How do I determine how much torque my impact wrench makes?

how old is the battery, test and recharge, if ok make sure is well oiled. May have to have it serviced if it is still low on torque.

The ratchet pawls have seized and a ratchet rebuild kit is needed.

You can not use that model for the torque you require. A larger capacity torque wrench will be needed.

Ingersoll Rand 2705P1 1/2 inch 40-200 ft lb Industrial Duty Impact Wrench
Max Torque 400 Ft-Lb

Pneumatic Impact Wrench, Industrial Duty
Pistol Grip Style
Standard Anvil
Square Drive Size 1/2 In
Torque Range 40-200 Ft-Lb
Max Torque 400 Ft-Lb
Average CFM @ 15 Second Run Time 4.2
CFM @ Full Load 23
Max Bolt Capacity 5/8 In
Free Speed 8500 RPM
Pin Retainer Type
Required Pressure 90 PSI
Air Inlet 1/4 In
Min Hose 3/8 In
Overall Length 6 3/4 In
Weight 2.55 Lbs
Country of Origin: USA
CR 4Z942

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

if you dont use hand tools often you should never trust the torque from impact wrench you should always recheck with tension wrench for correct torque specs
or at least hand tools such as breaker bar, spanner, ratchet
depending on what your doing up and diameter of bolt or studd for what application

Make sure the fitting are tight on the hose and gun. Also make sure that the switch for forward/reverse is solidly in one position, if it is not it will cause what you described.

Most consumer electric impact wrenches are rated in Inch pounds of torque. Divide by 12 to get the foot pounds.

An impact wrench also requires a few special accessories. An air-powered impact wrench runs off of an air compressor with a tank – the air compressor should have at least a 10 gallon tank and be able to generate at least 3hp. Also, an impact wrench requires special sockets that are designed to withstand the high torque applied by the wrench.

impact wrenches are often misused by those who don’t know about their special needs. First of all, it is very important to be careful when tightening a nut or bolt with an impact wrench! Cross threading can occur very easily; a novice may also over-torque a bolt or a nut if they don’t know when to stop. To prevent such problems, always be sure to hand-tighten every nut or bolt before using the impact wrench; if you try to start the nut or bolt with the impact wrench, you won’t be able to feel if the threads are crossed. If the impact wrench is not torque controlled – meaning it will stop when the nut or bolt is tightened to a certain torque – you will need to go slowly, and periodically check the torque value of the nut or bolt to make sure you haven’t tightened it too far.

An air-powered impact wrench runs off of an air compressor with a tank – the air compressor should have at least a 10 gallon tank and be able to generate at least 3hp. Also, an impact wrench requires special sockets that are designed to withstand the high torque applied by the wrench.