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The mkiv Supra Owners Club

Japanese Spec Injectors


Guest Terry S
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Guest Terry S

Hi Guys,

           Just a quick one for the technically gifted amongst you. I have found out that the UK & Jap spec injectors are very different. The UK are Low impedence whilst the Jap are high impedence. This basically means that the uk injectors are very controllable whilst the Jap are much more on/off. I have been thinking of some time about injector upgrades, but having a Jap car I feel I should be sticking with high impedence injectors as I don't think the Jap spec ECU is capable of driving low impedence injectors correctly. I want to fit 650cc injectors & can get these custom made in the States but I am not sure which way to go? All I was then going to do was try & lean the fuel out where necessary with an SAFC. Any thoughts?

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Im sure a few others have done this with the 550cc injectors using the UK spec injector pack thing (technical term..) and had no problems. Certainly the guys on the NZ list have done it a few times.

 

I should think Ash will come back with a technical answer shortly.

 

good to have you here at last Terry.

 

JB

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Guest Terry S

Sorry it took so long to Join JB.

 

I know about the 550cc thing, but I can't see how this controls the injectors properly. Maybe I am wrong, I certainly hope so. As I understand it at present, the UK "box" would need to completely change the signal from the Jap ECU to correctly control the  low impendence injectors

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Guest Martin F

 

Terry, Why would the UK box need to completely change the signal ???

 

Surely it would only need to buffer it so that it was capable of drivng the lower impedance injectors.

 

I would guess the signal is the same, regardless of type of injector. As i understand it the pulse width varies to allow more or less fuel to be injected, therefore for the same width of signal a UK injector would flow more fuel than the Jap injector. The amplitude should be constant regardless of pulse width or type of injector.

 

Somebody please correct me if i'm way off track here.

 

 

 

 

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Guest Terry S

As I understand it the low impedence injector has much finer control. I may be way off track here, but don't want to spend £600 on the wrong units. I think if you use a Low impedence injector on a Jap ECU it will significantly overfuel

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Now I'm looking for a "correct me if I'm wrong", but isn't this about pulse width rather than size of load.

 

If I'm right (it's gonna happen one day, I just hope I'm around to see it), the problem would be about stress on the output amp and whether it was able to drive it.

 

Ashhhhhhhhhhhh............

 

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Sorry for the delay in my response but I've gotta get JF's EVO ready for Trax and we've got an unexpected wastegate failure and he is leaking brake fluid from the master cylinder.

 

As for the MKIV injectors, the "load" the ECU sees is basically the same regardless of whether you are driving J-spec 440cc injectors or the larger 550cc UK-spec items.

 

The UK injectors have a lower coil resistance but they also have a fixed resistance in series with the coil. These fixed resistors are not. present on the J-spec car as the ECU drives the injectors directly.

 

Terry, if you would fill me in, please, on what it is you are attempting to do I'd be happy to advise.

 

Yours,

J  

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