tester123

I've been dealing with these codes:

17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - - - Intermittent
16825 - EVAP Emission Control Sys: Incorrect Flow
P0441 - 35-00 - -

The funny thing is that 16825 is new and hasn't showed up again. The 17549 is usually tagged with 17544 & 17546 (Fuel banks 1&2 lean).

I try clearing codes and go through VAG-COM to generate readiness code (as per Bentley manual), all items pass but, in due process, CEL is back on again. And this process is stuck in a loop.

I checked Mass Air Flow and it is well within specs.

The EVAP code is new, will check to see if the valve is working properly..

Used to have Secondary air issues but resolved them as vacuum hoses were shot. Replaced those and codes related to this are not there. But, not sure if there are any other vacuum issues.

any other ideas?

Edd W

Have you tried throttle adaption?

Kris Hansen

You may need a new MAF. I had the same issue with my A4, and a new MAF cured it, along with re-crimping the clips in the harness on the MAF.

tester123

Would one see Load Calculation (17549) error due to out of spec throttle adaption?

I am no master at this but, if you had experienced similar, I can give it a go and see what happens.

Thanks for the response!

Kris Hansen

No, I tried and tried, adapting the throttle doesn't help.

tester123

I am leaning towards MAF or a hard-to-trace vacuum leak some where in the system - esp. due to the fact that I found hoses going to combi-valves were literally torn open and replaced them. I might be missing another somewhere.

However, how can I conclude it is MAF when during the VAG-COM group (002) I believe, shows well within specs as per manual?

I am just perplexed at this.

Kris Hansen

If the MAF is bad, it may not know it's bad, so it's readings will disagree with the throttle position sensor etc..

tester123

ahhh, hence, the suggestion to perform throttle adaption!

ok, I may be beating this question to death but, during the test, with RPM at 680, load at xx.x, and engine temp, voltage etc. within the testing range (again, as per manual), the MAF's output was perfectly in spec and not high or low... so doesn't that mean it is good?

I guess what I am saying is that say MAF is wrong (not failed completely), wouldn't the output of it show variance in terms of reporting to ECU and therefore in OBD? In my case, it is in spec that's why I just baffled. Can you shed more on this if you could?

Kris Hansen

Mine claimed to be within spec too, at least for a while, till it started to get worse and worse. I got a new one, and fixed up the wiring, and it was perfect.

You might have a go at fixing the wiring first, make sure that each of the wires makes good continuity back to the harness on the ECU. I don't have the pinouts handy, but can get them tonight.

tester123

I finally opened the front left wheel well to check the second reservoir lines and they are also good. Just one question here, there is "non-return Valve" connected to the intake manifold. Couple questions here:
1) Is the vacuum for the system generated through this?
2) I put a hand vac pump to test and one side is free (towards the manifold) and the other side is losing vac slowly. Is this correct operation? I couldn't find any details in my manual on the correct operation of this valve.

To me, it sounds like the vacuum is generated through the intake manifold and stored in reservoirs as well as used by the operation of valves (i.e. manifold flaps, secondary combination valves etc.) but is this vacuum supposed to be maintained after the engine shuts off? If this "non-return valve" blocks completely, it would work that way. But in my case, the valve leaks slowly on hand pump so not sure if that's supposed to do that.

Also, on the side note, I checked the hand vac pump on the lines (connected it to the lines "Y" adapter right after the non-return valve -bypassing it) and there are no leaks. Vacuum is holding all through out the system (i.e. reservoirs etc). Is it safe to say the lines are good? Or, is there somewhere else I should test to ensure all lines are ok?

I cleared the codes again and nothing showed up yet. Will take it for a test drive and see if they come up again.

Please share your thoughts.