96 3.1 check engine shows 0401 code

[foneman611]

I am trying to get my car through emissions inspection.I started out with 2 codes 0303 and 0401.The 0303 is a misfire code. I replaced plugs and wires and replaced all 6 injectors and car runs great got rid of 0303 code but still has 0401 code which is an egr code. Tried to get a waiver due to money spent but must pass a curb idle test with sensor directly into tailpipe.That failed for too many hydrocarbons.The egr valve was replaced at last inspection and was passed through but check engine light came back on about a week later(this was 2 years ago). Didnt bother checking because car ran great and had passed inspection. What else can cause this 0401 code besides everything that was allready replaced. Could the egr valve have been faulty from the get go? Is this 0401 code causing the ecm to make the car run too rich which I think would cause the hydrocarbons in the exhaust?

[richtazz]

The PCM uses map sensor vacuum to determine EGR flow efficiency, so check the vacuum hose to the MAP sensor for cracks/splits, holes, etc... If that checks out, your next thing to check is the tube that runs from the rear exhaust manifold to the EGR and the EGR itself for carbon deposits.

[foneman611]

Thanks, I will check these out. Will a bad MAP sensor also cause this same problem?

[richtazz]

No, a bad map sensor would trip a MAP sensor code as well.

[foneman611]

I have another thread going which you have also replied to concerning misfires I was getting. If there is a slight gasket leak would this cause the 0401 code to kick in and cause the excess hydrocarbons in the exhaust?

[richtazz]

It could, as the intake leak could be causing a vacuum leak, which would give false signals to the sensors and PCM. The mis-fires are most likely being caused by coolant getting into the combustion chamber from the leaking intake gasket.