View Full Version : A4 2.5 tdi poor starting

04-11-2010, 07:12 PM
Hi I`m new to the forum & have a question, I recently bought an a4 2.5 tdi quattro (52 plate) the problem is that if I leave the car for more than about 5 hours it`s difficult to start, the only way to start is to give it a bit of throttle & wait for it to catch & fire......resulting in lots of smoke from the exhaust.

maf has been changed along with glow plugs & i can`t see any leaks allowing air into the system......any ideas?:aargh4:

04-11-2010, 11:20 PM
I recommend you have it tested with vag-com to check the measuring blocks for the coolant temperature sensor.

14-11-2010, 06:41 PM
check the small rubber return hoses fitted between the injectors including the blanking plug on the last one, any pin ***** hole in these allows air in which lets the diesel slowly suck itself back into the tank, the longer you leave it before you try start it the more it has to suck the diesel back up the lines.....

14-11-2010, 07:47 PM
Thanks,,,,,I`ll check the pipes tomorrow as it`s getting quite annoying now.

07-06-2012, 07:26 PM
Cold start usually are related to bad fuel pump. There are some main faults related to fuel pump: hard to start when cold - mechanical fault; hard to start when hot - electric fault; engine stops when hot - electric fault; very hard to start cold/hot - mechanical fault. If car doesn't start at all - electric fault (electric unit PSG5) - dead transistor. I refurbish ~1000 pumps a year, so could tell really long story about V6 2.5 engines and faults :)

24-03-2015, 03:29 PM
Talk about rising a dead thread! :-)

It's like as asoon as I fix one fault in this car of mine, another crops up immediately! (Allroad C5 2005 2.5Tdi 180 horse)

In the last 3 weeks, I've replaced the front suspension airbags (again), the satnav antenna, booked in to remap the ecu to get rid of EGR light activation, repaired the wiring at the headlight unit, and cleared all the faults with vagcom...

And then last night and all today, the car is getting very difficult to start. Cold or hot. Had to turn on the starter for at least 6 seconds before it starts. Can't keep this up as it will burn out the starter. It's not a glow plugs problem, as the car is difficult to start when hot. Do I need VagCom again? I've done a fault code read and nothing showed up on a standard code reader.

Help! I'm losing my hair with the stress of keeping this beautiful car on the road!

You guys here have been a brilliant help in the past, so I'm hoping you can come to the rescue again!