New ignition modules came with an odd little tube of stuff stamped 'silicone' ... where is it supposed to go? On the metal underside of the module to improve heat transfer to the metal bar they rest on?

 

Yes, It is a die-electric grease that helps in the transfer of heat.
Some Ign. modules like the older GM one would not last 10 min with out it.

 

I'm following this b/c I'm curious what symptoms caused you to R&R? I wonder how you know these are bad, like what DVM readings?

Other threads have said there is supposed to be a heat transfer paste between these and the metal surface so this must be it. I've not done it.

 

Be careful when removed these from the metal bar they are screwed to. After time that silicone will harden and act like glue. If you simply pull up on the module you will separate it & destroy the part.

They are kinda cool looking inside, but that little experiment cost me some $$$

 

BTDT.

Also, if you want to run non-resistor plugs, use only the stock Bosch amps!

Aftermarket (Hüco Ignition Units) have an aluminum base (Bosch have steel), and have trouble with EFI, I found.

 

Wow, thanks Ken for posting that! I'm having a bunch of hesitation and stumbling with my new ones. Would never have known why!

And Btw, didn't find anything under my Bosch originals, not even a trace.

 

You only need a smear of the siilcone between the base plate of th module and the frame of the car. Too much will act as a themal insulator... I know someone who used too much and the module overheated in a few minutes.