Quote:
Originally Posted by XfireZ51
LT5-Ignition,
If you were responding to my question of all 4 coils. not working, I was posing that condition where rather than grounding the coil, that ground signal was used as a trigger for the LSx coil. I believe the IM fires the appropriate coil by grounding that coil. Now what if the IM was grounding the coil was simply converted to an ~.4v trigger signal sent to the corresponding LSx coil pairs.
There would be very little load to the IM. And now that happens for all coils. Also, what is the dwell set for the LT-5 coils and where is it controlled? CN it be adjusted?
I hope that I am being clear and would be happy to try to clarify further if I can. But think of it as the IM being converted to simply a sequencer for the LSx coils. And using what was originally the trigger ground for the LT-5 coils and converting that into a compatible trigger signal recognized by the LSx coils instead. Much less voltage. As I see it, GM took the ignition module functions and divided those functions between the coils themselves and the ECM thereby eliminating the need for the IM.
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I think understand. The LSx coils are controlled by their ECU with a 5 volt high to 0.2 volt low signal (EST signal). When the signal is high, the coil turns primary current on and when it falls the coil turns off current rapidly causing the spark. The high time (dwell) is typically around 3 to 4 ms. So, like you say, you can convert the 0.4 low state dwell time to a 5 volt high state time with a buffer chip. You feed 2 LSx coil pairs with this signal and you still have a DIS.
I can not remember the typical dwell time of a LT5 IM. I think it is shorter than 3 ms. Perhaps a Forum member knows. Is it in the service manual?
I do not think there would be a performance benefit to using LSx coils. The larger diplacement engines should not need more secondary voltage unless they are also increasing cylinder pressure at time of spark. ( increasing torque/litre (Brake mean effective pressure) ).