Thunderbolt V system with two sparks per pass of the sensor wheel

[eyekandyboats19]

Hey there.
first time poster from Ontario Canada!

I have a quick question with use of the older thunderbolt V system.
it uses a hall effect sensor in the ignition system as well as a sensor wheel.
eveytime the sensor wheel tab ( 1 of 8 tabs) passes the hall effect seonsor , i get two spark events right after eachother very quickly. I thus 16 spark events per a full cycle of all 8 cylinders
Is that normal or could the module be failing?

 

[nimrod69]

Re: Thunderbolt V system with two sparks per pass of the sensor wheel

Could be to insure no unburnt fuel exits?????

 

[HT32BSX115]

Re: Thunderbolt V system with two sparks per pass of the sensor wheel

That's a good one.....

I'd have to try mine to see if it does it also.

In any case, it wouldn't hurt anything as long as the first "one" came at the correct time!

 

[eyekandyboats19]

Re: Thunderbolt V system with two sparks per pass of the sensor wheel

thanks guys!
its not having a running issue. Just inquisitive minds want to know
lol
i do beleive tho that the two sparks might be a technique for unburnt fuel.
i have the service mannuals and checked them, nothing in there about it.

 

[Maclin]

Re: Thunderbolt V system with two sparks per pass of the sensor wheel

Multiple sparks at idle and lower rpm's are beneficial in lighting off the mix. At higher rpm's ignition of the mix is actually easier to accomplish and single sparks work well. The MSD brand ignition systems do just that, they have a capacitive discharge for higher voltage at the coil and provide multiple sparks varying by rpm. The "MSD" brand name is short for Multiple-Spark Discharge and is their reason for being.

I do not know if a Thunderbolt system does multiple sparks by design or even if it is a CD type system, but usually without a CD (capacitive discharge) "storage" bank there is not enough time available to get the coil to build energy and produce sparks close enough together to be worth it. A non-CD system has to rely on how fast a coil can build up the charge and then spark while the CD systems have an ample voltage store ready to go under computer control. They can hit the coil at any time with a "shaped" higher voltage shot and get the coil to react much faster.

 

[Maclin]

Re: Thunderbolt V system with two sparks per pass of the sensor wheel

I found this from a CDI vendor that supplies replacement/improvement units for Mercs, this would indicate that the Thunderbolt is a CDI type and may use multi-spark techniques.....

"The original Thunderbolt ignition was a very good CDI & represented the state-of-the-art system from the 1970's. Even today, it's better than most factory units. "



http://www.hewtechelectronics.com/sledparts/MERC-LC.htm