Will a 2004 2.2 liter ecotec chev cobalt engine fit in 2005 cobalt?

Yes, a 2004 2.2L Ecotec engine should fit in a 2005 Chevrolet Cobalt. Both years used the same basic engine and chassis. However, there might be minor differences in wiring harnesses, sensors, or other peripherals. You'll want to ensure that all the necessary components (wiring, sensors, etc.) are transferred correctly from the donor 2004 engine to the 2005 car. It's best to use the engine harness and computer from the 2004 vehicle to avoid potential compatibility issues. A professional mechanic can help you determine if there will be any significant hurdles to overcome.