In Reply to: Re: Replacing T-5 Direction Ignition Cassette with T-7, SWEDECAR [Profile/Gallery] , Sun, 1 Jan 2006 12:35:38

Thank you for posting that, and the Revisions. I agree that working on a customer's car is a lot different than when we experiment with our own, which is really all I wanted to do, try it.

On that list of differences, I would say the main concern would be the knock sensing. I have no idea how that works except that it depends on the conduction properties of the gasses ionizing in the cylinder... Do the two models use a spark plug with a different resistance spec too? hmmmm... I can see the plug and the module having to be designed to match... something to look into.

The inductance and voltage is of little concern, because the power supply goes through the transformer (the black box that is visible when you take the plastic cover off), and the circuit has to be tolerant of a fairly wide range of sparkplug gaps (the voltage required to form a spark varies with the gap).

The trigger signal emi susceptability, ditto. I can't believe they would make it intentionally worse in the new module, but who knows. In any case, if the trigger does not work, you would know in a hurry.

The charge and discharge circuits are internal to the module, and likely to have an effect only on the life of the electrolytic cap (the cylinder that is mostly buried below the black potting compound). I am assuming that after a few years exposure to heat, the leakage on this type of capacitor gets high enough that there is too little stored charge to fire the ignition properly. The way my two particular cassettes failed (multiple random misfire at high rpm) seems to suggest not enough charge to form a spark. Too bad you cannot replace the capacitor, it is probably worth all of about $2... oh well.



posted by 68.74.19...

• Replacing T-5 Direction Ignition Cassette with T-7, Gerald, Sun, 1 Jan 2006 05:53:59
  • I would not even consider it..., bill h., Mon, 2 Jan 2006 07:44:26
  • Re: Replacing T-5 Direction Ignition Cassette with T-7, SWEDECAR , Sun, 1 Jan 2006 12:35:38
    • Re: Replacing T-5 Direction Ignition Cassette with T-7, CarpeSaab, Sun, 1 Jan 2006 14:29:01 <-- Viewing This Message
  • yes, but which T7 cassette?, CarpeSaab, Sun, 1 Jan 2006 09:04:29
    • Re: yes, but which T7 cassette?, SWEDECAR , Sun, 1 Jan 2006 12:53:07
  • Re: Replacing T-5 Direction Ignition Cassette with T-7, trragtops, Sun, 1 Jan 2006 08:37:12
    • Black DI for over 35K km on my 99 9-3, Mark, Sun, 1 Jan 2006 10:43:29

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