LOTUS ESPRIT S4 TURBO Link g4 FURY X ECU / tachometer not working..

[urr]

Hello everyone ,

We are now working on a Lotus esprit s4 turbo, and our vehicle is equipped with a Link g4 FuryX ecu. We linked the tachometer to aux 9 on our  ecu, but it does not function at all. What could be the cause of this, and do you have any diagram ? Have you ever encountered a situation like this before? It would be wonderful if you could possibly share your solution.Thank you for your all helps

[koracing]

Do you have any factory wiring diagrams for the original tach driving circuit?  It could be the tach is expecting a different signal than what the Link ecu puts out - which may mean it needs an amplifier of some sort put in between the ecu and the tach, but without information on the original setup or how the tach was driven from the factory - it would just be guessing.

Also - your wideband isn't likely to live a long life that close to the turbo exit.

[Adamw]

A quick google suggests there are potentially 2 different types of tachos used in these - neither will work connected directly to the ecu but both will require a different technique to make them work. 

The 2 different types are often referred to as voltage sense and current sense.  The voltage sense type originally would have connected to the negative post on the coil, it uses the ~100V kick out of the coil primary every time there is a spark to signal it.   The current sense type is connected to the positive post on the coil and is actually the power supply to the coil - all power supplied to the coil goes through the tacho, so the tacho has a small transformer inside that picks up the current pulses.  

If you know what side of the coil the tacho was originally connected to that will help, or if you can find a wiring diagram that you are confident matches your car then we can base the advice off that.  

Another bit of info that would be useful is what you are using for an ignition system now - distributor or cop or wasted spark, coil((s), ignitors etc.