engine start problem

[A8 Owner]

Hi, well since it went into the garage a cpl of weeks go, i have had nothing but problems with my car.
Here is the latest one.
When car is warm and you stop her.
If you turn her off and back on after a cpl of mins she will start as normal.
If tho you stop her and try after 5mins, its a different thing. It turns over just wont catch for a very long time.

Left 1.30 hrs it it starts a bit easyer.

Start in the morning starts like normal

The garage had the car back. It did it the night i dropped it off with them.
They then started work on it next day. Guess what they couldnt get it to do it. they put laptop on it, no codes show up.

What they did find is tho, the battery had 13v on it at the back. up front only 8v So took it to a battery company and agreed there was a problem with battery. So now had that changed, Flys over. didnt cure problem tho, as first start up wouldnt catch for along time (10-15 sec's)

So now i took some video clips
first clip is the car been started after 20min from getting battery




second clip about 2hr after coming home



Now as all the problems since they had it, have been in the area they were working. Front Pass wheel side.

reading forums have it down to.........
coolant sensor
evap emmision control
air flow meter
crank position sensor
cam position sensor
o2 sensor
throttle sensor
and the garage one is injector dripping.

Your views please

[Conan_the_Librarian]

If the battery is giving 13v but up front you get less, check the earth lead from engine to chassis and neutral lead from battery to chassis for poor contact. I changed a battery, alternator and starter motor before I found it was the engine earth lead had corroded. Good wire brushing of each end, refit and lots of petroleum jelly and boom!

[A8 Owner]

Thanks for info Mike. Well went to Steve's unit and used his ramp sssshhhhh.
Met his mate there who offered to help me. We found the power problem was Nr front on driver side under the car.

Right would the crank sensor been faulty show on vcd?
As from looking around on forum, seems other had same sort of thing. Theres turned out to be crank sensor.

Just incase no one has pressed the pics above there video's of it trying to start.

[RanjS8]

The battery power maybe an issue .....but that would normaly cause an issue starting from cold or cause efficient running issues....

Your issue is restarting when hot.....that is a classic case of the coolant temperature sensor problem....

change that and you will be fine.

[A8 Owner]

Just done some searching on here. Seems if its coolant temperature sensor you get some light on dash, aswell as something shows on vcd as fault code. i dont have anything.

[A8 Owner]

Well this has now been sorted. Changed crank and temp sender, didnt work.
Then looked into injectors dripping.
To cut a long story short,
Turned out to be LPG reducer leaking.

All fixed