How To Test The EGR Valve (1992-1995 2.2L Beretta, Cavalier, Corsica, Sunfire)

TEST 4: Making Sure The EGR Valve Pintle Is Not Stuck Open

In some cases, the EGR valve pintle remains stuck in a position that allows a constant flow of exhaust gas into the intake manifold.

Generally, the culprit is carbon deposits keeping the pintle from completely closing in its seat and cutting off the flow of exhaust gas.

To find out if the EGR valve's pintle is stuck open, we need to remove the valve and blow compressed air into the valve's exhaust port to see if it comes out of the valve's intake air port.

If the EGR valve is OK (not stuck open), air will not pass into the EGR valve and exit from its intake air port (see image above).

Let's get started:

1. 1

   Remove the EGR valve from its location on the side of the cylinder head once the engine has cool down.

2. 2

   Turn the EGR valve over.

3. 3

   Visually check to see if the valve's pintle is stuck open.

4. 4

   Blow compressed air into the bore (that contains the pintle) and see if this air comes out the outlet.

5. 5

   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 test result. Unfortunately, it tells you that the EGR valve's diaphragm is bad.

You can conclude that the EGR valve is bad and needs replacement if you have:

• Confirmed that the EGR valve IS NOT receiving vacuum when the engine is idling (TEST 1).
• Confirmed that the EGR valve's pintle DOES NOT rise and the engine's idle is unaffected when applying vacuum to the EGR valve (TEST 2).
• Confirmed that air DOES NOT pass thru the valve (this test section).

NOTE: You can re-use the same EGR valve gasket if it isn't damaged. Whether using the same gasket or a new one, you must install the gasket dry. In other words: DO NOT use any sealer (like RTV Silicone) on it.

CASE 2: Air passed from one port to the other. This test result tells you that the EGR valve's pintle is stuck open. Replace the EGR valve.

TEST 5: Checking For Blocked EGR Passages

So far, your tests have confirmed:

• The EGR valve's vacuum hose IS NOT supplying vacuum to the valve when the engine is idling (TEST 1).
• The EGR valve's pintle and diaphragm moved up/down when you applied/released vacuum to the valve, but the engine's idle DID NOT worsen (TEST 2).

It's a common problem for carbon deposits to block the passages that channel the exhaust gas into the intake manifold.

In this test section, we'll perform a very simple test that'll help us confirm whether or not the EGR passages are blocked.

IMPORTANT: If the engine has been running for any length of time and the EGR valve is hot, wait till the engine cools down completely before removing the EGR valve.

Let's get started:

1. 1

   Remove the EGR valve from its place on the engine.
   
   NOTE: Remove any and all parts, nuts, tools, or anything that may fall into the open ports on the EGR valve adapter.

2. 2

   Start the engine and let it idle for no more than 10 seconds.

3. 3

   After no more than 10 seconds, turn the engine off.

4. 4

   You'll see one of two results:
   
   1.) The engine started and ran with a very high idle and/or stalled.
   
   2.) The engine started and ran normally (no high or rough idle).

Let's interpret your test result:

CASE 1: Then engine started and idled normally (no high or rough idle). This test result confirms that the exhaust gas recirculation passages are blocked, preventing exhaust gas from entering the intake manifold.

Your next steps are to remove the EGR adapter block and check it for carbon blockage (obstruction) and possibly even remove the intake manifold to check it for EGR passage blockage.

CASE 2: Then engine started and idled high and/or the engine stalled. This is the correct and expected test result and tells you that the EGR passages ARE NOT blocked.

You can conclude that the EGR valve is bad if you have confirmed:

• The EGR valve's vacuum hose IS NOT supplying vacuum to the valve when the engine is idling (TEST 1).
• The EGR valve's pintle and diaphragm rose when (you applied vacuum to the valve), but the engine's idle DID NOT worsen (TEST 2).

How Can I Tell If I Have A Negative Or Positive Back Pressure EGR Valve?

All vehicles covered by this tutorial come equipped with a negative back pressure EGR valve.

But it's not unusual to find that the EGR valve has been replaced by an aftermarket positive back pressure EGR valve.

If the EGR valve on your vehicle has application numbers stamped on its diaphragm housing (see the image above), you can determine its type.

The numbers stamped on the EGR valve should have a trailing letter N or a letter P. The letter N indicates a negative back pressure EGR valve.

The image above shows an EGR valve stamped with the letter N indicating it's a negative back pressure EGR valve.

An EGR valve stamped with a trailing letter P indicates a positive back pressure EGR valve.

Why is this important? Because only the negative back pressure EGR valves can be bench-tested off of the vehicle with a vacuum pump.

More 2.2L Beretta, Cavalier, Corsica, And Sunfire Diagnostic Tutorials

If this tutorial was helpful, be sure and take a look at all of the 2.2L Beretta, Cavalier, Corsica, And Sunfire diagnostic tutorials in this index:

• GM 2.2L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Thermostat (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire).
• How To Test The Fuel Pump (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire).
• How To Test The TPS (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire).
• How To Test The GM 2.2L Ignition Coil Pack.