D3 Intermittent Start Fault

woodpoleman · #1 2nd November 2016, 08:43 AM

I have a 2005 D3 3.0 TDI Quattro with an intermittent fault since May. Car will start but sometimes there's a lag between turning the key and starter kicking in and when out and about after a couple of stops will not start. Turn the key hear relays clicking but starter does not engage. Leave it a while (can be 30 mins - 2 hours) it'll start again. My garage has replaced starter ecu, ignition switch, starter motor. I've replaced engine coolant sensor and starter relays. Audi re-coded ecu, replaced and coded new battery. Audi had the car for two weeks started 4/5 times each day but never drove it so fault never occurred. Any help and ideas will be gratefully received.

M-A8 · #2 2nd November 2016, 08:55 AM

Can you post a full VCDS scan??

woodpoleman · #3 2nd November 2016, 12:09 PM

Thanks for the reply but I don't have VCDS information. My garage uses a third party for in depth diagnostics who wants to extract all fault codes for subsequent analysis. Sorry I can't be clearer than that.

PsYcHe · #4 2nd November 2016, 12:55 PM

Is it worse when it's been raining? My 2003 D3 had an issue with water ingress when I got it, which caused issues with starting.

Joe2.0E · #5 2nd November 2016, 07:09 PM

Could be as simple as an earth strap on the starter or even the battery.
When you say "replaced", are they new parts or from a breakers ?
Could be a suspect replacement part.
Before spending anymore on parts, it might be more prudent to get the car to a decent auto-electrician.

M-A8 · #6 2nd November 2016, 10:33 PM

Well, I would say get the full scan done by one of the local to you forum memeber (look in the vag com register thread) and post the results so we can have a look.
It looks like they may be using basic scanner where they cant see the whole scan so they just keep changing parts using the lottery strategy.
With A8s in most cases you need to look at the entire scan before making the call what to change first.
For example an ABS fault can be caused by a faulty steering angle sensor and I've seen people having ABS pumps changed.
Battery fault caused by faulty battery ECU so no need to change the battery just the module and so on.
One faulty component can trigger fault codes in few other components and if they have limited knowledge about A8s you will end up having all the parts changed but not the one which actually is causing the problem which could be the case here looking at the list of stuff you've had replaced.

woodpoleman · #7 6th November 2016, 07:19 PM

Quote:

Originally Posted by woodpoleman

I have a 2005 D3 3.0 TDI Quattro with an intermittent fault since May. Car will start but sometimes there's a lag between turning the key and starter kicking in and when out and about after a couple of stops will not start. Turn the key hear relays clicking but starter does not engage. Leave it a while (can be 30 mins - 2 hours) it'll start again. My garage has replaced starter ecu, ignition switch, starter motor. I've replaced engine coolant sensor and starter relays. Audi re-coded ecu, replaced and coded new battery. Audi had the car for two weeks started 4/5 times each day but never drove it so fault never occurred. Any help and ideas will be gratefully received.

Thanks to everyone for their interest and advice which has been appreciated. I'm getting a scan this week and will let you know how it goes.