My BKD won't fire up - & Canbus seems not be working

[jeallen01]

Good afternoon (NOT!)

 

The short(ish) story:

- last Tuesday I drove the car for about 10 miles, and everything was fine;

- did not use on Wednesday, and then when I went to start it on Thursday afternoon it would not fire up although the engine was turning over quickly (new Bosch 96AH S4 battery about a year ago, so it's not a flat battery, etc.), and it was the same about 5hrs later;

- today, the same rapid engine turn over but no firing, and also no Warning Lights that fail to extinguish after the engine has turned over for a few seconds (apart from the handbrake one because the brake is fully ON!). OTOH, most/all the auxiliary electrical functions (lights, indicators, heater, OEM-fit radio, aircon/climate control, central locking, etc.) seem to be working as normal. 

 

Therefore I started to try to do some investigation with both the TORQUE app on my tablet connected to a Bluetooth dongle plugged into the OBD socket (this combo has worked before on the same car) and then with a cheap "VAGCOM" lead and VAGCOM 12 combo (this has also worked before on the same car - and, before anyone asks, I DID have a gen VAGCOM lead but I think someone nicked it when the vehicle was being serviced a few years ago, and I could not afford to replace it!).

 

However, neither combo appears to be able to communicate with the ECU, and the VAGCOM s/w can't locate any of the individual controllers.

 

BTW: This BKD engine has a tandem fuel/vacuum pump and does not appear to have an electric one (my very first thought was that there was a fuel pump/relay/fuse problem, but I can't see that being the problem now!).

 

BTW2, I've checked all, and re-seated most, of the fuses in both the cabin and engine bay fuseboxes and none of them have blown.

 

Since then I been doing a little on-line searching to try and see what the problem(s) is, and all I can find amounts to:

- blown ECU (I really hope not! - and I somewhat doubt it because of all the auxiliary functions that seem to work)

- broken wiring "somewhere" in a cable to the ECU.?

- poor chassis earth connection(s) "somewhere"?

-.???????

 

FWIW, AFAIK, the dashboard has never been removed, and the last major work in the engine bay was over a year ago when the turbo (and then its replacement :-( )  blew - so little likelihood of any very recent physical wiring disturbance or damage,

 

So, I'm at a loss as where to start looking more deeply and would be grateful for any suggestions

[FLAPPERJACK7]

You will still have an electric lift tank pump. Try disconnecting the battery . Leave it off for half an hour. Reconnect and try it.

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[jeallen01]

You will still have an electric lift tank pump. Try disconnecting the battery . Leave it off for half an hour. Reconnect and try it.

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I'm not sure that this model does have a lift pump in the tank  - the ElsaWin diagram of the tank assembly does not show any electrical pump or connections to one, but just the fuel tank sender assembly with 2 electrical connections to it.

 

OTOH, if there is a lift pump, then please can you tell where it is?

[jeallen01]

Also, might the problem be to do with the direction injection system relay (J322, I think) on the relay panel behind the lower edge of the driver's side dashboard?

(will take the panel out tomorrow and fit a new relay anyway if the weather is OK  - the car is parked on our front block-paving, and that's a  100 yds push, from the garage at the rear of the garden and so working outdoors is the only option!)

 

PS: does anyone know the VAG P/N for J322 so I can try to get the correct replacement before I take the old one out?

Edited 16 April, 2016 by jeallen01

[FLAPPERJACK7]

Under rear seat. Black cover on driver's side rear. If you don't have one I will eat my own underpants.

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[FLAPPERJACK7]

Try disconnecting battery 1st. It costs nothing and has fixed many a non start for me. It's just like turning off and restarting a computer and you know that normally works at home. If that does not work with starting it might with communication. Other than that maybe can bus has gone down. Or my next thought would be a faulty injector. If one goes down it will not start. But it's way easier if we can access fault codes.

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Edited 16 April, 2016 by FLAPPERJACK7

[jeallen01]

FLAPPERJACK7, on 16 Apr 2016 - 18:12, said:FLAPPERJACK7, on 16 Apr 2016 - 18:12, said:

Under rear seat. Black cover on driver's side rear. If you don't have one I will eat my own underpants.

