Why does the engine run better when you unplug egr solenoid on your 1991 gmc ck1500 5.7 tbi and is this harmful?

The engine may run better when the EGR solenoid is unplugged because the EGR system is not functioning properly. The EGR system recirculates exhaust gas back into the engine to reduce emissions. When the EGR system is not working properly, the engine can run richer and produce more power. However, this can also lead to increased emissions and decreased fuel economy.

Unplugging the EGR solenoid is not a permanent solution to a malfunctioning EGR system. The EGR system should be repaired or replaced as soon as possible.

Here are some of the symptoms of a malfunctioning EGR system:

* Engine knocking or pinging

* Decreased fuel economy

* Increased emissions

* Check engine light on

If you are experiencing any of these symptoms, you should have your vehicle inspected by a qualified mechanic.