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D3 - Common Faults Quick links to all known common faults and their solutions

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  #11  
Old 8th June 2017, 06:54 PM
erubus erubus is offline
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What is the largest CCA battery I can fit without frying the electronics? There is an 850 CCA one fitted at the moment but I will be refitting the 900 that was in it originally. Can I fit something much larger as long as it's physically the same size? perhaps that will be enough to give the engine that little more oomph. It's definitely getting harder to start. Last night i had to wait four hours before it started and when its cranking repeatedly for ages all sorts of things usually start going wrong, like the wing mirrors going permamnently dark.

Tonight when I tried starting it and it failed it was only 60 degrees. Its really getting to be quite annoying. I cant really use the car for anything other than commuting to work. I am on call one week in every four and when I get called out I have to sit like an idiot for hours before the thing starts and i can get home. Great fun at 3am.

gill
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  #12  
Old 8th June 2017, 08:58 PM
snapdragon snapdragon is offline
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You can put as high CCA as possible with out any detriment. AmpHours (Ah) and CCA can be higher but of course the voltage must be 12V. The earth straps are a good call.
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  #13  
Old 9th June 2017, 08:00 PM
erubus erubus is offline
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That's good news then, thanks. I stuck the 900 CCA battery back in it tonight before trying to start it. The engine was at the same temperature as it was last night when it needed jump started but with the 900 CCA battery span it over audibly quicker and it started no problem. I had the code reader plugged in and got a reading of 178 rpm before it fired, but again, as it reacts so slowly that figure cant be relied on. The next time I go to dundee I will try an immediate restart and see what happens. This is still the battery that came with the car though (brand new in October) and it's had this problem for roughly that length of time which was the reason the PO bought that battery.

Meantime I will check out the earth straps and have a look at how difficult its going to be to get the starter out. Might even add an extra earth strap direct from the starter just for fun. I will also check out what the most powerful battery is that I can get from my father. I'm sure he had batteries that size up to about 1200 CCA, anything more powerful would probably be getting into truck sized units.

Will keep you all posted.

gill
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  #14  
Old 10th June 2017, 07:31 AM
ainarssems ainarssems is offline
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You could buy something like this to carry with you just in case. http://www.ebay.co.uk/itm/18000mAh-C...38.m2548.l4275
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  #15  
Old 10th June 2017, 03:11 PM
erubus erubus is offline
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Quote:
Originally Posted by ainarssems View Post
You could buy something like this to carry with you just in case. http://www.ebay.co.uk/itm/18000mAh-C...38.m2548.l4275
Ive been carrying around a pair of spare charged batteries since i bought it but its touch and go whether they work. You usually seem to need the 14v of a running engine to jump it. My old series three land rover only puts out about 12.5 - 13v from its alternator and wont jump start the A8 when its playing up.

I just went out for a haircut and when I got back the engine was at 90 degrees so when I switched it off I went for an immediate restart and it span over pretty fast and caught almmost straight away. Leaving the car park from the barbers though it spun over for a few seconds before it caught, at about 65-70 degrees.
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  #16  
Old 12th June 2017, 05:48 PM
erubus erubus is offline
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Had the opportunity today to try starting the car after driving home form work, so running for approximately an hour. I'm delighted to say that it span over fast and started within a second or two.

I'm certainly not counting my chickens but perhaps all along it's been a combination of of a bad sensor and probably a worn starter motor. The combination of the new sensor and a more powerful battery together has made all the difference. Again, I'm not counting my chickens. Lets see how it gets on for the next couple of weeks before saying it's sorted(ish). Obviously I'm still going to have to look at the starter motor as the 850CCA should be more than enough to spin it over but with any luck I've bought some time. I'll keep you guys posted...

gill
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  #17  
Old 13th June 2017, 05:29 PM
erubus erubus is offline
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Scrub the above. Ttried starting it tonight avfter it had been sat for over an hour and nothing. Damn thing!
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  #18  
Old 13th June 2017, 09:37 PM
Mechcanico Lee Mechcanico Lee is offline
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The Bosch crank sensor you got for it was it from euro car parts by any chance ?
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  #19  
Old 13th June 2017, 10:12 PM
Mechcanico Lee Mechcanico Lee is offline
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Here's what I think you need to do , can you borrow a laptop with vcds or buy a cable .

When it does the fault plug in a see if any codes ....your generic code reader will not pick up all coding protocols.

If no codes , looking at the data blocks you need to look at cranking speed , camshaft speed, ....crankshaft /camshaft synchronisation yes/no


Make sure fuel rail pressure is there , fuel pressure will have to be over 250 bar before injection will commence .

A few things to look at .
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  #20  
Old 17th June 2017, 09:05 AM
erubus erubus is offline
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Agreed. I'm just wasting time and money now. As all the obvious faults are exhausted I will just need to get VCDS before I can get any useful information. Annoyingly thats why i took it to a garage with a good reputation advertising as over 100 years combined experience and Audi trained specialist technicians. I did this right at the start but as far as I can tell all they did was read the exisiting faults and clear them rather than try and diagnose the actual fault.

I dont kow anyone with VCDS who can do a proper check for me and I'm baulking somewhat at the cost of buying the genuine program. Think I might just have to go for it once my finances are in better order. The OH keeps booking holidays, so im constantly in a cycle of handing over vast sus of money! Anythign for a quiet life haha.

Has anyone used the cú30 VCDS programs you can get on the likes of ebay and amazon? Obviously copies but if they work well enough I'm happy to try them first.

To me it still seems like an engine speed thing. If you switch the car off then immediately go for a restart it starts up every time, leave it for a while and it doesn't. The OH will be home early on Monday so I can park it on the driveway and then try restarts every five minutes or so and make up a graph of time against cranking time and maybe cranking speed. Might give some useful insights but until I get some proper data from the car I'm p*ssing into the wind.

edit: The timing chain tensioners have started to rattle on most start ups now, especially when hot and there si a ticking noise on idle, so I suppose it could also be a crank/cam synchronisation problem. Can't see why a jump start would allow it to start if that were the case, same for fuel pressure.

gill

Last edited by erubus; 17th June 2017 at 09:08 AM.
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