Cryorayne

I have an 04 A8 that will start the 1st time in the morning or when it has been sitting. When I run errands and have to get in and out is when I am having problems. When it's hot I can put the key in, turn it, and nothing. No sounds, no starter, no anything, no errors or lights either. The radio and A/C will turn on and I have power. If I let the car sit for a little it starts right up no issues. This only happens when the vehicle has been running and it is hot outside. It was fine all winter with no issues.

This morning it started right up and I drove the kids to school. Got out and walked them in to class and it started no problem when I left. Then I went to get fuel and when I turned the key there was a 5 second delay before it started and then the EPC light came on.

Jack88

Crankshaft position sensor tends to be the culprit for this one. Search for previous posts on it, there have been many!

Mister Bally

Crankshaft position sensor symptom is the engine cranks, but will not start. Starter times out after 10 seconds.

Your symptom sounds like your starter solenoid is going bad. A fun repair job on the D3's with BFM V8 engines.

Cryorayne

a_very_naudi_guy

My vehicle does this at random from time to time; turning the ignition to engine on and it does nothing. I take the key out, place it back in, it starts right up. Doesn't seem to matter if cold or hot outside, or warmed up engine or not. Seems to be random in fact. Not sure if I'm not paying attention to a symptom or what, but it's been doing this for a while. Not nearly as bad as yours, however, with it not turning on. I can only recommend removing the key all the way, putting it back in, turning it maybe with foot on the brake, etc. Keep cycling. And get a Vag-com VCDS plugged in and see what's up. With that being said, I'm not sure what codes Mister Bally's / Jack88's comments would throw, but something to look at?

dvs_dave

BizarrEftersmak

I haven't been able to rule out everything else but my A8 -04 have from time to time refused to start and today when i was picking up the wife it really refused!
I tried everything, rocked it if the solenoid had caught on the flywheel, rolled it with and without gear in - automatic - and nothing, just some clicking.
Until after about 10 minutes, when it suddenly started right up.

When i got it home and parked it i tried again and three times in a row it started like clockwork.
I'm guessing it's just that time to replace the starter and not think about it anymore.

BTW, anyone knows about flange sizes? I checked my usual pages and some starters have 82,5 mm flange while some other have 77...so how do i know which is correct for my BFM engine?

ltooz_a6_a8_q7

If you're sure about the starter, I would test with a momentary switch to confirm before doing the hard work. Sometimes, it's the ignition that doesn't switch on correctly.
When the car failed to start when hot, brought me back to my other cars starter, when the engine is hot, the oil deposit on the terminals became liquid and make the connection more resistance with electrical signals.
Cheers,
Louis