rfmad

Thought we’d have some fun solving my ongoing mystery…
Quick summary of issues.

2007 A8L 85K miles has had zero issues until mid March

3 weeks ago problem was car would crank fine but would not start/fire

Read on here ( it was a Sunday) about resetting cluster so I disconnected battery and let sit for 30 minutes So I tried it and it worked. After that it would star if I let sit disconnected or if battery died ( which it did many time while cranking) 10-15 minutes later when I got jumped off it would start right up.

Went to dealer next day put car on Dealer computer got some sort of fuel vapor issue. However since i had dumped the codes by disconnecting the battery the dealer diagnosis may have been faulty.

Initially thought was a fuel issue so I replaced fuel filter.

Problem went away for a week or so (Who knows why at this point?) But eventually as some of you predicted problem returned.

Was then told dead battery had it checked seem fine.

Now all of a sudden while car is running... radio and other MMI functions start cutting off for a couple of seconds and then song starts back up playing again then cuts out again… happens every 20-30 secs. Then eventually MMI goes out and may or may not reboot itself.

Before this next step was going to be replacing fuel pumps but that doesn't explain MMI & radio issues.

Was told this AM most likely alternator was not charging battery and need new alternator. That made some sense until this AM after letting car sit 2 days with dead battery when I got jumped off and immediately drove dead battery to have alternator tested and battery which was dead had gained juice/power on trip to mechanic which meant alternator was charging.

Then told it was bad battery so I had dealer put in new battery this afternoon. Radio and MMI still cutting out after new battery installed(within minutes of newly installed Audi battery).

2 hours go by and just got it car still with new battery would crank(plenty of power) fine but no starting. So I disconnected battery and let car sit for 10 minutes and still would crank fine but no starting.

So I turn on key without cranking engine…then I turned off key and turned on a second time without cranking again and wait for 10 secs while systems boot up again and then cranked and it started right up.

Any ideas?

Important!!!!!
What has worked every time is letting car jump off after battery goes dead. Has worked everytime but only heaven or one of you knows why.

Im serious about the pay pal. 1st right diagnosis get $10 via pay pal. May take a few days to test out but Im good for it!

Please include pay pal email with responses. No this is not some sort of scam!

mishar

But it was solved in your previous tread. One about octane miracle.

Here is the winner:

rfmad

Would that affect MMI/radio while driving down the road ?

mishar

It would by killing your battery. Low battery causes many things on this cars to fail.

Bangerla

Could also be a bad fuel pump relay, they seem to have a fairly high failure rate on VW / Audi.

halik

MMI cutting out - you have a problem with the ground lead to the chassis. I would bet the issue is bad ground lead that makes things like injectors and coil packs cut out, same way your radio cuts out. Put a volt meter on your accessory 12v and see what it does when your radio is going out.

rfmad

Thanks where is this located on car?

halik

Which piece ? The ground lead should be near the battery and bolt into the chassis.

parkrog

How old is battery??? I have had battery's be intermittent and go direct short! Alternator might be struggling to keep up. If battery is over 5 years old start there, spend $150 or so first. Check for lose connections at battery area. Good Luck

tashakes

I still think this may be the issue. On my Benz it only happened when the engine was warm, but some info shows that it also happened on cold cars when the problem was not addressed quickly, kinda got worse with every start until it just would not start. Keep the $10 and donate it to a veteran organization.

Cheers