Dan Ferrell writes on auto maintenance and repair on his own account. It has certifications in automation and control technology.
Why You Should Know How to Test an EGR Valve
Learning how to test an EGR valve will save you time, money, and some headaches. After miles of service, the Exhaust Gas Recirculation (EGR) system, especially the EGR valve, will cause engine performance problems due to carbon build-up, mechanical component problems, or vacuum hose leaks.
Depending on the particular problem, you will notice symptoms such as rough idle, engine noises or knocks, an increase in emissions, low fuel consumption, difficult starting, and even stalling. However, without a bit of troubleshooting, these same symptoms will mislead you into replacing an EGR valve, solenoid, or missing a simple solution to your problem.
Here, we take a look at a simple procedure for troubleshooting a possible faulty EGR valve and some tips for performing a system cleanup, if necessary. In any case, I recommend that you purchase the vehicle repair manual for your particular make and model, if you don’t already have one. The manual will help you as a reference, either now or later, to identify the exact type and components you have in your EGR system; help you identify passages to clean the system, including the valve itself; and the correct steps if you need to replace the EGR valve. Not to mention all the help you’ll get in future vehicle maintenance and repairs.
You can get fairly inexpensive aftermarket repair manuals at most auto parts stores or online. Or, if you don’t want to buy the manual now, look for a copy of the manual in the reference section of your local public library.
And one more thing. Here, we will deal with the vacuum controlled EGR valves found on older vehicle models and some newer models that use hybrid (vacuum-electronic) controls. However, newer vehicle models come with electronically controlled valves (there are currently about six different types of EGR valve control setups, and some late model cars have ditched the EGR valve entirely). Still, you can follow this guide along with the procedure outlined in your vehicle’s manual to test your EGR valve, if necessary.
To apply one of the tests to the EGR valve, you will need a vacuum pump, which you can borrow and rent from a local auto parts store if you don’t have one. Other than that, you will only need to use a few common tools if you need to clean carbon build-up from the EGR system passages.
However, before doing the test, let’s take a look at the purpose of the EGR system and what the EGR valve does, to better understand the EGR valve test procedure.
What does the EGR system do?
Your vehicle’s EGR system uses the EGR valve to introduce measured amounts of exhaust gases into the combustion chambers. These gases lower combustion temperatures. And lower combustion temperatures mean less emission of harmful NOx (nitrogen oxides) gases.
However, the exhaust gases should not flow continuously into the cylinders. Once the engine has reached operating temperature, the gases gradually begin to flow as the engine speed increases. When this flow pattern fails, you start to notice a decrease in engine performance. For example, this will happen if the EGR valve does not close fully when the engine is idle, or does not open when the engine speed increases.
Unfortunately, sooner or later problems will occur in the EGR system and valve. Over time, the tiny carbon particles contained in the exhaust gases begin to adhere and accumulate along the intake and EGR system passages, clogging the pipes, exhaust channels, and the EGR valve itself. Eventually this will also affect the valve plunger mechanism, causing it to stick to open or close. On top of that, EGR parts and components wear out and stop working properly.
That’s when troubleshooting becomes necessary. You need to confirm if the EGR valve has failed or if the carbon deposits have started to alter the …