Mk1 with ABF - Totally new fuel system and it STILL wont start! Help!

Discussion in '16-valve' started by Hilux, Jan 23, 2011.

Page 3 of 4
  1. tshirt2k

    tshirt2k Forum Junkie

    The relay should click all the time. It may be faulty. Low battery voltages can damage relays by burning contacts.


    Can you just earth pin 28 so the relay is energised all the time whilst doing your tests? It will save time turning the ignition on and off to get it powering up for a second or 2.

    I cant see how the relays operate when not connected to the fusebox but not when plugged in.

    The later ABF ECU dont use pin 28. Tape it up as it doesn't need connecting.
    The lambda and injectors are powered directly from the FPR and are fused.

    You can connect pin 30 supply directly to the pin 87, Which i assume will be the lambda/injectors. This will effectively bypass the lambda relay as per post '94 ABF's. If this works i would remove the wiring for the lambda relay and add some fuses for lambda and injectors.
     
    tshirt2k, Feb 20, 2011
    #41
  2. HILUX

    Hilux Forum Member

    Exactly thats why I am completely baffled but its true!!! They operate with the fuel pump bridged as well (which has me totally stumped as to why?)

    On the wiring diagram below on section 41/2 its shown from the Lambda relay J208 going from 85 to the ECU so I believe its an earth to the ECU. Do I need it as I believe mine is a circa 1993/4 unimmobilised ECU Mine has it and it connects to pin 28

    http://www.zen17496.zen.co.uk/downloads/g3abfecu.pdf

    Pin 87 is the lambda/injectors ignition fed supply.

    Thats it then, I`ll use a relay to power the injectors/lambda by earthing pin 86 and find an ignition feed for the black/brown (if its needed)
     
    Last edited: Feb 20, 2011
    Hilux, Feb 20, 2011
    #42
  3. tshirt2k

    tshirt2k Forum Junkie

    You dont need a relay. The feed to the (30) relay is fed from the FPR. Add a link to to 87 with a piece of wire or use the jumper wire that goes to 85. Connect that to 87 and it will bypass the relay and should power the injectors all be it for 1 or 2 secs and when cranking.
     
    tshirt2k, Feb 20, 2011
    #43
  4. HILUX

    Hilux Forum Member

    Thanks, brilliant news.

    Still uncertain about the black/brown to the ECU but I`ll leave it off and see what happens.
     
    Hilux, Feb 20, 2011
    #44
  5. tshirt2k

    tshirt2k Forum Junkie

    Tape it up. Its not needed. Does the FPR use pin 6 from the ECU to switch on?
     
    tshirt2k, Feb 20, 2011
    #45
  6. HILUX

    Hilux Forum Member

    Yellow/blue from pin 6 is connected to FPR 85 via fuseboard pin D13 which I believe is correct.
     
    Hilux, Feb 20, 2011
    #46
  7. tshirt2k

    tshirt2k Forum Junkie

    Yes. Sounds right.
     
    tshirt2k, Feb 20, 2011
    #47
  8. HILUX

    Hilux Forum Member

    I believe I now know what the issue was.

    I was assuming that the black/brown to ECU pin 28 was grounding the relay 85/86 circuit but it wasnt.

    I might be wrong as I was seeing 12v acroos 85/86 but I reckon if I simply remove the wire and earth the relay then I`ll bet the relay will work.
     
    Hilux, Feb 20, 2011
    #48
  9. tshirt2k

    tshirt2k Forum Junkie

    According to the diagram it should be earthing it. Earthing should give you the same result. If it works by earthing there may be a fault in the ecu for that pin.

    You may need to check continuity to the ecu pin 28.
     
    Last edited: Feb 20, 2011
    tshirt2k, Feb 20, 2011
    #49
  10. HILUX

    Hilux Forum Member

    Continuity confirmed.
     
    Hilux, Feb 20, 2011
    #50
  11. tshirt2k

    tshirt2k Forum Junkie

    Then it should go to earth unless ECU is faulty. Have you bypassed the lambeda relay or earthed the relay yet? May be also worth checking ECU earths on pin 1 and pin 33.
     
    tshirt2k, Feb 20, 2011
    #51
  12. rubjonny

    rubjonny Administrator Staff Member Admin

    I think it would be best to delete the relay entirely, i left it in as i thought it would be required for you as you need a higher higher wattage lambda probe for non-cat application. but looking again at the diagram its powered by the same pin on the fusebox as it would be without the relay, so its actually pointless for it to be there at all, i really dont see why vw bothered to put it in [:s]

    so in short bypass it and that should solve the problem hopefully. I'm really sorry you are having all these problems, its the only ABF loom I have made which has failed in this way! if you really cant get it going feel free to send it back to me and I'll go over the whole thing with one of them fine toothed combs you hear about, free of charge. I'll pay your postage too :thumbup:

    All i can think of is there is some loom damage or the ecu itself is faulty somehow, mine is using an early loom with the relay and it works faultlessly
     
    rubjonny, Feb 21, 2011
    #52
  13. rubjonny

    rubjonny Administrator Staff Member Admin

    ah, I've just had a thought. perhaps the ecu doesn't trigger the lambda probe relay at all times, maybe under some circumstances the relay is off. like when cranking or something...
     
    rubjonny, Feb 21, 2011
    #53
  14. tshirt2k

    tshirt2k Forum Junkie

    Maybe this is the case. But that means injectors shouldn't be fed from that. Should be fed from the FPR as per original ABF.
     
    tshirt2k, Feb 21, 2011
    #54
  15. rubjonny

    rubjonny Administrator Staff Member Admin

    well if i knew that before i did the loom then it wouldn't have been ;)

    factory CE1 has the injectors fed from E/14, which is where the lambda relay is fed from right now. i reasoned that after the relay would be a good place to get the power from. but now if it seems if the relay isnt on all the time, i should have put it before the relay instead...
     
    rubjonny, Feb 21, 2011
    #55
  16. tshirt2k

    tshirt2k Forum Junkie

    Suppose you learn something new everyday?;)

    I'm sure the injector feed could be moved. The Lambda feed is for the heater though, so unless its only on during running i would have thought it should be on when FPR is on, or maybe that the reason it has a separate earth switch?

