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Old 03-16-2012, 08:40 PM
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Bluegrass 7
Bluegrass 7 is offline
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Let me add something that may be of interest.
Any other coil has no real life history by compairison to the OEM units..
Buying high output coils in the hopes of gaining power will never happen on a stock motor.
All a coil needs to have is enough reserve voltage to fire the plugs under the worst conditions of EGR operation and erroded plug gaps to a reasonable degree before some type of service is needed.

To have higher voltage available from a coil is of no benifit.
The reason why is as follows:
Under normal air fuel mixtures in the 12 to 15 range, the voltage needed to fire accross the gap is always a function of the mixture density and to some degree cylinder pressure.
This requres in about the 7 to 10,000 volts range.
When the EGR is called to open, the mixture goes up to the 20 to 1 range.
Since this results in less density in the gap area, it requires 20,000 or more volts to cause the spark to jump the gap so you see voltage requirements go up drastically.
Here in, if a coil has low output, a missfire results as was the OP case above.
Bottom line is high output coils above about 40,000 volts on a fault free motor has no benifit.
To finish with a possible qustion that is often asked. If the plug only needs 7 to 10,000 volts to fire a normal mixture, what happens to the rest?
At the time the spark jumps the gap, the low resistance offered in the Plasma in the gap shunts down the coil output such that the voltage cannot rise any higher than the breakdown value and is lost.
This means the absolute voltage required is density dependent.
Installing coils of any higher output than what is needed withsome reserve has no benifit.
Power comes from the BTU content of the fuel in any given motor design.
Good luck.