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Discussion Starter · #61 ·
I am also thinking putting in a non return valve between the filter and tandem pump.
Would this cause any issues?

SC
 

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I always assumed the tank pump runs for 2 seconds to prime the system when the ignition is turned on, then starts up again when cranking and the engine is running. Theoretically, the tandem pump should be able to draw fuel from the tank, but I would have thought it better to have the supply pipework under positive pressure, so as to avoid air leaks, and gas bubbles forming in the fuel under negative pressure. There have been previous threads on here where starting and running issues have been caused by a faulty tank pump.
One thing you could do, is set up a container of fuel where the supply and return pipes are dipped in, so as totally by-passing the tank and filter, and see if the problem persists. You would also see if any air bubbles are present in the return pipe.
I'm still of a mind this is a fuel supply issue, and the injector deviation is caused by air in the fuel. Even if the engine does shut itself down if the deviation is too great, it should reset itself, and start back up on 4 cylinders, and at least run for a while until it's decided the deviation is too great again, (and throw a fault code) but if I remember correctly, it won't start once its packed up?
 

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I'm still of a mind this is a fuel supply issue, and the injector deviation is caused by air in the fuel.
Me too. I thought the pump didn't run except for priming. The VW SSP for the fuel system says:
'The tank serves as a pre-supply pump, and pumps fuel to the fuel filter.' It doesn't mention it carrying on running. According to that SSP there already is a non-return valve which looks to be inside the tandem pump but that won't help if there is a leak further back. You really could do with pressure testing all the pipework (and checking the fuel filter inlet connection).
 

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Me too. I thought the pump didn't run except for priming. The VW SSP for the fuel system says:
'The tank serves as a pre-supply pump, and pumps fuel to the fuel filter.' It doesn't mention it carrying on running. According to that SSP there already is a non-return valve which looks to be inside the tandem pump but that won't help if there is a leak further back. You really could do with pressure testing all the pipework (and checking the fuel filter inlet connection).
I've also read this SSP305, and I find the wording very ambiguous! Pre-supply could mean in a fuel flow order (ie the tank pump is pre-supply, the tandem pump is intermediate-supply, and the injectors are final-supply) or it could mean the timed sequence of events. I personally read the former into that wording, but I may be wrong!

Easy way to find out- Disconnect the filter supply pipe, and crank and start the engine and see if fuel flows out of it after the prime sequence.
 

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Anyway, back to what I was doing......
Am I being a complete numpty, or does the ash load measuring block not exist for the BNZ BPC? I've looked numerous times, and can only find the soot load, which today was 75. There are 2 other measuring blocks, load coefficient, and else something similar, but these are always at zero, even after a 10 mile drive. As the ash load should be checked at the 120,000 mile service, surely there must be a number somewhere?
My Audi A6 3.0TDI has the ash load in the measuring blocks plain as daylight.
I think it should be found on the 2.5 (that actually have a DPF!) Ch 068 field 2. I only know this from it coming up about 10 years ago on Brickyard. How clogged is your DPF ?
 

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Discussion Starter · #66 ·
On another note.
How do I syphon the 3/4 of a tank of fuel out of it?
I have ran an old fuel pump and hose into the filler and have managed to get it down to half full.
But now it will not empty anymore.
There must be an anti syphon system in the tank.

SC
 

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If VCDS won't run the pump with a fuel hose open (And I'm not sure this is the case it but wouldn't hurt to try) then you could pipe up your spare pump to pull it out via the most convenient place.
 

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That's to stop it overheating. You can repeat it (since your pump is knackered anyway) but you might have to switch the ignition off and on and start again.
 

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Discussion Starter · #70 ·
OK I am getting I am getting a No response from controller message in VCDS.
Would this be my computer or a fault wirh the ecu?
I have checked all the terminals on the ecu and everything is spotless.

