How To Test The Linear EGR Valve (1996-1998 2.2L Beretta, Cavalier, Corsica, Sunfire)

TEST 8: Checking For Carbon Build Up

As the engine ages and accumulates thousands of miles, its combustion process produces and releases soot into the exhaust.

This black soot will collect in the EGR valve system passages and harden into a carbon buildup.

Eventually, this carbon buildup will cause the EGR valve's pintle to become stuck 'open' or 'closed'.

This buildup of carbon particles will also clog the intake manifold EGR passages. It doesn't happen overnight, but it will.

So your next step is to remove the EGR valve and inspect for carbon buildup blocking the pintle and/or clogging its two orifices (ports).

You'll also check the EGR valve adapter block's orifices for carbon buildup and blockage.

Let's begin:

1. 1

   Remove the EGR valve from its place on the engine.

2. 2

   Check that the EGR valve pintle is not held open carbon build up.

3. 3

   Check the orifices in the EGR valve adapter for carbon build up and carbon blockage.

Let's interpret your test results:

CASE 1: The EGR pintle and EGR adapter block orifices ARE NOT blocked with carbon. This is the correct test result.

All of the tests you've performed up to this point have not found any problems with the EGR valve. I suggest one last test. Go to: TEST 9: Checking For Clogged EGR Passages In The Intake Manifold.

CASE 2: Both the EGR pintle and EGR base orifices are blocked with carbon. Your next step is to remove the carbon deposits.

Once the carbon has been removed, verify the EGR pintle can completely close on its seat.

Re-install the EGR valve, clear the EGR valve fault codes (that were lighting up the check engine light) and road test the vehicle to see if the problem is solved.

CASE 3: Only the EGR pintle was blocked with pieces of carbon from fully closing on its seat. This condition allows exhaust gas to enter the intake manifold at all times, causing a rough idle and/or engine stall problem.

Remove the carbon blocking the EGR pintle. Re-install the EGR valve, clear the EGR valve fault codes (that were lighting up the check engine light), and road test the vehicle to see if the problem is solved.

CASE 4: Only the EGR Base orifices were blocked/closed off with carbon. This blockage will not allow the flow of exhaust gas into the intake manifold.

Your next step is to clean/remove the carbon. Re-install the EGR valve, clear the EGR valve fault codes (that were lighting up the check engine light [CEL]), and road test the vehicle to see if the problem is solved.

TEST 9: Checking For Clogged EGR Passages In The Intake Manifold

So far, the EGR valve has passed all of the tests in this tutorial; however an EGR system diagnostic trouble code still lights up the check engine light.

There's a good chance that the EGR flow passages (which are not visible) in the intake manifold are clogged (blocked) with carbon buildup.

You can check for this condition with a specific test: start the engine with the EGR valve removed from its place (on the EGR adapter block) and see how the engine idles.

Let's start:

1. 1

   Remove the EGR valve from its place on the engine.

2. 2

   Start the engine.

3. 3

   You'll notice one of two things:
   
   1.) The engine will start and run smoothly (as if the EGR valve where still there in its place).
   
   2.) The engine will start and idle extremely high and/or stall immediately.

4. 4

   If the engine starts and idles very very high, have your helper immediately turn off the engine.

Let's interpret your test results:

CASE 1: The engine started and idled smooth. Then this confirms beyond a shadow of a doubt the EGR passages are clogged inside the intake manifold.

You'll need to remove the intake manifold to remove this carbon build up blocking the EGR passages.

CASE 2: The engine started and idled very high and/or stalled. This confirms that the EGR passages inside the plenum ARE NOT clogged.

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

You can find a complete list of 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.