I recently upgraded my cars exhaust system and removed the catalytic converters. But after doing so the car won't start. Ran a diagnostic test but nothing showed to be faulty. Does anyone know what could be the problem?

 

There's so much information missing here that no one could possibly give you an accurate diagnostic.

For example:

1. Is the battery reconnected (presume it is else no OBD test) so, is it even cranking?

2. Did you plug the O2 sensor(s) back in? Check condition of same after pulling them off?

3. What did you replace the cats with, test pipes? HFCs?

4. Anti-foul caps in place?

5. Automatic or 6MT?

Devil is in the details.

 

I would suggest having your car towed to a mechanic before you mess up something else.

 

Have you tried turning the key?

 

I've had this problem before. I installed nitrous oxide producing 250 hp and "hit the switch" right after popping the clutch while rolling downhill to get it started. Cleared it right up but then I ran into a tree.

 

it's a 2006 6 speed manual
battery is new and connected
car cranks but does not start.
cats are replaced with test pipes
and o2 censors are back place.
I however do not know the condition of o2 censors as I did not do the work myself.
would a OBD test pick up a faulty censor? And would the car fail to start if that censors are indeed faulty?

 

 

The crankshaft position sensor could have been unplugged or damaged... it's right in the vicinity on the bottom of the engine when messing with cats/test pipes.

 

The engine could be flooded from starting it and moving it quickly and shutting it off before the engine warmed up.