Mr. Malcontent

Finished the valley pan gasket yesterday. While I was there I cahnged the oil retention valves also and it there is a huge difference. Now it doesn't sound like diesel.

When I had the EGR valve disconnect and the IM out, the valve was able to move around quite a bit. Is it supposed to have a lot of movement or not?

AudiMick

<center><img src="http://pictureposter.audiworld.com/37725/egr_001.jpg"></center><p>The EGR is the lower one and I don't remember it moving very much. The changeover valve above it (black in the picture) can move some.

4kqlifer

Did you clean out the egr passage?

Mr. Malcontent

EGR valve, it moved about 6" in any direction after unbolted.

Mr. Malcontent

I cleaned the IM and TB. So I removed the fuel line and injectors to get into the IM. This probably adds about 2-3 hours to the job.

4kqlifer

And the egr? I'm asking because I just failed emissions and need to do this this next weekend as well as the VP gasket. It smells bad after driving for awhile. I can't wait till that's gone. Also because I just bought it, I can't license it till I get the emmisions passed (Washington is strict). I gotta say that I do love the steering feel in these cars (97 a6q). Makes me think that the s cars of years prior would be pretty fun. So how does it run now?

VAP

<center><img src="http://pictureposter.audiworld.com/711/egrfunction.jpg"></center><p>
In this pic on a new EGR valve you can see the diagram of how stuff works.

Diagram details;

Yellow: Silicon rubber diaphram
Blue: Actuator rod (plunger)
Orange: Valve seat (shown in closed position)
Red: travel distance

As the actuator rod moves up and off its seat exhaust gases are released out of the intake manifold flange cast in the side of the EGR valve body. When actuator rod is closed down on its seat all exhaust is evacuated out the exhaust manifold and doesnt go into the EGR valve.

This diagram will also show the "EGR mod" is folly as there is simply no exhaust gases in the top of the EGR which vents to the intake tract upstream of the throttle body butterflies. Its a totally different/separate chamber than the underside which does receive VERY small amounts of exhaust gas blow-by past the stem seat but is vented to atmosphere via the cut-outs in the lower half of diaphram housing. While you can eliminate (but not seal or "cap-off") the upper vent stem and corresponding location on the plenum, exhaust gases will still find its way into the IM EGR passage and those exhaust gas temp spikes within the IM is what prevents the venerable "non-sufficient flow" CEL. If the upper chamber of the EGR is sealed/capped off the actuator rod cannot move the diaphram upwards against the sealed/positive pressure chamber. If the valve cant open and allow exhaust gases into the IM passage then the sensor in that passage doesnt get hot enough exhaust gas to prevent the CEL. That phenomenon is usually caused by a clogged passage but occasionally, and I suspect in this case, a faulty/broken (non-opening) EGR valve.

If you're getting 6" of travel I can only presume you mean the actuator rod in the valve as all EGRs only have 2 moving parts, ie; plunger and diaphram. If thats the case your EGR valve has failed as that rod can never move more than 1.5mm (.061") total travel upwards from its seat (sealing position). If it can/does move more the explanation is simple; its broken away from the diaphram and/or its lower seat has fallen out (pic 2) or both and a new valve is required. The valve is not serviceable and no internal parts are available separately.

VAP

<center><img src="http://pictureposter.audiworld.com/711/egrfunction2.jpg"></center><p>This is the exhaust end of the EGR valve. In this pic you can see the "pressed-in" valve seat that the actuator rod seats against when closed. If you have more than 1.5mm actuator rod travel this may be missing and/or actuator rod has separated/detached from the diaphram. Either is fatal to the valve and requires a new EGR valve.

AudiMick

On the post 96 cars (can't speak for earlier cars) there are two modes of operation controlled by a solenoid on the top of the plenum. In normal mode the vacuum from the intake plenum opens the EGR valve at higher RPM's. There is another mode that is a self test mode that is controlled by the ECU to simulate the operation of the EGR system for OBDII. In this case vacuum from the intake manifold is sent via the second port of the same solenoid via an adjustable restrictor (to dampen the response somewhat) and operate the EGR valve.Once the valve opens the temp sensor expects to see a rise in intake temp because of EGR gases, provided that occurs no CEL is set.

Doing the EGR mod allows the ECU to self test the system but prevents the valve opening in the other mode.

Thus the valve opens less often and hence the EGR passage takes longer to clog up.

Thats probably my only reason for doing it.

Mr. Malcontent

within the valve itself, but rather the valve and the line that connects it to the exhaust manifold. When the valve was un bolted from the IM, it was still connected to the line running to the exhaust manifold. So this whole assembly was able to be moved around about 6" in any direction. Is this normal?