"02 express 2500 EGR problem!

Update from earlier post:
I had a po 443 code occure awhile ago. The book said it was the emmission control purge valve. After consulting Alldatadyi.com and this forum I ordered a new OEM EGR valve and installed it. Unfortunately there is no change. The engine still will not start and stalls badly without holding the throttle on, and engine light comes on, sometimes blinking. The code still comes up as po443 along with po 300. (sometimes a "P" is after the code, does anyone know what that means?) What am I doing wrong? I even made sure I did'nt put the part on backwards.

Update from earlier post:
I had a po 443 code occure awhile ago. The book said it was the emmission control purge valve. After consulting Alldatadyi.com and this forum I ordered a new OEM EGR valve and installed it. Unfortunately there is no change. The engine still will not start and stalls badly without holding the throttle on, and engine light comes on, sometimes blinking. The code still comes up as po443 along with po 300. (sometimes a "P" is after the code, does anyone know what that means?) What am I doing wrong? I even made sure I did'nt put the part on backwards.



The P is OBD11 and engine codes.
You are working on the wrong part.:rofl:
But I do not think a code P0443 will give all of the missfires.
Code P0443 is a plurge solenoid or solenoid circuit code.

For missfires go over you secandary ign.
Plugs wires cap and rotor and camshaft retard setting.
And use good AC-Delco stuff.
How long since a good tune up?
Fuel filter and air filter ever been changed?
How many miles on it and what engine.
Also run a fuel pressure test.

Post back fuel pressure readings.

question: if the fuel pressure is low( meaning a restriction some where??)

-Would that Restriction most likely be at the fuel filter???(with all the lines perfectly fine.)

-How many Kilometers does the dealer recommend you to change it?

-Would this cause stalling after start sometimes? or little rough idle?

Low fuel pressure can be caused by a pluged filter or weak fuel pump or fuel pressure regulater.
Remove fuel filter and see if you can blow threw it with your mouth.
No certain mileage on fuel filters.
One tank of dirty watered down gas can plug a fuel filter.
What is you fuel pressure reading?
Post back and answer questions in post 2.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

To check for a pluged fuel filter and.
Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.