Service Engine Light - OBD

[grandprix96]

Hi,



SYMPTOMS:

I own a 1996 Pontiac Grand Prix. Recently the "Service Engine Soon" light has been staying on while driving. I've had several garages check it and they all point to the "EGR" (Exhaust Gas Recirculation) error code as the cause of the light staying on. I did have a cracked exhaust manifold (now repaired), replace the EGR valve (light still on), and two new mufflers (light came back on after reset). The code states "insufficient EGR flow."

Car is well maintained; engine runs good, no misfires according to OBD scan by the garages I've visited. Has 122K miles. No major problems since I have owned it (purchased in 1999 with 41K miles).

QUESTION:

Has anyone else experienced similar symptoms on this type of vehicle, or, on any vehicle? Replies are greatly appreciated. Thanks.

Chuck

[GTP Dad]

Did you clean the passageway to the EGR valve when you replaced it? These get carboned up very easily and with 122K it could be blocked. You can clean this yourself if you are a shadetree mechanic but if not then take it to a shop and have it done.

[grandprix96]

Originally Posted by GTP Dad

Did you clean the passageway to the EGR valve when you replaced it? These get carboned up very easily and with 122K it could be blocked. You can clean this yourself if you are a shadetree mechanic but if not then take it to a shop and have it done.

Thanks for the tip. What is the best way to clean the passageway? How about the hoses to/from the EGR valve? Thanks.

[GTP Dad]

Remove the egr valve and look at the passage in the manifold. If it is blocked you will probably need to remove the manifold to clean it out properly. These new engines have a carbon build up problem due to all the emission control equipment and the fix usually isn't easy. Once you have the manifold off get a can of carb. cleaner and a brush. One used to clean guns works well. Spray the brush and run it through the passageways. This will clean all the carbon out. Then flush the passageway with the carb cleaner by spraying it into the hole. Let the cleaner totally dry before reinstallation. I don't know what size engine you have but you may get by with only removing the phlenum. This is quite easy to do and should take a couple of hours. Save yourself some grief and purchase a Chiltons or Haynes manual. This should be a great help in showing you what to do.

[s_jo4]

change your spark plugs and inspect the plug wires and of course i'll try to decarbonize the intake, but best bet you need new plugs if you have a lot of carbon build up.

[grandprix96]

Thanks for your help. Due to time constraints, I had a local shop check the problem. They did exactly what you had stated and the problem has been resolved. Thanks, again.

P.S. I really should replace the plugs & wires. I've owned the car for almost 5 years and 82K miles and haven't replaced either.

[grandprix96]

Thanks for the suggestion. As I stated in a reply to an earlier reply to my posting, I am WAY overdue for replacing the plugs & wires. The local shop cleaned the port with some good cleaner and reset the engine code. The "Service Engine Soon" light has not come on since. Yesss!

The car is due for tires and brakes; after that I think I'll go for the plugs & wires. I recently also had the following replaced: right/rear exhaust manifold, dual mufflers, rear shocks, right ball joint, EGR valve. Tomorrow I'm putting on new Goodyears and brakes. After that, new plugs & wires when the pocketbook allows. It's handling like a new car but at a fraction of the cost!!