austinado16

Well, my CEL is back on and giving the good ol' "insuficient flow" EGR code.

This after I found the EGR solenoid was bad, replaced it, along with all the cloth braded vacuum lines (and previously had cleaned out the EGR passage and confirmed function of the EGR Valve, and EGR temp sensor.

So, more testing today:
1) Pulled a vacuum on the EGR valve and watched the EGR temp sensor respond using VAG-Com measuring value block 17, window 4. Checked okay as I got a temp reading above 65*C in about 20 seconds.

2) Using VAG-Com in output test mode I pulled a vacuum on the vacuum supply line for the whole emmissions system while actuating the EGR Solenoid. With a vacuum gauge T'd into the EGR vac line, I had a pulsing vacuum reading.

2) Went for a test drive with a vacuum gauge taped to the windshield and T'd into the vacuum line at the EGR Valve. Had decent vacuum reading under light throttle at 48mph-62mph.

And during the test drive, no CEL. I pulled over a couple of times, shut the engine off, restarted and put the car back into its EGR test mode. Finally, on the 3rd attempt I got the CEL back on.

The only thing I can think of is that the EGR Valve itself is sticking closed. It may respond when I pull a big vacuum on it with my Mityvac hand pump, but it's probably not responding under the lesser vacuum supplied through the EGR Solenoid. My pulling a vacuum on it at the beginning of all my testing probably got it unstuck temporarily.

$250 for a new EGR valve. I think I'll live with it for a while because that's about 2 ski trips.......if ya know what I mean!

islingtonaudi

I got an extra one me thinks but email me and we can confirm it's correct

austinado16

Thanks Doug, YGM

Amadeus

I have not worked on mine for a while, but on the vac solenoid there should be a screw. My mechanic told me that this adjusts the amount of vacuum that is sent to the EGR valve. Some valves need more than others - age, heat, cold, etc.. They have had some success with simply turning the screw to alleviate this kind of intermittent condition. May be worth a try.

austinado16

When I was doing vacuum tests on the entire system a few months ago I noticed that vacuum was 25" or so up at the manifold, but once it got down past the little black goody on the side of the EGR Solenoid Valve, it was much less and I wondered why they would want to limit it so much. I actually thought about just elimating that little black valve assembly. But, I found that the Solenoid wasn't working, so I replaced the whole thing, and it came with that black valve.

I've still got the old black valve, so I can play with the screw in it first.

Thanks for the tip!

kday

This is the plastic thing that connects between the U shaped hose and one of the vac lines?

austinado16

The black "vacuum control valve" (I'm making that term up) just snaps on to the outside of the solenoid valve's metal body.

Just played around with my old one. Turning the screw outward (counter-clockwise) opens up the valve and allows more suction.

As soon as I can pry the Avant away from the wife, I'll put this old one on, with the screw opened up quit a bit, and then give 'er the ol' test drive.

mulsannekink

I have found that carbon builds up around the temp. sensor thus insulating it from the exhaust gas. The repair is to remove the temp. sensor and with the largest drill bit that will fit in the port clean out the port. NOTE the drill bit should be held in your handand used to scrape out the carbon don't use power tools

Audi Logic

do you have a pic of this valve?

austinado16

<center><img src="http://pictureposter.audiworld.com/57225/egr_vacuum_control_valve.jpg"></center><p>It's the black box there with the "P" stamped on it, and that off-white button in the center. Pop off that button, and there's an adjustment screw living underneath.