A4 Intermittently Not Starting

[dvespa]

Hi All,

I was hoping that I get get some additional clues for you all.

Over the past few months my Audi A4 has fails to start intermittently . When I turn the key it tries to start chug chug chug chug ( no start) try again straight away it starts....however the EPC light comes up. SO I turn it off and start again...starts no worries.

This has happened once every few weeks.

My thoughts were the Batt. Whilst the car is off the Batt is at 12.4V..........whilst turning the key it drop to approx 11V and then whilst running it is approx 14.4V. is this ok?

Three weeks ago I noticed it was failing to start every 3 days or so. So I have now asked the wife to ensure that prior to turning the car off ensure everything is off. i.e climate control / lights / wipers anything./radio

Since then the car has started every time....no worries at all...it has been great.........so I am assuming that its related to the power the climate control is drawing when attempting to start the car.

Is this an issue with the Batt or Alternator? someone mentioned a relay (I'm not sure how to test that)? and a friend mentioned current draw (again not sure how to test)

If anyone has any other suggestion that would be great.

Cheers

David/

 

[aragorn]

If its winding over then i doubt its a battery issue.

You say it only drops to 11v when cranking, which is pretty decent tbh. Some batteries will drop to 8 or 9v and still happily start the car.

12.4v at rest and 14.4v with the engine running are both perfectly normal values for a car battery/charging system.

I'd start with a fault code scan, find out whats bringing on the EPC light.

Also, when you turn the key to "crank" the ignition switch shuts off all the auxiliary electrics like the Climate control, Wipers, lights etc, to ensure maximum power is available to start the engine.

 

[Arrkon]

EPC is usually Throttle Body or Acc pedal related. It may be that your TB is on the way out / Sticking. but as per aragorns post, a vagcom scan should point you in the right direction.