Sent from my SM-G900F using Tapatalk

Many thanks!

 

I think your underpants are probably safe, as you appear to be perfectly correct about the location of the cover and the connections underneath it - although I have only removed the felted cover above it, I can see a 5-wire connection going through a round plastic cover to what looks like the tank.

 

However, with that area exposed I then turned the ignition on/off several times and could hear a whine from that area for about 2 seconds each time - so I think the pump seems to be working, although whether it is actually pumping fuel is another thing.

 

Elsawin instructions show how to use a special VAG control unit (which of course i don't have) to test the pump after disconnecting the fuel feed pipe to send fuel into a container - could I do the same test just by disconnecting the pipe and, with another bit of pipe to a container, turning on the ignition switch for a few seconds?

Edited 16 April, 2016 by jeallen01

[jeallen01]

Try disconnecting battery 1st. It costs nothing and has fixed many a non start for me. It's just like turning off and restarting a computer and you know that normally works at home. If that does not work with starting it might with communication. Other than that maybe can bus has gone down. Or my next thought would be a faulty injector. If one goes down it will not start. But it's way easier if we can access fault codes.

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Thanks again - I'll try that first thing tomorrow morning (it's getting cold out there now!).

 

Hoping it's not the injectors because they were fully cleaned and serviced by a local diesel specialist about 2yrs ago and everything has been pretty much absolutely fine since then, and the engine (turbo woes apart) has run very cleanly and consistently with no signs of misfires (apart from very occasional irregularity for the first couple of firing strokes on a cold morning, but nothing like that recently).

 

This current failure happened totally out of the blue, and so an electronic "glitch" might well be the cause - but that would still leave the worrying questions of why it happened, and could it happen again? 

[FLAPPERJACK7]

Looks like the tank pump is working then and like you said my underpants are good for a while. You could disconnect the fuel pipe at the bulkhead put the ignition on to make sure it's being lifted to the fuel filter. It is the black pipe you want to disconnect. Black is feed and blue is return . Really a dtc code would be ideal. See how you get on. Update when you can. An injector failure can happen at any time. The ecu on this engine if it sees a fault from the injectors will shut it down immediately. I may be jumping to conclusions here. Could be an earth problem like you said. Main earth points will be in the scuttle near the ecu. One high on the chassis nsf. About 3 nsf lower chassis leg all connected together. Possible one on osf chassis leg. Should also be a small one on the engine itself from the engine wiring loom. Wire breakage is common especially around starter motor and any sharp points on the engine.

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[xman]

Have you checked you've not run out of fuel? Or put petrol in by mistake?

[jeallen01]

Have you checked you've not run out of fuel? Or put petrol in by mistake?

There is just less than a quarter of a tank of fuel, and I have not put any in for about 3-4 weeks (I'm retired and don't do a lot of mileage now) - so I don't think either of those possibilities are the cause.

 

OTOH, I did add a container of Cataclean to the remaining fuel a few days ago because the MoT is due soon and most of the recent mileage has been short journies.

[jeallen01]

Sunday update

 

As suggested, I disconnected the battery this morning and left it like that for about 3hrs whilst I did other things before reconnecting it.

 

Then I tried to start the engine

- 1st time turned over for about 10s without firing, switched off

- 2nd time - same as 1st

- 3rd time - after a few secs, began to hear attempts to fire but nothing regular

- 4th time - same as 3rd until 1 or 2, and then finally all 4 cylinders started firing and then the engine revs settled down and so I kept it running for a couple of minutes.

 

Then switched it on and off several times and it started and ran each time, so left it for about 10mins to start to recharge the battery (good job that is large capacity and quite new, or I might not have got that far anyway)

 

Tried to connect Torque on the tablet to the BT dongle in the OBD socket but it would not connect.

 

Connected the VAGCOM lead and fired up the laptop with VAGCOM - got a connection to the engine management system this time! So I  ran an autoscan which threw up various minor faults including the steering angle sensor (that LED was/is still illuminated) and one relating to the CANBUS (hoping that was a stored and not live one), plus various other minor issues which I don't consider very important at the moment. Have saved the log on that laptop, which is not the one on which I'm writing this post, so can't post the log at the moment.

