Carnot Cycle: Reversibility Under Constant External Pressure

[asap9993]

An ideal, monatomic gas is going through a 4 step Carnot cycle. Step 1 is an adiabatic expansion. Step 2 is an isothermal expansion. Step 3 is an adiabatic compression. Step 4 is an isothermal compression. The whole cycle is reversible. My question is how would the cycle change if step 1 is done against constant external pressure. Would the work be different?

 

[ehild]

What would be the endpoint of that isobaric expansion? ehild