Car manufacturers have been installing EGR (Exhaust Gas Recirculation) valves since the 1960s to reduce nitrogen oxide (NOX) emissions. The EGR valve returns a small amount of exhaust gas back into the combustion cycle, using the gas temperature to quickly heat the combustion chamber while preventing it from becoming too hot as the engine warms up. Whether electrical or mechanical, the EGR valve opens and closes to control gas flow. If the valve remains open due to a malfunction, excessive vacuum will cause irregular idling, power peaks or stalls; if the valve, on the other hand, tends to remain closed, it can cause the mixture to detonate and therefore knock in the head, which consequently worsens consumption and reduces the life of the engine. To avoid stalling, power surges, rough idling and knocking, clean your EGR valve.
Steps
Method 1 of 2: To Clean a Mechanical EGR Valve
Step 1. Detach the intake pipe and carefully check for signs of wear (weak spots or cracks), then clean the carbon deposits with a specific spray for carburetors or, if the deposits are compact and hardened, a brush to clean the tubes
Step 2. Unscrew all screws joining the EGR valve to the engine
Check the seal on the valve flange. If it is not worn and has no cracks, you can reuse it.
Step 3. Use a spray to clean the carburetors and a short-haired toothbrush, toothbrush, or pipe cleaner to remove carbon residue from the metal exhaust return pipe and the gas inlet on the valve (usually this is the smaller hole with a spring pin)
Step 4. Clean the passage connecting the valve tubes to the motor (usually on the inlet manifold) when the valve is disassembled
Step 5. Check that the intake diaphragm is free to move, then screw the EGR valve back on to the engine and reconnect the gas recirculation and intake pipes to it
Method 2 of 2: To Clean an Electric EGR Valve
Step 1. Disconnect the cable from the battery negative to prevent voltage being present in the system, so as to avoid accidental short circuits on the components that control the valve
Step 2. Unplug and remove all sensors and electrical connections as well as all hoses pertaining to the valve
Step 3. Unscrew the screws to disassemble the EGR valve and its gasket
Step 4. Check the condition of the pipes and gasket to decide whether to reuse or replace these parts
Step 5. Spray the carburetor cleaner on the valve and pipes, use a suitable brush to remove carbon deposits from the pipes, passages and valve needle
DO NOT spray the carburetor cleaner on electrical plugs and sensors: if these are oxidized or corroded you can use a deoxidizer spray or silicone spray respectively.
Step 6. Screw back the EGR valve with its gasket and bolts, reconnect all pins, sensors and hoses
Step 7. Reconnect the cable to the battery negative
Advice
- Read the maintenance booklet of your car to know the right inspection intervals. As a guideline, the EGR valve should be checked every 20,000-24,000 kilometers. If after cleaning the EGR valve it seems to you that it clogs up again too quickly, have your mechanic do a check; it may be that your engine produces too much carbon residue and needs a thorough check.
- If you can disconnect the EGR valve from all its accessory components (pipes and electrical connections) you can also immerse it completely in the carburetor cleaner instead of spraying it, so as to dissolve all the encrustations and clean it thoroughly inside and out.
- Whether you dip or spray the valve to clean it, peel the gasket off it and keep it dry and clean, as the carburetor cleaner attacks the rubber parts.
