5 speed swap gone bad
 

I'll keep it short, I did a transmission swap a month ago used a lot of mix and match parts from junk yard and friends but it won't start now, it cranks backfires then stops cranking then starts cranking again. Is it possible that I might have moved the timing taking out the old transmission, do I have to ground anything on the wiring harness (automatic harness), or could I have just installed the clutch and flywheel wrong. Please help

Unless you touched the timing for some reason, the timing isn't the problem. The other things could possibly be a problem.

found the problem.

but really - check your crank and/or cam sensor and the wiring going to them.

^ Like 18psi said, check your wiring. That is honestly the only thing that could have really changed.

Yeah I've narrowed it down to the ignition im not not getting a spark, ive changed out the cam sensor and ignition coil to used ones I had around. The only thing I can think it can be is the ecu or I messed up the wiring taking the auto trans or I need to hook up some other cable.

Did you change the ECU? I thought the auto ECU had some funky injector/cam stuff.

yeah, m.net says it'll only start in neutral. Try that?

There's also this bit about the ignition:

"Also, there’s a 3-piece mechanical switch built into the ignition on the A/T car. This switch is activated by a cable that goes behind the dash that extends when the gear selector is shifted into Park. The basic purpose of this mechanism is to keep the key from starting or turning off the car when not in Park. I first thought I was going to need a locksmith to swap lock cylinders between my manual ignition switch and automatic, but it turns out that it’s a pretty easy task to just move over the three pieces that make up the switch. Looking at the ignition switch from the top, there’s a silver panel held in place by one screw. On the automatic ignition, this panel covers a brass slider, a spring, and a silver ‘wedge.’ Once the panel is removed from both ignition switches, these pieces can be transferred in about five minutes."

Read up:

http://www.miata.net/garage/auto_2_5_speed.html

Yeah I spliced the neutral safety switch so it only cranks in neutral. Thanks everyone for the ideas I appreciate it