TEST 2: EGR Valve Pintle Stuck Open
Over time and thousands of miles, the engine will produce carbon -which will usually end up coating the piston crowns.
Eventually, this same carbon will cause the EGR valve's pintle to become covered in it and keep it from closing against its seat completely.
When this happens, a continuous amount of exhaust gas is recirculated into the intake manifold affecting idle quality, etc.
So, the next step is to remove the EGR valve from the intake manifold and check by blowing air across it.
IMPORTANT: Let your pickup's engine cool down completely before attempting this test since you'll need to remove the EGR valve and the valve gets and stays hot!
These are the test steps:
Remove the EGR valve from its location on the intake manifold once the engine has cool down.
Turn the EGR valve over and visually check to see if the pintle is stuck open.
Blow compressed air into the bore (that contains the pintle) and see if this air comes out the outlet.
Air should no pass thru' to the other side.
Let's take a look at what your test results mean:
CASE 1: Air did not pass thru'. This is the correct and expected test result and tells you that the EGR valve is NOT stuck open.
If your pickup (SUV) is experiencing a rough idle problem, you've eliminated the EGR valve as the cause behind it.
NOTE: You can re-use the same EGR valve gasket if it isn't damaged. Whether you're using the same gasket or a new one it's important that you install the gasket dry. In other words: DO NOT use any type of sealer (like RTV Silicone) on it.
CASE 2: Air passed from one port to the other. This is a problem and tells you that the EGR valve's pintle is stuck open.
You may be asking yourself, ‘Can it be cleaned?’, In my experience it usually can't but you should still try and clean it with carburetor cleaner spray. If the pintle doesn't get unstuck you'll need to buy another.
More GM 4.3L, 5.0L, 5.7L Tutorials
You can find a complete list of tutorial in this index: Index 4.3L, 5.0L, 5.7L Index Of Articles.
Here's a sample of the tutorials you'll find in the index:
- How To Test The Blower Resistor (1988-1993 Pickups).
- How To Test The Blower Motor (GM 4.3L, 5.0L, 5.7L).
- How Can I Tell If My 4L60-E Transmission Is Bad?
- Shift Solenoid A And B Tests (GM 4.3L, 5.0L, 5.7L).
- How To Test The Engine Compression (GM 4.3L, 5.0L, 5.7L).
- How To Test The GM Distributor Mounted Ignition Module (at: easyautodiagnostics.com).
If this info saved the day, buy me a beer!