Advice?
- Thread starter DivineE
- Start date
For clarification I'm just going to lay down my understanding of how this ignition system works. Its a CDI ignition system, so it uses a high voltage capacitor to drive a high current through the primary winding of its ignition coil. This causes the coil to act like a transformer increasing the voltage by say 100 times and creating a spark. This must be a different type of coil to the normal indutive coil used on the 944? It looks like you have COP's from the pictures. I take it they are a special type of coil for CDI ignition...
Rick did have a different MSD box before swapping to coil on plug http://www.cannell.co.uk/944%20Turbo%20-%2078.htm Not sure if the COP needed it or if there was another reason for the swap.
I think they may be 996 turbo coil packs, but a long time since we talked about them!
Tony
I think they may be 996 turbo coil packs, but a long time since we talked about them!
Tony
sawood12
New member
I seem to remember they are off a Suzuki motorbike or something like that as the thread and their length was right for the 944. They needed some form of modification to make them fit. They are definitely not 996 coil packs. Those things are huge and they wouldn't fit under the bonnet.
sawood12
New member
This charts his development of the CDI (and WUF in general) in pictures. I'm sure there was some narrative to this at some stage. I read about the plug modification on his long running thread on this forum. I've just done a search but wasn't successful in finding it.
http://www.cannell.co.uk/944%20Turbo%20-%2069.htm
http://www.cannell.co.uk/944%20Turbo%20-%2069.htm
ORIGINAL: peanut
when you say' ignition box' what do you mean exactly ?
Are you referring to the ignition amplifier which receives pulses from the ECU and provides the HT spark to the coil ?
A picture of the part would be useful for positive identification.
is this the part ?
Ignition Amplifier? I don't have one of those - just an empty bracket. Why??
peanut
Active member
yes yours may have been re-positioned or have been located elsewhere originally. My car is an S2 which model is yours ?
Here is a full explanation of what the Ignition Amplifier does below. Its failure is frequently the cause of a 'no spark' situation
'It contains the high current / voltage transistors required to drive the ignition coil and has a metal back for mounting onto a heat sink to dissipate the heat generated by it. The module has its own 12v feed, and ground, and is only linked to the ecu by two wires - one from pin 24 which is a reference ground and another from pin 25 which is the control line.
When pin 25 is low, the module is turned on and will be holding the coil -ve supply low to charge the coil. When pin 25 goes high the module will turn off and cause the coil to also instantly turn off, causing a spark to be generated. By delaying how long after the spark line 25 stays high, the dwell can be varied to limit unnecessary power losses at low rpm.
The actual coil current limiting is still controlled by the module itself though. The signal for pin 25 is generated by a capture compare unit within the micro controller causing an interrupt to instantly change the pins output level when the the timer value matches it. The ecu uses a transistor to buffer the micro output which is either shorting pins 24 to 25 or open circuit.
edited to remove reference to Ford parts
Here is a full explanation of what the Ignition Amplifier does below. Its failure is frequently the cause of a 'no spark' situation
'It contains the high current / voltage transistors required to drive the ignition coil and has a metal back for mounting onto a heat sink to dissipate the heat generated by it. The module has its own 12v feed, and ground, and is only linked to the ecu by two wires - one from pin 24 which is a reference ground and another from pin 25 which is the control line.
When pin 25 is low, the module is turned on and will be holding the coil -ve supply low to charge the coil. When pin 25 goes high the module will turn off and cause the coil to also instantly turn off, causing a spark to be generated. By delaying how long after the spark line 25 stays high, the dwell can be varied to limit unnecessary power losses at low rpm.
The actual coil current limiting is still controlled by the module itself though. The signal for pin 25 is generated by a capture compare unit within the micro controller causing an interrupt to instantly change the pins output level when the the timer value matches it. The ecu uses a transistor to buffer the micro output which is either shorting pins 24 to 25 or open circuit.
edited to remove reference to Ford parts
Oh, ok.
I guess the same feature is in the BMW version - I believe some models of a similar era to ours actually had this enabled and ran twin coil packs. Wonder if it would be possible/what would be involved in adapting one....
Anyway, at least I now know what the bracket is for - nothing, it's just a shared inner wing part with the S2 I guess.
I can now go ahead and cut it off to make space for a big filter! [
]It's not possible with the lux/turbo's ignition circuity. Its very specifically designed for use with a single coil and distributor. I'm designing my modifed DME board to support dual ignition outputs for wasted spark. This isn't somthing thats possible with the standard DME.
Chop away! Looking forward too seeing lots of pics from your turbo swap!
Chop away! Looking forward too seeing lots of pics from your turbo swap!
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