If the air pump fails on an 87 GTA (305 MPFI) would that cause it to idle rough, back fire and die when you give it gas?

 

It can because the oxygen sensor is basically reading wrong. The air pump pumps air into the exhaust before the O2 sensor reads it, therefore if the air pump is not working, the computer is being fed the wrong info.

 

I took the air pump off my MPFI 2.8 and It didn't change any thing.
It might be some thing else.

 

the only thing the air pump does is pump exhaust back into the motor. If it's not pumping exhaust into the engine the o2 sensor see's this an makes the changes. I too do not have the air pump connected.

Isn't your air pump pulley driven?

 

EGR pumps exhaust back into the engine.

The AIR pump is a polution control device used to lower emission levels. When an engine is cold and running rich until it warms up, the emissions are very high. The AIR pump pumps air into the exhaust to mix with the unburnt fuel and lowers the emissions. Once an engine is up to operating temperature the AIR pump is just along for the ride and serves no other purpose.

 

If its back fireing and dieing sometimes then it might be a vacum leak or an intake gasket that needs to be changed. I remember i forgot to put the gasket on between the tb and plenum of my 5.7 tpi car and it did exactly what your car is doing. It might also be the egr. I highly dought its the airpump. But if it is then just take it off.