 

Now trying reload all the Fault Codes so that I can try to delete them and see what happens afterwards.

 

Any comments on the above would be appreciated

[jeallen01]

Cleared all the existing codes and then reran the autoscan - and only the steering angle fault code and LED symbol is still there now. IIRC from other threads, that one should disappear after the vehicle has been driven for a bit and everything syncs up properly again. Therefore I think (at least I hope!) the electrical side of things is sorted (well, maybe).

 

OTOH, the question as to why this all happened in the first place is still unanswered.

 

Because of the amount of turning over this morning before the engine finally fired, I think that letting the vehicle stand for a couple of days allowed fuel to drain back into the tank because of the failure of some sort of non-return valve (NRV). I believe there is an NRV in the combined fuel/vacuum pump (on the end of one of the camshafts) but that unit is said to be unrepairable (and costs >£300!) and so changing it would be a last resort.

 

Therefore, where else might there be another NRV that could be changed, &/or is there a way to fit a separate NRV into the fuel supply line, and if so does anyone have any suggestions for a part to use?

 

PS to MikeH, I did get the non-gen VAGCOM lead to work this time, and - given that I need to use one quite rarely - I don't fancy shelling out over £300 to replace the gen one that got nicked some years ago unless there is absolutely no alternative.

 

PPS: thanks to all the people who have given help and suggestions on how to sort out my problem.

Edited 17 April, 2016 by jeallen01

[jeallen01]

Bump for suggestions for NRVs to insert into the fuel lines?

 

BTW: started the car yesterday and today with no problems - but it was only standing for about 12-15hrs between the starts.

[jeallen01]

Update:

 

The car has been running fine since I restarted it on 19th April and I still have no clear idea of what happened to prevent it starting, or why (apart from the battery disconnection and ECU reset process) it did finally restart after a few days..

 

However, then I read the article on ECUs in the June issue of Car Mechanics (which came yesterday) where there are "Top 10 Engine ECU failures" listed - and No 10 (on Page 15) relates to the Passat 2.0 TDI where it states"

 

"The engine ECU is a very common failure that will cause the engine to either cut out while driving or fail to start. The fault may occur intermittently and the engine might restart after a short period. For 2011-2015 cars, the ECU can be water damaged, due to poor drainage from the plenum chamber under the windscreen. If trying to read fault codes, diagnostic equipment might not communicate with the engine ECU, as well as other ECUs, including ABS or the instrument cluster"

 

Whilst my car is earlier than the period stated above, from what I think I know, the general configuration of the location of the engine ECU in relation to the plenum chamber under the windscreen on the Octy II is somewhat similar to that described for the Passat, and the symptoms outlined are eeriely similar to what appeared to happen in my case because I had the issue that VCDS (and Torque on my tablet, via Bluetooth) would not communicate with the ECUs.

 

Therefore, has anyone else experienced water ingress into the engine ECU on this generation of Octy II?

Edited 17 May, 2016 by jeallen01

[mannyo]

I've never heard of any member on here having ECU problems during my extremely long membership.

 

I am going to hazard a guess, that the canbus went down before you disconnected the battery. This can happen for all sorts of reasons, It's happened on my Audi once in the 2.5 years i've owned it. After that happened, all the attempted restarts possibly flooded the engine with too much diesel. You then disconnected the battery which reset the canbus and got everything working again, however the engine was flooded so took a lot of cranking to get out some of that fuel and once the mix was about right it eventually fired.

 

May not happen again, but you can never tell.

[jeallen01]

Mannyo

 

Thanks for the comments and info - it's the "but you can never tell" bit that kinda worries me!

[vmdumitrache]

Hello everyone,

 

I'm very sorry for digging out an old thread, but I seem to have similar issues to the ones described in this topic (plus a few others) and I found it relevant to add more info to this discussion.

 

The car I'm writing about is a 54 plate Audi A3 (2.0 TDI BKD engine) which I just bought a few days ago. The previous owner says that he ran out of diesel whilst driving. After having added about 8 liters, he couldn't get the car to start. I put some more diesel into the tank (just to make sure) and tried it myself, but to no avail...

