I have a quick question from guys over here trying to convert big turbo Escos to AEM managment. What second cable going to ignition amplifer does?


There are two going to marelli ECU from igniotion amplifier, but AEM will only accept one. What does the other one? The car will run with one of them diconnected but missfires over 5k rpm.

 

Nobody???

 

std big turbo ignition amp wiring pin out is as follows....


1 output to coil
2 gnd (0v)
3 trigger gnd from ecu
4 pos (12v)
5 not connected
6 trigger pos from ecu
7 not connected

 

OK Dave the ones that interest me are 3 and 6.

I understand one is (+) trigger and one is ground trigger. Why two are needed?

 

The cossie ignition system is very sensitive to noise on the ignition trigger lines, mainly attributable to less than perfect earthing arrangements, which gets aggravated with age. The second connection to pin3 is essentially a ground reference for the trigger circuit running directly from the ECU. In theory (from memory) I believe it may well run without that connection, but I'm not surprised you get misfire problems as a result, noise on pin3 produces this problem.
You can connect pin3 of the amplifier to ground directly, while you are at it make pin2 as good a ground as you can make it too, this as standard goes back through the loom to connect to ground remotely which is less than ideal.

 

richm big big thx ) That's what I needed

 

no probs - let us know if it works OK!
I did a lot of investigation in this area and learn't loads about how it works (and indeed how it DOESN'T!!) when we did the zetec turbo project using Marelli management

 

I thinnk it will endup with Subaru ignition anyways, but they are trying to make it run with diostribiutor and all for now. Will let you know when I get the answer from the guys who do it.