OK, have had this nagging issue for some time and want to get it sorted before smogging the car later this year.

1998 2.8 QM Avant.

Read many posts on AF and other Audi sites, but did not find any relevant solutions. Have a VAG-COM with latest software, and Bentley Manual.

Essentially the car will not give "Readiness" for the EVAP System due to the LDP-V144 not being able to run it's pressure test. When the 071 group is tested, it displays "Valve Closed" for a few minutes, then "Aborts". The only time the valve shows "Open" is when the ignition is in the on position, but not turned on. All other systems give "Readiness" codes.

The LDP was replaced last month at a local shop, based on their feeling that it was the issue and a smoke test...still not clearing and still same exact problem as before.

Need help moving beyond the testing I have done so far to sort this one out....experts, please chime in.

Here are the details so far:

1. Have tested using VAG-COM - Group 070 - N80 Purge Valve = OK. Makes all the right noises and passes the test.

2. Have leak tested the vacuum line which goes from the motor directly to the LDP; no leaks.

3. Have tested the line from the N80 to the charcoal canister = OK, no leaks.

4. Have tested the line from the LDP to the charcoal canister = no leaks.

5. Have checked the gas cap, filler, and related lines = no leaks.

6. Have tested the pressure in the system (manually inflated) from the LDP to the charcoal canister, no bleed-down.

7. Tried testing the LDP with the line going to the charcoal canister disconnected...believe that when running the 071 group test the pump should put out a decent amount of air, and give a massive air failure...but absolutely no air pumps out of the pump! This is the essence of the problem, no pressure generated from the pump.

8. When took it to local shop they performed the smoke test. The only area where smoke came from was the air filter on the LDP itself; thus is making it's way through the N80 and charcoal canister, or via the vacuum side of the LDP. They replaced the LDP...as noted above did not fix the problem.

9 Tested the new LDP for resistance; it is well within the specs of the Bentley Manual.

10 Tested the LDP plug with the ignition on and get the following values T1 = .06V, T2 = 5.92V, T3 = 13.75V

11 Assume that the Fuse is OK, since the fuel pump is working, also assume that the fuel pump relay is also OK, since the fuel pump is pumping (correct me if these are false assumptions).

12 Don't have VAG 1598/22 tester to test harness from ECU to LDP plug.

13 Noticed that any pressure in the gas tank goes right through the Carbon Canister and out the LDP air filter...not sure if there should be some of check-valve preventing gasses from venting to the atmosphere...thought that was the whole idea of this system. So, if the car was parked never does it build up any pressure in the tank. Open the gas cap and nothing. Compared to my 1.8T which has the normal whoosh of pressure when opening the cap to fill the empty tank.

Sorry for going on an on, but have tried to document everything I could think of hoping someone could shed some light (beyond taking to the stealership).

BTW - getting to the LDP is a real pain.

 

If you find yourself in a similar situation where you can not get your Readiness Codes to fully clear, try resetting the ECM/ECU with a full unplug to clear out all memory.

This was what I did recently after replacing one of my O2 sensors, clearing all of my Fault Codes and once again having problems with the car clearing Readiness. It worked like a charm. All codes and systems passed within one try.

 

good to see that your problems have been resolved