Hi !
Just a question : is the EGR of a 1991 305 Firebird TBI normally closed or normally open ?
Regs
P.
Just a question : is the EGR of a 1991 305 Firebird TBI normally closed or normally open ?
Regs
P.
ALL EGR valves are normally closed. EGR at idle makes the idle rough, or even stalls the engine.
Therefore, EGR is only activated at light or medium load, never at heavy throttle; and always at "fast idle" speed or above. Generally, there's engine-temperature lockouts as well--the engine must be warmer than a certain temperature or the EGR is disabled.
The question is less about normally open vs. normally closed, and more about whether exhaust backpressure is also a control mechanism: Some valves don't sense exhaust backpressure. Some react to positive backpressure, some react to negative backpressure. A "P" or an "N" after the part number stamped into the valve is a method of identifying which sort of valve you have.
Therefore, EGR is only activated at light or medium load, never at heavy throttle; and always at "fast idle" speed or above. Generally, there's engine-temperature lockouts as well--the engine must be warmer than a certain temperature or the EGR is disabled.
The question is less about normally open vs. normally closed, and more about whether exhaust backpressure is also a control mechanism: Some valves don't sense exhaust backpressure. Some react to positive backpressure, some react to negative backpressure. A "P" or an "N" after the part number stamped into the valve is a method of identifying which sort of valve you have.
Thx a lot !
P.
P.