franky

I was leading toward what billman say above since u recently did an engine swap. Tat small ground wire is most often forgotten since its hidden. It will prevent the car from starting or like u say speedo n temp gauge being very inaccurate. It happened on me so I read somewhere about hooking up a scanner to the ob2 port n my engine fired up.

Its a very quick n simple test. Sometimes we get too excite about the new engine tat we overlook the basic connections but glad to hear u found the problem.