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Thread: TPS Connector and Injector connectors off mk1a please

  1. #31
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    Cheers Jimi!

  2. #32
    MR2 Obsessive Sweetpea's Avatar
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    Quote Originally Posted by Evo4Jon View Post
    Looking at other circuit diagrams I can see that on the AE92 the wire that feeds to the injectors carrying 12v (bat voltage) splits off prior to the Solenoid Resistor and connects to the ECU through the BR terminal and the Transistor on the board must help to drive the injectors.
    Sorry chaps, I'm not fully understanding that.
    My understanding is that the injectors have +12 volts (via a dropper resistor AKA Resistor Solenoid) on one side and are switched to ground on the other side by the ECU. So an extra feed of raw 12V to the ECU on BR terminal can't be helping fire the injectors. You'd need 'more ground' for that. Or have I missed something?

    James
    There's no rust on my car. But there are some sizable holes where the rust fell out.

  3. #33
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    Have a look here:
    http://club4ag.com/tech-data/tech-sp...dentification/

    Pin 10 Is BF and the wire colour is Yellow. The description says Power from Run position to ECU and main injectors

    If you open up a 17070 the pin 10 is also marked BF.

    Do you concur with my findings ?

    I think the extra 12 Volts is to feed the injector circuitry in some otherway - maybe to power the extra power transistor to share the load or to stabilise the PWM circuit??? I am guessing. I wish Jeremy Ross hadn't disappeared off the face of the earth ! I can only conclude that he must have passed away to have been so passionate and no longer posting anywhere in the net
    Last edited by Evo4Jon; 19th January 2017 at 02:10 AM.

  4. #34
    MR2 Obsessive jimi's Avatar
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    The extra feed may allow more current to flow as it's bypassing the resistors (which I think are there to limit the current)
    Haven't managed to get any more info on the red injectors .. yet. Did find this via the EPC

    Black is not a colour ! .... Its the absence of colour

  5. #35
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    interestingly, that link I posted above shows the AE86 ECU probably for a bluetop with TVIS - same as the earlier MR2's. My Mum used to have an AE86 (corolla Coupe 1984 model) and when I was about 20 I used to borrow it alot. That engine was SO rev happy. It used to charge to the red line so freely, I was always hitting the rev limiter. I just want my MR2 to feel a bit closer to my AE86 experiences

  6. #36
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    Sorry, was going to reply yesterday but spent the night trying to find what the BF terminal was for...

    So - I agree that you need to connect the BF terminal to the positive feed to the injectors just after the 'fail safe' relay.

    I did find this...
    "For fail safe starting, you may also need to give power to injectors (Yellow wire found on 10Pin plug, Pin 10 (BF)) by joining a wire into the yellow wire and giving it 12V on iginition"
    ...here
    http://www.ae86drivingclub.com.au/fo...1-Wiring-guide
    Which might be worth a read if you haven't seen it.

    Personally I'm just not convinced that BF has anything to do with the injectors apart from pinching power from them.


    Quote Originally Posted by jimi View Post
    The extra feed may allow more current to flow as it's bypassing the resistors (which I think are there to limit the current)
    The resistor is indeed there to limit, or rather reduce the current in the injectors. Or, looking at the other side of the same coin, reducing the voltage across the injectors.
    But the BF terminal can't be there to bypass the resistor because as far as I can see the 17070 ECU was used with high impedance injectors and no resistor. I searched the 'net all last night and couldn't see what BF was for. Probably doesn't really matter. Just wire it up and go for it!
    There's no rust on my car. But there are some sizable holes where the rust fell out.

  7. #37
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    I think the red injectors on the mk1b crossover are low impedance with the resistor pack. I say this because i recall reading a post where someone ran their mk1b on both 17070 and 17140 ecus ( as I have done) but they then tried an earlier 17030 ecu and when they revved it past 3000 rpm a fuse blew and the engine cut. I concluded that the mk1a must have high imoedance injectors and the 17030 could not take the current from trying to run a mk1b with low impedance injectors

    Thanks for the extra info Sweatpea ☺
    Last edited by Evo4Jon; 20th January 2017 at 11:04 PM.

  8. #38
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    Just when I thought I was getting the hang of it...

    So I've got an engine manual that shows an ECU with a BF connection but no injector resistor pack. In fairness I think it was for a Corolla and who knows which model ECU it was.
    And also Jimi's part numbers in post 24 show the 17070 ECU with the early injectors - and presumably no resistor.

    Maybe the 17070 could drive either type but the 17030 couldn't. But then I'm sure Jeremy Ross said (in his "lifting the lid" article) he'd run all 3 ECUs on a MK1b car with no problem...

    This'd all be a lot easier if Toyota put the part number of the ECU on the wiring diagrams.

    James
    There's no rust on my car. But there are some sizable holes where the rust fell out.

  9. #39
    MR2 Obsessive jimi's Avatar
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    Part of the problem (in figuring it out) is that I can't find a 1987 diagram to confirm the presence (or lack) of a resistor pack. Perhaps someone who has 1987 could check their ECU number and whether the resitor pack is present. Also reread Jeremy's article and found this
    As mentioned in a previous article the wiring for the mixture screw appears different for the various mk1 types. The 89661-17140 mk1b uses a different ECU input pin number for the mixture screw. Although I don't have access to the other mk1 types (to look at the wiring) it appears that the 89661-17030 and 89661-17070 ECUs use a different input pin. This means that the ECUs are not 100% interchangeable and I would guess the wiring looms will differ in this respect too. If I put a 17030 or 17070 ECU in my 17140 mk1b then the mixture screw will not work. The car runs OK otherwise.
    and this
    I fitted an mk1a 89661-17030 ECU to my t 'test' mk1b,
    Black is not a colour ! .... Its the absence of colour

  10. #40
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    I found the post I had read a while back:
    http://imoc.co.uk/forums/viewtopic.p...734f6c98bfba47

    "Hi Ian,yep tried a mk1a ECU in a MK1b, it wil idle perfectly, but as soon as you open the throttle some rather large fuses blow [Shocked]"

    Jimi I have just re-read your table and realised that the injectors 16010 substitute is 16090.

    This does mean that the grey injectors 16010 (mk1a) and the 16090 Red are the Mk1b Xover are interchangable which suggests that the 17070 is indeed expecting to see high impedance injectors !

    Hmmmm

    I have ordered a set of Red injectors and grey ones so all will be revealed !
    Last edited by Evo4Jon; 21st January 2017 at 11:23 AM.

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