Ok here's my question.....My friend has swapped a 2000 si engine into his 96 dx ek.... the wiring harness wasn't cut and the factory si ecu came with it. So shouldn't he be able to just swap out the dx ecu for the si's and use the si's wiring harness and be done with it? Im confused because now the tach doesn't work and neither does vtec.... or should he just use his factory dx harness and ecu and wire up vtec? someone pls. explain

 

And by the way...no vtec...cel is on...and idle bouncing....

any ideas on what we should be checking?