Inverted spark or not ?

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Inverted spark or not ?

Postby Rs2-GTi » Sun Nov 25, 2007 4:54 am

Reading the manual, my setup should use spark inverted = yes.
However, the coil got HOT, and it did spark, but not start.

So i set inverted spark = no - and it started right up.

But it says it need to be yes, but it works only with no.

So my question is;

What does spark inverted really do ? What is the difference between no and yes ?
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Postby Rs2-GTi » Sun Nov 25, 2007 9:48 am

Is it so simple that invert is driven by - and non inverted are driven by + ?
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Postby jsmcortina » Sun Nov 25, 2007 10:33 am

It all depends on whether you are using an internal ignitor (the VB921) or an external ignitor.

The setting is critical. One way will run, the other way will overheat you coil and give weird timing.

At cranking/off you can tell what is going on. If the coil is getting continual ground when the engine is off then your setting is wrong.

James
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Postby Rs2-GTi » Sun Nov 25, 2007 3:24 pm

Thank you!

Then i need to go not inverted. If on, it did not start and the coil was overheating.

But i still don't know exactley what is the difference ?
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Postby slow_hemi6 » Sun Nov 25, 2007 5:03 pm

Sounds like your coilpack may have an inbuilt igniter.
Spark inverted is dead simple. If you invert something you turn it upside down. With regards to Ms the processor its pin puts out two states +5v and 0v.
If you look at how ignition works you, 1. spend some time with the coil doing nothing then you, 2. switch the coil circuit on to charge it and 3. off again to discharge it and fire the plugs. The time from 2 to 3 is the magical dwell period people have trouble with. To achieve this switching sequence depends on the hardware in the ignition system. From the processors point you may need to go 0v for off then 5v for on then 0v for off for the cycle OR it may need to be inverted and go 5V for off then 0V for on then 5v for off. It will be hardware dependant.
Each driver could be another inversion of this signal. So with spark inverted you get correct function of the VB921 driver in the MS but if your coilpack has another driver inbuilt then the signal gets inverted again. To cure this you are having to not invert the source signal.
Cheers Luke
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