wire-in the additional "injector harness" for the Blue by chance? It would be hard to believe that there is any relation there, but anything is possible. Also, have you checked the resistances across all of your injectors yet?
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Old 09-29-2011, 05:40 PM   #6
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Spent most of Sunday on the car after leaving it for a week to think and come back with a new approach (i.e. not triple checking my wiring for a forth time), resulting in finally finding the fault with the injectors staying open! I started by bench testing the injector and fuel system relays etc, which were all fine. I then noticed one of them the fuel system relay had the ground wire changed, which I had not noticed before as it looked like standard wiring at first.

It took some lateral thinking...... I did not have the key for the immobilizer so it did not work, but had the wiring been put back correctly on the fuel system or did who ever just rewire the relay? I stripped the car looking for the immobilizer and the cut LG wire from the ECU Pin 2T (fuel pump relay). I found no immobilizer or cut wire, so the immobilizer had never been cut into the fuel pump system relay.

After a lot more thinking and looking, I cut open the OEM ECU seals and worked the continuity through until I found the T751 component had previously blown up. So the final answer I believe is that the problem with the injectors being open on "key on" is due to the fuel pump system relay being grounded through the car body and the ground not being controlled through the ECU via pin 2T. I think this has to be the problem as I can find no other. Unfortunately this means I need another Mazda Roadster BPF3 18 881B ECU to confirm this and to correct the problem fully.

So if I could find out what the ECU surface component T751 exactly is I could try to buy one and solder it on, but a quick search on Google brought up nothing. It could go to a ECU repairer but I have no idea who.

Found only one similar OEM ECU on eBay and its not the exact same code so I don't know if its exactly right? Also seems pricey at 149?
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Old 09-29-2011, 05:41 PM   #7
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Today thought about the MX5 quite a bit and got straight on to trying to confirm the grounding problem when I got home:

Put fuel relay modified wire back to a body ground (except extended it into the engine bay so I could hear the injectors).

1 Pulled the injector relay (car off) and injectors would not run (car on), put back in and they opened = this relay works fine.

2 Turned car to on position = fuel pump on and injectors open. I then removed the fuel relay wire from body ground = fuel pump off and injectors off!!

3 Put fuel relay wire to body ground and started car = car runs fine. I then removed the fuel relay wire from body ground = fuel pump off and injectors off. Now this was hard to hear the injectors on with the car running, so I got my car stethoscope so I could hear the fuel running through the injectors and did it again. I removed the fuel relay wire from body ground = fuel pump off (but there is enough fuel pressure at the rail to be able to supply the injectors for a few seconds) and the injectors turned off!!!!!!!!!!!


Therefore as really weird as it might seem, I am 110% sure that the fuel relay being on a permanent body ground is also causing the injectors to see a permanent ground = they are open.


I still believe the car has always done this as it is only possible to hear the injectors if your head is under the bonnet, you can't hear them in the car even with the bonnet up and windows down. The fuel pump is also quite quiet inside the car even with the tank inspection cover off and carpet lifted so I could get to the wires, you can hear it standing outside the drivers side. So I would not have noticed this in the past.

I know it does not make much sense but I am sure this problem is due to the ECU's fuel pump circuit having the component burnt out. This component is controlled by two or three other large components on the board, so the ECU must control the grounding of the fuel pump relay. Otherwise the fuel relay would have been grounded to the body at the factory.

Unfortunately I don't have the experience to work out exactly what this OEM ECU circuit is doing or even think I can work out what the components are!


The only thing I could do is cut the Emanage out of the wiring loom, put it back to standard again and see if the problem is still there. This would be a major pain in the *** though and would take a good couple of hours to do and re connect the EManage by soldering the wires (I'm not too keen on the idea of bullet type connectors for this).


I wonder if there is anyone local (Dorset, U.K.) who could lend an OEM ECU for a quick test?
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Old 10-13-2011, 06:01 PM   #8
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Problem solved !


"junk yard dog"

http://www.mx5nutz.c...p?showuser=3617

has got a replacement OEM ECU to me at a good price that has fixed the problem, as I had put the wiring back to standard for the fuel pump relay LG (light green) ground wire.


Thanks for all the helpful replies.
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