EGR valve not closing all the way [Archive] - Forum


View Full Version : EGR valve not closing all the way

02-16-2010, 01:36 PM
So I had probelms with the EGR and the code said it wasn't closing to the correct posisition. I changed the valve thinkning it was the cellinoid going bad. I cleared the code with a diagnostic computer and drove it for a while and it was fine. I had the computer hooked on to it later just to see how low the air intake tempature would go because of the ram air (It went to 32 degrees and the air was 32 degrees) and when I steped on it all the way the code came back. I got looking and when the PCM commanded the EGR below 12% it would only go as low as 12%. Anything above 12% it would open to what is was commanded to. I then unhooked the wiring harness on the EGR valve and drove it arround like that for a while (and shut it off and restarted it about 6 times) and it didn't throw any codes. The EGR valve is new and the wiring harness contact points were perfect. I'm going to assume that the valve does actually close all the way because it is brand new. Does anybody know what might be causing the valve to stay open?

02-16-2010, 02:05 PM
check the exhaust pipe. could very well be clogged

02-16-2010, 02:06 PM
When you changed the valve did you check to make sure there wasn't any carbon built up in the riser tube or the intake manifold?

02-16-2010, 03:20 PM
The codes he has been getting are for the pintle position, so even if something was clogged it shouldn't set off that code. The computer just checks the pintle position compared to commanded position, flow should have nothing to do with it.

If you replaced the valve and it's still a problem, then it has to be something else electrical. Either the connector at the EGR or at the PCM, a break or short in the wiring harness somewhere in between, or a problem with the PCM itself. There really isn't anything else to the system.

02-16-2010, 05:33 PM
Just to note, a clogged catalytic converter could cause a pintle position code to set.

Its not very common on N-bodies for the EGR to be affected by a restricted cat, but it can happen. Clogged cats on N-cars are quite common, however.

02-16-2010, 06:08 PM
That could be it. I know when the car is running it only returns to 12%, but if the car is on, but not running it returns all the way to 0%. I believe you that it can happen, but (for the sake of knowlage) why would that affect it?

02-16-2010, 06:44 PM
Good point Scott, I didn't even think of that.

Mike, the EGR flow works on a pressure differential... not just vacuum in the manifold but also back pressure in the exhaust affects it too. If the cat is clogged it's going to make the pressure in the exhaust rise and could be forcing the EGR valve open part way trying to relieve the pressure. ;)

02-16-2010, 06:50 PM
That makes sense. Theres probally not an easy way to check the cat to see if its getting clogged without tearing the exhaust off is there?

02-16-2010, 06:52 PM
Not really no. Most people don't know they are getting clogged until they experience a dramatic loss of power and/or bad fuel mileage, and they usually start getting codes for misfires or O2 sensor malfunctions.

02-16-2010, 07:02 PM
I was thinkning about taking it off and punching the guts out of it anyway to get more exhaust flow. Would that mess with the O2 sensor and throw a code or hurt the car in any other way?

02-16-2010, 07:08 PM
Hook up a vacuum gauge and bump the throttle a few times. If you have a super slow return to full vacuum its a clogged exhaust. If the needle snaps back its not the exhaust.

04-06-2010, 09:37 PM
I had the same problem with my EGR valve. all i did was remove my cat and now my car sounds amazing and it runs perfect.

04-07-2010, 04:55 PM
I had the same problem with my EGR valve. all i did was remove my cat and now my car sounds amazing and it runs perfect.

It probably was clogged and the back pressure was keeping the EGR partially open. Removing it removed the back pressure, but know it probably sounds like ass and smells bad and is kicking out a bunch of pollutants. Should have just replaced the cat with a high flow.

04-07-2010, 08:20 PM
i got the same issue...looks like i might be taking a cat off this weekend.

04-08-2010, 11:38 AM
Mine was fine after a couple days of running it, so wait a couple days before doing anything. My GUESS (and i'm sure somebody will tell me I'm wrong) is that the car needed a couple trips to realise the EGR valve was working right again even after I cleared the code.