NefMoto

A friend wishes to remove from his car the n2mb wot box in order to install to his car the NLS & LC function.
We remove it but we ve faced a problem.
Wot box was installed by cutting the two ground ignition coils (black / purple color code) cables which are feeding ignition coil fuses at port 1. After removing it, those cables must be connected together. To be more specific this ground connection is one cable which is splitted to 2 and after to 4 in order to feed each ignition coil separately.
Wot box uses one cable to manage the ground signal. So we dont connect those two cables we cut, one by one, but we use one ,a bit bigger copper wire, think it is 2.25 thick,  and connect them together. First we join the cables together and check that are joined ok with a multimeter, after we solder them and cover them with shrink heated tube.
Car is starting fine and under 4000rpm works as before. After 4000rpms on full throttle is misfiring very badly and non go.

What could be wrong?
Shall we desolder them and use 1.5 thick cable and connect each cable separately?

Any suggestions are welcome  :)

Interesting.

A friend's car did similar thing WITH wotbox installed, happend sometimes only! we figured a bad solderjob(someone else did it) we are removing it at some point when we get to the car again(in storage)

I see.
Well the solder job was made with caution and don't think that there is the problem.

Well the problem looks to be a malfunctioned ignition coil which after 1-2km deliver its spirit and now the car works 3cylinder.

dont forget that WOTbox type stuff is generally hard on drivetrain and ignition