On another note I have seen their is sensor or something on the return line to the fuel tank inside engine bay.
What is this?
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I think it should be found on the 2.5 (that actually have a DPF!) Ch 068 field 2. I only know this from it coming up about 10 years ago on Brickyard. How clogged is your DPF ?
Well, it would appear there is a problem with the label file, ie possible translation errors.
Channel 068
1. PARTICLE FILTER LOAD COEFFICIENT 0.0%
2. PARTICLE FILTER CARBON MASS 75.0
3. CARBON MASS LEARNED VALUE 0.0%
4. (BLANK)

Carbon mass is not ash, it's soot! This value of 75.0 hasn't changed in 2 days, so very likely is the illusive ash value I've spent years looking for! If this is the case, there is no value for soot loading, and there are other channels relating to the DPF that never seem to do anything ie-

Channel 069 PARTICLE FILTER REGENERATION STATUS
1. 00000000
2. 00000000
3. 00000000
4. 00000000

Channel 070 PARTICLE FILTER REGENERATION STATUS II
1. 00000000
2. 0.0S
3. 0.0
4. 0.0

If I remember correctly, when I bought my Audi A6, the ash value was 18g, and the max value was 350g at 30,000 miles. So if my T5 had an ash value of 75g, it would seem it has a long way to go before clogged.

Apologies to the OP for sending this thread off on one! I'll start a new thread if this needs much more discussion.
 

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That's to stop it overheating. You can repeat it (since your pump is knackered anyway) but you might have to switch the ignition off and on and start again.
I've found with VCDS output tests, they won't re-run unless you close the controller down in VCDS, then re-open it and start the output tests again. Turning off the ignition freezes VCDS for a while as it doesn't know what's going on, but will reset the output tests when VCDS starts communicating again. What I'm saying, is it's quicker to close and open the controller, than turn off the ignition, and freeze VCDS for a minute or so.
 

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I've found with VCDS output tests, they won't re-run unless you close the controller down in VCDS, then re-open it and start the output tests again.
Good tip. If just closing the controller works then great. But if not, a switch ign off/on may be needed.

Re the DPF channels- I'm not really up with all of the DPF stuff. Personally I wouldn't even buy a diesel these days unless I was a higher mileage user. Adblue is adding another complication. But then I am an old duffer!

Re Gregozedobe's post in my link, I know from the last ten years or so that Greg prefers accuracy and doesn't post BS. I can tell that his 'DPF Query' comes from VW dealer diagnostics because of the way it is written. Their own labels should be fairly reliable you would think.

VCDS allows open source for label files and encourages the many enthusiasts to take part. They are checked for reasonable accuracy I would assume. But that doesn't mean things can't be mis-labelled.

I don't know how it is these days but I remember that most good VW techs had VCDS alongside their own official kit. ;)

Re DPF's generally- Over to you for that (and a new thread) I'll be watching and learning but I certainly don't know enough to add very much.

Happy Christmas to all by the way! :)
 

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Discussion Starter · #76 ·
The VCDS is coming up with this message whilst running.
Is this just a software fault or is it something else?
This is now the second Christmas I have had this fault.
The only difference is after a while when things have warmed up the deviation values of all the injectors end up at either - 2.99 or +2.99 then shuts down.
These values are not consistent as I have now ran up 3 times with this fault and it is on different injectors which are plus or minus.
My thoughts on this is this is a fuel issue and as the fuel supply drops the injectors are trying to compensate for this.
Sadly on another note it would take a week to empty the tank with the fuel pump, so I still haven't managed to remove the fuel and change the fuel pump.
Lastly whilst it was last shutting down I managed to turn the fuel pump on and the revs did rise. But once turned of it stalled.

Merry Christmas everyone.

SC
 

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The VCDS is coming up with this message whilst running.
Is this just a software fault or is it something else?
It is quite unusual to lose communication with a controller in the middle of a session. Have a look at the LED's (if your cable has them) on top of the cable where it plugs into the van. It should go to solid green when you first plug it in (with ign on) and flicker when data transmission is occurring. If it goes back to amber when you move the cable slightly, the connection may be poor.

So It could be the cable connection or the ECU or wiring to the ECU . When it loses communication with the engine ECU, see if it will connect to another controller (like say, CENT CONV). Lastly if the battery voltage gets low during a long session that can do it. You can leave a battery charger connected while you are working to keep the voltage up.
 

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I have something similar with our 2005 Kombi, and it seems like I can solve it by changing the comms rate. The van's not here at the moment so I can't check, but IIRC if you click on the "Turbo!" box, you can drop the comms speed down - on ours it then works Ok without losing comms.
 
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