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  1. #1
    Drift Spice
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    RB25DET ignition coil problem-HELP!!!

    Have done the engine conversion of the RB25DET into the R32 as you know already.
    Now, I'm using the Spec 2 engine, which has the amplifier built in to the coil packs themselves (not speerately like on the RB20DET engines and early spec 1 RB25DET)

    At this time I am currently unsure whether my coils have 2 or 3 wires (I'll update)

    I am possibly looking at a wiring issue or a mis-match of parts??? The parts fitted came with the engine, which include the RB25DET engine Loom, R33 ECU, injectors, etc etc etc so thus in theory it should all just work!?!

    We are checking a few wiring connections from what little wiring diagrams I could find (which include R33 ECU pinouts and 2 different whole wiring diagrams for the RB25DET-one has 3 wired coils and one has 2 wired coils)

    Now, the problem I am having as this:

    The car runs, makes good power on and off boost. BUT... after maybe 10 - 20 minutes under load of normal road driving, the coil packs burst.. 1 by 1, to the extent that it splits the side of the coil packs and the clear gooey jelly stuff starts seeping out the side

    It seems to be that if the car is just idling, it's fine, and will continue to do so without problems.

    Now knowing that skyline coil packs are about as usefull as a chocolate teapot, I thought it may have been flook when it happened the first time, replaced the coils to see if it was those at fault..low and behold-it did it again. Same problem, same extent...

    So...

    It can't be the coils themselves, there must be something wired/earthed incorrectly which is what I am trying to find out. But I have a few questions I was wondering whether anyone could tell me.

    So, first off..has anyone else encountered this problem..? Albeit from a conversion or not???

    Secondly is there anyone in Kent (preferrably local to Sevenoaks) who has R33 gtst that I can have a look at to compare to mine (whether spec1 or spec 2)

    Next Q is a little more complicated... I would like to know what signals to expect to see at the coil plugs for both the 2 wire and the 3 wire (obviously once I know which number of wires I've got I can use the relevent answer)

    On 2 wired coils, clearly 1 is earth and the other is positive, 1 of these 2 wires will be the switch trigger, voltage readings with ignition on and engine running would be a good start, along with the corresponding wire colours.

    With regards to the 3 wire coils, the same applies, but it would be nice to know at least what current reading goes down the 3rd trigger wire (I think this is the white wire). Ideally I need the dwell time or at least a simple voltage reading for this wire. With this info I can cross reference it easily with mine and pin point the problem quicker.

    In a nut shell I have had the problem explained to me as follows, the charge time of my coils is to long and the discharge time to short (dwell time) this could be due to a missing resistor or cap in the loom or a missmatch of parts that would be highlighted by the results from a simple voltage test.

    Another point, is the voltage stepped to the coils? ie 5 or 6 volts or std 12v as I dont know and can check mine when I know what it should be.

    Anyone help? But please, I'm asking specific questions and want to try and keep this thread as tidy as possible so I can take reference from it, so please don't post if it's irrelevent. I don't want to confuse myself any further lol.

    Thanks in advance

  2. #2
    Ken Block???
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    I'm not sure that the description of dwell and discharge time are spot on.

    The coil charge time (also known as dwell) will be around 1.9 to 2milliseconds on a Nissan coil. The discharge time is how ever long it takes for the coil's charge to breakdown via the spark plug. The only thing that is controllable is the dwell/charge time, and if this is too long you'll find that the coils get very hot, the resistance on a primary coil is very low and can draw huge ampage.

    The first thing you need to do is to fuse the power feed to these coils - then as you're working on whats wrong you will be replacing fuses rather than coils.

    A two wire coil will be just +12v and ground, ground is switched via a transistor (ignitor). I'd never advise back probing a coil because of the voltage spikes you get when the coil discharges. In this case the ECU grounds the coil for the charge time, then when the ECU switches off the transistor the coil dischages via the plug.

    A coil that has a built-in transistor is driven differently - there is a +12 feed, a ground and a control wire. The control wire will be driven by the ECU and uses a lot lower current than the two wire type, some use a 5v control but 12v is most common. The control line is held high (+12v) until its time to charge the coil, at which point the line goes low for the charge period, then goes high again. You should be fine to back probe the amplifier control line as its a low current with no back emf to worry about.

    Hope this helps

    Rob
    Quote Originally Posted by Petter Solberg
    I`m driving round the corner, and crash in the christmas tree.

  3. #3
    doughnutter
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    I'll have a look in abit what mine are cause i have a 96 spec 2 gtst

  4. #4
    Drift Spice
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    thanks guys, everything taken into consideration

  5. #5
    Drift Spice
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    Quote Originally Posted by PhatBob View Post

    A coil that has a built-in transistor is driven differently - there is a +12 feed, a ground and a control wire. The control wire will be driven by the ECU and uses a lot lower current than the two wire type, some use a 5v control but 12v is most common. The control line is held high (+12v) until its time to charge the coil, at which point the line goes low for the charge period, then goes high again. You should be fine to back probe the amplifier control line as its a low current with no back emf to worry about.

    Hope this helps

    Rob
    If anyone could possibly tell me what voltage this drops to I think that would be of great significance in my quest to solving this problem (bit in bold above)

    As again I can compare my readings with someone elses that actually work lol

  6. #6
    Drift Spice
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    ?????

  7. #7
    Kit
    Kit is offline
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    Quote Originally Posted by ducatichick View Post
    ?????
    Electronics suck... i'll see if I can find out anything for you, I won't see the guy i'm thinking of until Wednesday though Bex.
    RWD V8 Hilux Mk2

  8. #8
    Ken Block???
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    Quote Originally Posted by ducatichick View Post
    If anyone could possibly tell me what voltage this drops to I think that would be of great significance in my quest to solving this problem (bit in bold above)

    As again I can compare my readings with someone elses that actually work lol
    Drops to 0v or close to it - you do need a scope for this though as a DVM isnt quick enough to show the drop.
    Quote Originally Posted by Petter Solberg
    I`m driving round the corner, and crash in the christmas tree.

  9. #9
    Drift Spice
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    cheers guys, all input has been heard loud and clear and greatly appreciated

 

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