Problems With The Rev Counter Using The Twincoil Adapter

[Jamal 2]

Hi everyone!

 

Has anybody used this adapter in the turbo swap?

rev_v_gleges_.pdf

I have got a tacho from an XM(using the ECU-s pin 43 for rev signal) and built this adapter, wired in but its showing too much rpm.

 

Using an oscilloscope to measure 100Hz on the ECUs pin 43(its equal to 3000 rpm) modified the needle on the GTi-s rev counter. But when the engine idled, the counter showed 0. So I twisted the pcb that holds the two little spring to gain more force on the rev counter to get it back to 0.

 

But it was not enough, managed to settle on 950 rpm, realy close to the bottom bumper of the rev counter, but on 3000 rpm(measured) it showed 3500.

 

What is the problem? What did I do wrong?

 

I will try to bulid in the XM-s rev counter, maybe its possible.

[petert 588]

That's just the nature of the beast I'm afraid. You can be 500 out in the midrange and then spot on at 7000. I take it you have a signal generator? If so, just sweep across the rev range and adjust as required. It's a near impossible task to get it right everywhere. I settled on getting 6000 to 7500 correct.

[Jamal 2]

Okay, I will try to calibrate it on high revs.

But the problem is I can not bear this tardiness

 

To build in the XM tacho is so easy if You hasn't build in a boost gauge already under the standard tacho...