334 code. Please help

What voltage does your EGR position sensor baseline at (KOEO)? If above 0.60V, you have an issue.

Put a DMM on the signal wire (should be brown/lt green) to the EGR position sensor. Ground the other meter lead. Turn the key on and note the reading. It should be 0.01-0.50 V.

If you were goin to do that, I would have gotten an O/R pipe instead. The larger diameter would have been nice for your motor anyhow. What will you do next year for emissions?

You did clear the codes after retrieving them last, right?

You would have to do some cutting/grinding on either the EGR valve or the position sensor to reduce the baseline reading. This sounds like it would be a little beyond the scope of what you want to do. The kicker is that new parts might give the same reading.

Did you ensure that while idling, you do not have vacuum in the vac line to the EGR? If not, do this. If needed or unsure, disconnect the vac line to the EGR and rerun codes (after you clear the old ones). IF there's vac in that line while idling, it can generate the code.

glowing?

i have had a older gm with a glowing cat problem,,,it ended up being too much fuel...and ive seen once a muffler put on backwards cause a manifold to glow,,,is an egr valve a cause for a cat to glow?

Ok, to clear the KAM you have to disconnect the battery and create a draw (turn on your headlights, for instance). This will deplete the capacitors much faster than their normal half-life. I do this and let it sit for a couple minutes.

You have found an issue however. At idle, the EGR's vacuum line should have NO vacuum in it. 2.5" hg might not be enough to really trash the idle, but you should be able to notice it. It should also cause off-idle surging.

If you disconnect the vac line to the EGR and plug the line, does it still surge? If you go for a test drive, Drive it easy if you do this because you might get detonation (depending upon if the EEC has shut off the EGR function at that time).

Alternatively, trace the vac line and be sure it goes to the EVR (in the passenger fender well. YOu remove the wheel and fender liner to access it). Your EVR might have a leak, causing manifold vac to bleed across the ports.

Sorry for your troubles man, makes me so glad I live in a place where I can chunk that crap in the nearest lake!

You didn't mention what kind of transmission you have. I had a 94 GT with an AODE a long time ago and it is what caused my surging/popping problem.

Resistance tests are generally done with the connector disconnected (applying power to a circuit undergoing a resistance test skews the results).

It should be real apparent real quick if that little niblet is leaking when it should not be.

Good luck.

Disconnect the electrical connector and see if anything changes. If not, it's a hard part issue (not electrical).

If you have a vacuum pump, disconnect the feed vac line to the regulator and connect the pump to the inlet side of the regulator. With the engine off, apply vac and listen for hissing.

You could also have a crack in a hose or a cracked regulator. Look for the leak like you would a conventional vac leak.