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328 ignition diagnostic connector

Discussion in 'Technical Q&A' started by ric1241, Jul 15, 2004.

  1. ric1241

    ric1241 Rookie

    Mar 6, 2004
    25
    My curiosity led me to look at the signals available on the ignition diagnostic connector located on the driver side of the 328 engine bay.
    After sorting out the discrepancy in pin numbering and usage between the
    wiring diagram and the diagram labeled "Diagnostic N.2" I examined the signals with an oscilloscope. (Diagnostic N.2 agreed with the wiring as found in the car). The signals available are from the TDC sensor and the primary windings of each coil. The signals are what one would expect
    (I would attach but I don't have a scope camera, any one interested can PM me for a sketch!). It seems that the TDC sensor produces two pulses per flywheel revolution and each coil one pulse per TDC pulse. Can anyone confirm that I have this right? If you have a scope this connector provides a convenient place to verify ignition system performance and a DMM with a frequency measuring feature lets you check the tachometer calibration.
     
  2. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,262
    Texas
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    Steve Magnusson
    If you check the ignition section of the US 328 OM 396/85 (about page 72) it confirms 2 pulses/rev for the TDC sensor (interestingly, they got this wrong in the 376/86 328 OM which shows 3 pulses/rev -- I think they must have used the TR schematic as the basis and forgot to change the "wheel" drawing from 3 to 2).
     
  3. DGS

    DGS Three Time F1 World Champ
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    May 27, 2003
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    DGS
    So are the two TDC pulses 90 degrees apart (TDC per bank) or 180 apart (as hinted in the OM)?

    The OM also shows 25 "pips" on the RPM sensor wheel (when way enlarged ;) ), but I got the impression (from the tech manual) that RPM was 144 pulses per rev.
     
  4. ric1241

    ric1241 Rookie

    Mar 6, 2004
    25
    The TDC pulses are 180 degrees apart. I have not tackled the rpm sensor puzzle yet.
     

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