My 2001vw passat some times won't start unless i use starting fluid.I have changed air filter and spark plugs. When i hook it up no codes come up

Improper fuel/air mixture, possibly plugged up air filter?
You have 2 out of 3 of the needed components for that motor to run, and assuming your timing is correct and you have compression, it could be an air intake issue.

Something intermittent is wrong with your fuel delivery system - fuel pump, fuel filter, fuel pressure regulator, check valve.. If it always starts when you use starting fluid that eliminates spark/igniter issues. Check all electrical connections in fuel delivery components.

If the ecm is touchy it might not be sending the signal for the injectors to shoot gas into cylinders.

But I think you have a bad connection somewhere along the line.
BTW, great car - have one also. But my dealer sucks.

if it only starts when you add starting fluid then you have a fuel problem. the filter could be plugged the fuel pump may need to be replaced you may not have power or ground to run the fuel pump, you may have a bad fuel pump relay. the starting fluid replaces the fuel that the engine is not getting

run the fault codes . Have a pressure test done on the fuel manifold

PLEASE LIST YOUR QUESTION ONLY ONCE. (IT'S ANNOYING TO FIND THE SAME QUESTION POSTED OVER AND OVER AGAIN.)

If it turns, then the battery is OK. Either spark plugs are not firing in proper order (wrong firing order), no power to spark plugs, or no fuel because of fuel restrictions (dirty fuel filter). Inspect the air filter to ascertain its not clogged air. If you smell gas, then you saturated the spark plugs, which is why it refuses to run.
Let it sit for half hour to let spark plugs dry. Inspect to ascertain its not dirty spark plugs, which will also prevent engine from running. After ascertaining its proper firing order, spark plugs are clean, and there's power to distributor cap, ascertain there's fuel in fuel lines by squirting half second (short squirt) of starting fluid into air filter. Close the air filter housing to trap flammable starting fluid gas. Turn engine without giving throttle. Let starting fluid be ignited by spark plugs. If it won't start, then spark plugs are not firing to ignite starting fluid gas. If it starts briefly, but won't run when you give throttle, but catches when a 2nd person squirts more starting fluid into air filter just before engine stalls, then its a fuel restriction issue or no fuel in fuel lines.

The next time this happens have a can of spray starting fluid handy (available from any hardware or auto parts store), spray it into the air intake of the engine if it starts you most likely have a sticking in tank electric fuel pump problem.

Thanks for choosing FixYa and welcome. For a tune up, you would need to change spark plugs, coils, distributor cap, coil pack, and wires. You would change the air filter and the fuel filter also. Change your pcv valve as well. You can also change all your fluids and filters, such as oil, coolant fluid, and transmission fluid.

YOU PROBABLY HAVE BAD SPARK PLUGS AND WIRES.YOU NEED TO CLEAN FUEL INJECTORS AND CHANGE FUEL FILTER.THIS LITTLE TUNE UP SHOULD HELP.ANY TIME YOU SPRAY ETHER DOWN AIR INTAKE TO GET ENGINE STARTED YOUR ENGINE NOT GETTING ENOUGH FUEL OR SPARK TO COLD START.YOU NEED RICH FUEL MIXTURE ON COLD ENGINE START UP.AS ENGINE WARMS UP FUEL MIXTURE HAS TO BE LEAN.

CHANGE SPARKPLUGS/ OIL/ AIRFILTER/ OILFILTER/ CHECK DRIVE BELTS FOR WEAR / CHECK MILEGE USE ON TIMING BELT AND REPLACE BELTS IF WORE.