I am narrowing down why I have a slightly rough idle. I changed plugs,wires,checked for vacuum leaks and corrected them but still a rough idle. About 6 months ago I got a pending error code P0406: Linear EGR Pintle position Error. Cleared it and I haven't seen it since. I am thinking that the EGR value is stuck open all the time. Would the PCM pick this up if it is indeed stuck open?

I had a rough idle a few weeks ago, it was a cracked EGR tube



If this is the case, let me know and I'll get you a link to buy a new one. Cost me about $28 shipped. Replaced and had no more problems. I was throwing codes for lean, rich, missfire, and a pressure control solinoid. All codes went away.

Where is this tube? I haven't seen something like that.

You don't have that tube. You have an L36, which is EGR-fed through the bottom of the UIM. You can see it with the TB off.

Make sure you're not suffering from the proverbial L36 UIM erosion. All L36'* will, and it will cost some the entire motor.

I know mine was replaced sometime after 6-03 which is the date on the Delphi UIM.

Well, Will said you dont have that tube, saves me the trouble of explaining it. That was easy. Will has more information then I do.

It'll happen again. The clock is ticking. It should be a Dorman or APN. We've seen 02 and 03 manifolds fail. I've got one here that did.

This could very well be your problem. Are you losing coolant?



Correction. Series 2'* do have the LOWER tube to the manifold. Not the upper tube the Series 1 has. Check that tube between the rear exhaust manifold and the LIM. The Series 1 has a tube entering the front of the motor up high. Threw me for a minute.

A leak between the valve and the LIM will cause a lean condition and poor idle. But not between the valve and the exhaust manifold.

I'l check that tube.

Not losing coolant and oil is clean as well as oil cap. I check this weekly.

On to my original question, would the PCM recognize a stuck open EGR value?

Yes, the PCM will see a stuck valve.

Here is a picture of a (95) L36 EGR setup. The corrugated stainless steel pipes that carry exhaust gas from the exhaust manifold to the EGR valve and from the EGR valve to the lower intake manifold are shown below. The tubes can become brittle over time and crack. Inspect these carefully as the cracks can be difficult to see. A flashlight and an inspection mirror will help. Or, just undo the fasteners, pull the tubes and inspect them off the car.