Audi A6 2.7T cranks but won't start

[eejit]

I've recently got myself a 2002 A6 Avant 2.7T Quattro Manual (about 2 months ago). Prior to this I've had Mondeo's and Volvos and have been able to do work on them myself (so I'm quite disappointed to find out that there's no Haynes Manual for the C5 A6!).

Recently it's been taken longer to start, and having come back from a holiday is now completely failing to start. The starting process sounds absolutely normal, it just will not take. My initial thought was temperature sensor based on this thread from Audi-Sport forum. I've read all the codes I can with an Autel EU702, it comes up with the following codes:

17861 - P1453: Exhaust Gas Temp Sensor 1 (G235): Open or short to plus.
17865 - P1457: Exhaust Gas Temp Sensor 2 (G236): Open or short to plus.
16825 - P0441: EVAP Emission Control Sys: Incorrect Flow
18010 - P1602: Power Supply Terminal 30: Voltage too low

Surely a faulty temperature sensor would cause a code? I've unplugged the sensor anyway as the above thread suggests and it still won't start. I'm writing off the P0441 code as a bit of Googling says that won't cause the start issues. Googling P1453 and P1457 would suggest that if those stop working the car would just assume that they were at the maximum temperature and overfuel, again not causing the car to not start. Can anyone offer an alternative opinion on that?

That would leave me with just P1602. Now the battery is definitely dead - I connected a power pack to it today to crank it, it was definitely only cranking off the power pack, and when I unplugged the power pack I watched the needle drop from 8-10V to zero in the space of about 3 seconds. I've now replaced the battery and it will crank again but I'm keen not to kill this battery straight away - is there something else relating to that fault code that I should check?

Also, I cleared all the fault codes to see if I could narrow it down to whatever's causing the car not to start, and now there's just no fault codes. Any thoughts?

Thanks in advance.

[eejit]

Additionally. I had to get a tow from a mate to get my car back to my flat tonight. Turning the wheel with the engine off appears to have caused a power steering fluid leak - from the top of the reservoir. What sort of damage may I have caused? What should I look out for? Or will it just be a case of getting a new seal?

[zollaf]

thats usual when you turn the wheel with the engine off, nothing to worry about. its just the rack pushing a load of fluid back to the resevoir. just top it up when you get it running and turn it lock to lock a few times then let it settle and recheck the level.

[ceilidhalfie]

Hi eejit Is this a diesel? If so, is the fuel filter above the plenum filter on the driver's side and does it have 4 fuel lines going into it? If answers are yes, then it is like my 2002 Allroad.
When you got the car, I assume it started ok each morning? Did you ever leave it parked up for 2-3 days or more and then find it was a bit relictant to start? Again if answers are yes, I think it likely you have an air leak. When I botched a fuel filter change on my Allroad I managed to crimp the little o-ring on the valve and that let air in. If car was left for a few days, the fuel drained back into the tank emptying the fuel lines. With the Allroad, the only pump is the Injection Pump which takes for ever to prime the fuel lines - battery will flatten usually before engine will start.
As you have a new battery, put an electric pump in-line between the filter and IP and connect to battery. Run this pump whilst cranking the engine - only run pump for a few seconds, then stop, then run again whilst cranking the engine (too avoid over pressurising the fuel line). The electric pump will prime the fuel lines and car SHOULD start within 10 seconds. If it does start, then you do have an air leak SOMEWHERE - not neccessarily at the fuel filter. If the air leak is small, the engine should start if not left standing for more than an overnight. Keep using the electric pump until you find the source of the air leak - and conserve your new battery.
Hope the above helps.

[eejit]

Hi eejit Is this a diesel? If so, is the fuel filter above the plenum filter on the driver's side and does it have 4 fuel lines going into it? If answers are yes, then it is like my 2002 Allroad.
When you got the car, I assume it started ok each morning? Did you ever leave it parked up for 2-3 days or more and then find it was a bit relictant to start? Again if answers are yes, I think it likely you have an air leak. When I botched a fuel filter change on my Allroad I managed to crimp the little o-ring on the valve and that let air in. If car was left for a few days, the fuel drained back into the tank emptying the fuel lines. With the Allroad, the only pump is the Injection Pump which takes for ever to prime the fuel lines - battery will flatten usually before engine will start.
As you have a new battery, put an electric pump in-line between the filter and IP and connect to battery. Run this pump whilst cranking the engine - only run pump for a few seconds, then stop, then run again whilst cranking the engine (too avoid over pressurising the fuel line). The electric pump will prime the fuel lines and car SHOULD start within 10 seconds. If it does start, then you do have an air leak SOMEWHERE - not neccessarily at the fuel filter. If the air leak is small, the engine should start if not left standing for more than an overnight. Keep using the electric pump until you find the source of the air leak - and conserve your new battery.
Hope the above helps.

Not a diesel, petrol V6. Thanks anyway.

[eejit]

thats usual when you turn the wheel with the engine off, nothing to worry about. its just the rack pushing a load of fluid back to the resevoir. just top it up when you get it running and turn it lock to lock a few times then let it settle and recheck the level.

Thanks, that's a relief!

[bluezie]

I would check for a good spark at all plugs, then check for fuel at the rail and fuel rail pressure. The engine should start with the codes you had above - the terminal 30 low voltage is because you killed the battery tring to start it.

[eejit]

I would check for a good spark at all plugs, then check for fuel at the rail and fuel rail pressure. The engine should start with the codes you had above - the terminal 30 low voltage is because you killed the battery tring to start it.

I'm not sure how to do this - would this suggestion be based on maybe the fuel pump being dud or the fuel filter being blocked? I saw this as a suggestion on another forum for an allroad 2.7t and it turned out to be his fuel pump. I tried to have a listen for the pump priming today but when you're on your own it's difficult.

I'm also replacing the Crank Position Sensor as it's a cheap part and that was a suggestion for something that might cause it not to start but not generate a fault code.

[eejit]

A couple of things I noticed today:

This hose doesn't seat well on whatever this canister is:
http://i.imgur.com/NczuaBi.jpg
This is on the left side at the back as you look at the engine, the similar one on the right is well connected. Would this cause any issues?

And this sensor doesn't appear to be plugged into anything, it's just hanging loose. It's connected to the positive battery lead. Looks like it's maybe just an ambient temp sensor or something so I imagine not too important?
http://i.imgur.com/MZR4qEU.jpg
I'd like to know where to plug it back in though.

[eejit]

So, I've now fitted a new Crank Angle sensor (which was a pig to do), car still won't start. I now suspect the fuel pump - can't hear it priming or pumping when the engine cranks. There is voltage across pins 1 and 4 at the connector - this should rule out any electrical issue, relays, fuses etc, correct?

I have bought a fuel pump anyway and will fit it upon arrival. TBH this will probably be the last thing I do before giving up and taking it to a garage for a diagnosis.