 

After some testing, the problem seems to be the same: I can't connect to the ECU and it seems that the fuel pump is not priming. I've done some fiddling around, took the pump out, tested it with a charged battery and it seems to have gripped - it just torqued once and that was it. Changed it with a spare one, which I assume is working.  No success either...

 

I've also checked all relays (I have no idea if I'm missing any, but it doesn't seem to be the case).

 

Aside from this, I also probed all the pins from the fuel pump plug (assuming brown is ground) and checked for voltage when opening the door and when switching the ignition to the second position. No voltage seems to reach the fuel pump plug itself. I've followed all the wires up to the engine bay and they seem to be all right. Fuel pump positive doesn't seem to be shorted to ground at any point and, overall, that section of wiring presents itself in good shape. It's worth noting that the fuel pump relay (449 relay) which is underneith the steering wheel isn't getting triggered. I've tested the relay and it works. Just to make sure, I've also swapped it for the 449 on the horn. Still does not work.

 

Other things I did were to check all of the fuses (both those in the engine bay and those inside the car). When checking / replacing those inside the car, I've noticed that fuse 35 (5A) gets instantaneously blown (regardless of how the ignition is positioned, or if the key is not present). The cover from inside the car says that fuse 35 is "Convenience electronics (ctrl unit)". Online, I've found it to be the Alarm System, so that's some conflicting info...

 

Sorry for the long initial post, but I thought it would be best to share all my findings, as they might connect in a way that I'm not aware of.

 

I'd love to hear feedback from those who've experinced similar issues.

 

Cheers!

[jeallen01]

1) Have you tried disconnecting the battery for a few hours so as to re-set the ECU - that seemed to work for me earlier this year.

2) Early BKDs didn't have a non-return valve in between the fuel filter feed to the cylinder head and the port into the head - meant that diesel could drain back into the filter and so none gets to the injectors. OTOH later engines did have such a valve - and it's fitted to all new replacement VAG fuel harnesses (for nearly £200!) from the filter to the head. Recently fitted a valve (genuine VAG, and that's £23, but you can buy equivalents from ebay for less than a Fiver!) and that seems to have made a quite bit of a difference, even though it does occasionally take a few turns of the engine to get it to fire up. If you search my threads, you should find the one where I described doing that.

PS: that thread is here

Edited 10 September, 2018 by jeallen01
Updated

[vmdumitrache]

38 minutes ago, jeallen01 said:

1) Have you tried disconnecting the battery for a few hours so as to re-set the ECU - that seemed to work for me earlier this year.

2) Early BKDs didn't have a non-return valve in between the fuel filter feed to the cylinder head and the port into the head - meant that diesel could drain back into the filter and so none gets to the injectors. OTOH later engines did have such a valve - and it's fitted to all new replacement VAG fuel harnesses (for nearly £200!) from the filter to the head. Recently fitted a valve (genuine VAG, and that's £23, but you can buy equivalents from ebay for less than a Fiver!) and that seems to have made a quite bit of a difference, even though it does occasionally take a few turns of the engine to get it to fire up. If you search my threads, you should find the one where I described doing that.

PS: that thread is here

 

Thanks for the insight!

 

I've just taken the battery off about an hour ago. I really hope that will breathe new life into it, but we'll have to see.

 

Regarding your second point, I haven't noticed any non-return valves, but I'll be sure to have a look. Before that, I still need to get power to the lift pump...

 

[Guest]

To get things going why not use some easy start spray and take it from there.

[jeallen01]

13 hours ago, vmdumitrache said:

 

..Regarding your second point, I haven't noticed any non-return valves, but I'll be sure to have a look. Before that, I still need to get power to the lift pump...

 

You said your AUDI is a 54 plate - so it almost certainly doesn't have the non-return valve (my 07/57 plate Oct didn't until I fitted one)

 

[Tech1e]

When cranking does the rev counter move?

[vmdumitrache]

Hmm, that's something that I haven't looked at. What would it mean if it did / didn't?

[SuperbTWM]

55 minutes ago, vmdumitrache said:

Hmm, that's something that I haven't looked at. What would it mean if it did / didn't?

Means the crank sensor is duff