Here's why:
* Increased Emissions: The EGR valve is a crucial part of the emission control system. Blocking it will dramatically increase the levels of NOx (nitrogen oxides) in your exhaust, leading to potentially significant pollution and possible failure of emissions testing. This could result in fines in areas with stringent emission regulations.
* Engine Damage: While some older engines might tolerate a blocked EGR valve for a while, the increased combustion temperatures from the lack of EGR can lead to:
* Pre-ignition: Fuel igniting before the spark plug fires, causing knocking and potentially damaging pistons, connecting rods, or even the engine block.
* Increased wear and tear: Higher temperatures put more stress on engine components, leading to faster wear.
* Catalyst damage: The catalytic converter is designed to handle a specific exhaust composition. The higher NOx levels from a blocked EGR can damage or destroy the catalytic converter, leading to a very expensive repair.
* Computer Issues: Many vehicles with EGR systems have computer controls that monitor its operation. Blocking the EGR valve will likely trigger a check engine light and possibly cause the engine computer to enter a limp mode, limiting performance.
In short: While some people do block EGR valves, it's generally a risky modification that can lead to significant engine damage and environmental problems. If you're having issues with your EGR valve, it's far safer and more advisable to have it repaired or replaced by a qualified mechanic. Blocking it is a temporary fix at best and a potentially expensive and damaging workaround at worst.
