Digifant CO problem

Discussion in 'Engines' started by rubjonny, Sep 9, 2005.

  1. Carl loader Forum Member

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    Cheers rubjonny, knock sensor is new so i can rule that out and tightened to 20Nm. Timing is spot on as far as im aware (6 degrees btdc), but it did used to pink a little when accelerating under load, even with optimax fuel (which is what i always use). I have got rid or it now by just tweeking the timing a tiny bit, take it for a blast, see what its like, and adjust again if necessary until it sounded right

    Ill just get a gas tester and set it all up myself until its as best i can get it

    Cheers again :clap:
     
  2. Gti1990xyz Paid Member Paid Member

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    Hi,

    could someone look at MAF sensor Fig. 7-21 of this guide ( https://vwts.ru/vw_doc/eva2/FU01/ch7.6.html ) and tell me a few unknowns that I cannot find online;

    1. My CO is 8.9% and MOT limit is 3.5%, how many turns anti-clockwise is required?

    Reason I ask is that I turned it 4 turns anti clockwise and it justs feels like it doesn't have any resistance, I turned it back to current setting.

    2. Is there a quantity of turns from fully closed to fully open? (EDIT: found more info, this is just possibly a needle valve or like opening a tap so no problem turning it forever or to fully in or out, my worrk was it was somehow connected to the moving parts of the electronics in the AFM)
     
    Last edited: Oct 2, 2023
  3. Gti1990xyz Paid Member Paid Member

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    Mk2 golf digifant 8 valve GTI 1990

    MOT tomorrow.

    Decided to look at timing, ISV, blue sensor resistance, CO screw on AFM and idle speed. Somehow I have managed to clear up the excessive smoke (possibly why my MOT failed at 8.9% CO.

    Changes;
    • Fully un screwed CO screw on AFM, discovered threads bump at 12 turns. Wound it in to about 8 turns open.
    • I had a shot of redex in with 5l of premium fuel.
    • I looked at timing, I think I had it previously at 6 deg After TDC instead of 6 deg BTDC. I picked up that rotar arm rotated anti clockwise weeks ago and thats why I had it wrong. So i adjusted that, so rotar arm tip center is now 3.4mm before (anti clockwise) the mark on the distributor body. --- is it wrong to use the center of the rotor arm contact

    Scribble of rotor arm =o==) if the bracket symbol is the copper part going to each cylinder, where about should I use for timing? i used middle, but thinking about it, perhaps the top is best as that would allow an advancement of timing? (read somewhere 30 degrees advance).

    Checks;
    • I cleaned out the ISV with brake cleaner and cotton buds.
    • The blue temp sender is 207 ohms at 97celcius (using heat thermometer pointed at sensor body).
    • Checked engine RPM, hot engine seems idles at 850rpm.

    NOW I THINK it runs too lean as seems under powered and virtually zero smoke.

    Any advice appreciated.
     
  4. KeithMac Forum Junkie

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    You need to use a timing light on the Flywheel really, in static ignition timing mode and adjust until the markers line up.

    A Wideband AFR meter is a godsend, I wouldn't be without one now.
     
    daNpy likes this.
  5. daNpy Forum Member

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    Exactly, without any measurement you're not easily gonna find what's wrong.
     
  6. Gti1990xyz Paid Member Paid Member

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    Hi Thanks for the reply, had a nosey at the AFR, looks good but if I can keep it stock I will stay that way. Timing wise, my flywheel doesn't have the 6deg BTDC punch mark or V notch. Instead it just has a 1cm or so square so I cannot use a timing light which I own.
     
  7. daNpy Forum Member

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    But you can mark the flywheel yourself so at least you'll know where you are to begin with :)
     
  8. KeithMac Forum Junkie

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    Mark flywheel or accessory belt pulley.

    I use a degree wheel to set base timing.
     
  9. KeithMac Forum Junkie

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    I use a Zeitronix ZT-2 and if I don't need to look at display it sits in the "Service Bool Holder" perfect fit. LCD Display
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    KeithMac likes this.

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