After installing my aftermarket tachometer on my 99 2wd 2.4L 2RZ-FE, my idle became rough. I took the green wire(rpm read wire) off of the black/yellow wire off of the front coil pack and the idle becomes normal again. Anyone know why adding the green wire from the tach to the wire for the rpm signal on the front coil pack causes rough idle? Anything I can do to fix it? Thanks in advance!

 

uh--maybe that tachometer sucks and has a low impedance, or lower than the impedance of your coil packs. maybe try a 1k resistor in line with that tach wire to increase the resistance.
if that doesnt work--get another tach, or the whole guage cluster from a recycler with the tach in it already! then it will work for sure.


T