XU9JAZ (DKZ) igniotion timing/advance
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  1. #1
    Tadpole Nighty89's Avatar
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    Default XU9JAZ (DKZ) igniotion timing/advance

    Hi,
    Which sensors ECU uses to advance ignition timing? I run mostly on LPG (BRC Blos) and i'm afraid, that ignition is not advancing when i push pedal to the metal.

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    And another question, this engine has almost standard ignition distributor, but without vacuum advancer, but there is some regulation like in standard distributor, but when I turn distributor clockwise/counter clockwise - nothing happens. Is there a way to advance timing (for LPG)?

    Engine: XU9JAZ (DKZ) taken from '91 ZX Volcane and fitted into Citroen BX, replacing the same engine. ECU, airflow meter etc. stayed the same.
    ECU: Bosch Motronic MP1.3.

    Thanks in advance!

  2. #2
    Fellow Frogger! Rally's Avatar
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    The timing is contolled by the ECU , it recives a crank angle signal from the sensor mounted on the top of the bell housing.
    If you wish to change your timing you could slot the mounting holes and move the sensor towards the rear of the car.This will not change the shape of the advance curve but will move the timing accross the whole rev range.
    Or you could replace the ECU with a programable unit or fit an interceptor type ECU.
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  3. #3
    Tadpole Nighty89's Avatar
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    Thanks for reply.

    If you wish to change your timing you could slot the mounting holes and move the sensor towards the rear of the car.
    Does that requires dismantling gearbox, or drilling in it?

  4. #4
    Fellow Frogger!
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    Moving the sensor will give you more advance across the entire range.

    LPG requires substantial early advance, but less at the top.

    More total advance will give better low speed response & performance but prevent the motor
    from revving out & even cause damage. It can also cause unacceptable problems when the motor
    is switched back to petrol.

    A dual curve system is the ideal solution so you can switch between the two, or if on gas only,
    a system with a LPG curve.

    Cheers, Richard

  5. #5
    1000+ Posts PeterT's Avatar
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    Try fitting a chip from an Mi16 (must be 3 row 1.3). They have less total timing and more down low. Should be better with LPG. Also, I have Mi16 chips which have less again up top and even more down low. They're $45 + postage. I also have standard chips you can try for free.
    Last edited by PeterT; 6th January 2012 at 09:04 AM.

    '92 205 Mi16
    '90 Mi16x4

  6. #6
    Tadpole Nighty89's Avatar
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    By chips you mean ECU?

    I use this car for long distance travelling, so i drive only on LPG i even start cold engine on it. Yes, i know it's not recomended, but i know what I'm doing.

    Thanks for offer, but as You see I'm from Poland, so it's not an option. We have a lot of Mi16 on our used market. :-)

    Why am i troubling with all this? On standard road, driving under 3000RPM (city etc) and LPG my car drive like an 1.6, on petrol it has like 40 more HP, but accelerating with pedal to the metal from 0-100km/h on LPG is almost the same as on petrol. LPG installation is fine.

    EDIT:
    Is it possible to mount standard distributor with vacuum ignition advancer e.g. from XU5? What besides distributor would I need?
    Last edited by Nighty89; 6th January 2012 at 09:48 AM.

  7. #7
    1000+ Posts PeterT's Avatar
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    By chip I mean the actual ECU chip itself. This contains the fuel and ignition mapping. Open the case up and change it, like this:

    http://www.taylor-eng.com/ecu/case_opening2.html

    The picture is of a 2 row case, 3 row is very similar.

    What does it matter if you're in Poland?

    I had a Nissan Patrol which I drove on LPG only for 300 000+Km. The metallurgy in XU engines is equally as good. ie hardened valve seats and bronze guides.

    '92 205 Mi16
    '90 Mi16x4

  8. #8
    Tadpole Nighty89's Avatar
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    Okay, i will go into deprecating the ignition system, by replacing ignition distributor with one that has vacum ignition advancer/retarder. At least for now, to see if there's a difference.
    I have spare one from a TU3 engine - it fits just fine in XU9, but will it work correctly?

    PeterT: i've done what You said, and replaced the chip with the 16V one (from BX), and there's not much of a difference. I'm afraid i have wrong/damaged ECU.

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