    Are all your looms made the same?
     
    tshirt2k, Feb 21, 2011
    #56
  17. rubjonny

    rubjonny Administrator Staff Member Admin

    yeah think we need to confirm if the relay for the lambda is on all the time, or not. its just a random thought i had to explain this, as i say could still be an ecu or wiring problem.

    the relay in the MK3 takes a FPR live feed on the input side, the earth is from the ecu. i assuemd the ecu just triggered it as soon as the ign is on, but now im looking at how the relay is wired and it seems pointless that it is even there, since the input to the relay is from the same pin as it would be if the relay is not there. so that defeats the whole point of having a relay, unless of course it isnt triggered by the ecu all the time as you say.

    I used to put the fuel injector feed to the big plug N, but its not fused so i stopped doing it. not that its really that much of an issue but id rather not risk a loom fire! so now i use E/14 as per factory, which is nicely fused. thinking on it this is the only pre-90 loom i have done with the relay, the rest have all been without it and so this issue has never occurred before. Plus if i had put the injector power to one of the relay input pins then this issue wouldn't have occurred either!

    easily solved though, either bridge the relay pins to bypass it, or just chop the black/brown pin and earth it instead. that way lambda relay will always be triggered whenever the FPR is live.
     
    rubjonny, Feb 21, 2011
    #57
  18. tshirt2k

    tshirt2k Forum Junkie

    VW must have thought the same, as they also reomoved it on later cars. At first i thought they would increase wire size but they haven't.

    I noticed on the diagram when i was doing my MS that they didn't fuse the injectors either. So i had to add them in.
     
    tshirt2k, Feb 21, 2011
    #58
  19. rubjonny

    rubjonny Administrator Staff Member Admin

    I've seen 2 different digi wiring diagrams for the CE1 fusebox, some are powered from ecu relay without a fuse, some are powered by pin N which again isnt fused. sure i saw another which was powered by E/14 which is fuesd, but now im looking i can only see the lambda heater there. not like all the other power feeds to the bay are fused tho tbh so i guess it doesnt matter :lol:

    I try to wire it like CE2 which takes a fused feed for the injectors, E/14 is the easiest place as there is already a pin there plus a spare spade connector if its an injection model. if im doing a loom for a non-injection car i supply a E/14 pin with the loom with a spade on which allows the customer to use a factory FPR. they then put the fuel pump power to the spade which is easy for anyone with even the most basic of wiring tools to do :)

    Id prefer to sue the CE1 ecu relay socket, but the trouble is you need the plug R which is only available on digifant models, 9 times out of 10 i dont have it so hence the ecu relay above the fusebox. i think from now on i'll bin the lambda relay as its just another layer of complexity which isn't required
     
    rubjonny, Feb 21, 2011
    #59
  20. HILUX

    Hilux Forum Member

    John

    Its not your issue. You wired it absolutely fine but thanks for the offer.

    The main issue is that for some reason with the FPR in place I get voltage to 85/86 and it switches 3087 but it wont power 87. If I remove the FPR and bridge direct I get full volts to 87 and it all works.

    What I cant understand is why this happens as it shouldnt as the FPR is working, the Lambda relay is working, its a total mystery. I cant see how the FPR would rob anything of power as it gives a full 12volts to the FP supply which simply powers the Lambda relay.

    I will keep the Lambda relay but use it for the injectors/Lambda sensor. In this way the ECU cuts fuel and injectors in a crash.

    The other feed/earth from the ECU pin 28 is not an issue so all I have to do is remove it from the relay block and earth 86 and it should power the injectors (I think)

    All I have to do then is earth the brown/black for the ECU to work.

    At least thats the theory.

    ECU earths are fine - thats been proved by testing the continuity from the brown/black wire to car body earth (which has to pass through the ECU) and I have tested the other earths anyway.

    I consider that they are but via the fuse board from E14 which is from the FPR 87 and having tested for continuity I have found that this is the only connection I believe (or am I wrong?)

    The wiring diagram below shows a relay for the Lambda and it it shows the FPR supplying to 87 (as designated on the diagram) on the Lambda relay and then when switched to 30 and bridging to 86 but interestingly it also shows a 1.0mm bypass from the FPR which might suggest the Lambda is heated with ignition on all the time and not cut by the FPR and then when cranking and running additional wiring is added via the relay as presumeably the voltage draw increases Either one is fused by S18 (on the Mk 3 fuseboard) together with the fuel pumps.

    I may be wrong but have a look and see.

    http://www.zen17496.zen.co.uk/downloads/g3abfecu.pdf

    The Lambda is a heated element and they can break down so I`d rather they were fused and supplied by a relay and injector wiring can short out also or increased resistance at the injectors can create issues to so a relay and fuse is essential in my book

    I think you leave it in for the reasons above and simply earth pin 28

    I`ll update this weekend.

    Thanks one and all.
     
    Hilux, Feb 21, 2011
    #60
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