rotor_veux

iTrader: (3)

Hello, after doing a fair bit of research I have figured out most of this issue but not 100% on Tachometer problems?

Story:
I did a full 1-1 engine swap, aside keeping main power harness though-out.

I had 0 problems before and 0 problems after then POW it's pulling the usual erratic behavior. I have tried swapping a Trailing coil and Cluster. even ideling sometimes It will jump and stay at 4,000rpm, 0, 1-3k and in most cases it will work perfectly fine at start up for up to a minute.

I have even swapped harnesses for the cluster.

Aside from the chance of a previous owner tapping into a certain wire for power: causing draw as changing coils out doesn't help. Knowing they work as we use them in a perfectly running car. I'm not the best with diagrams to figure out which set of wires gets signal to the dash tachometer could I get some help please? Also intrested In other views that could be problem causing.

satch

iTrader: (1)

Yellow/Blue wire at the trailing coil sends the signal to the tachometer. If the coil/igniter is not grounded to the fender properly the coil will not work. If the coil doesn't work then no tach. Secondly, if either the plugs or plug wires are snafued then the tach won't work because the trailing coil won't work. You will find bullet connectors at each of the coils. They are a short lengthed wire not connected to anything and if you jumper the two of them together then the tach should work off of the lead coil. If the tach then works then you know it isn't the tach or the wiring to the tach but something specific to the trailing coil. A car can start, idle and run properly just on the lead coil.

rotor_veux

iTrader: (3)

I've never used the stock tachometer off the leading coil, I will try that.

But I will note that I have an aftermarket Tachometer that works fine just using the leading coil for signal and shows no problems.

I'll guess Ill double back though, most likey just a garbage coating on or around leads or the connectors.

Guess this one is closed, as all the ways of checking where mensioned, up to me to clean and go though all of it.

Thanks for input satch, was easily understood in your post.

rotor_veux

iTrader: (3)

Opening up the Trailing coil< noticed corrosion build up behind T1-T2 covers, WD40 cleaned and added two new grounds one for Harness supplying power to the Trailing coil and the Trailing coil ground.

Not sure which one was the culprit, but cleaned and grounded my way to real time rpm.


Can't really think of a reason why my trailing coils would get corossion but, I assume when freighted over from japan years ago overseas (salt water), showing up now as a problem.