Help…. s3 8p won’t start after stalling earlier

[Davill9]

hi guys,

I was driving round a slip road earlier and car just misfired and stopped completely.
Just got the car home…

have 2 faults still showing

fuel too low and
Camshaft position sensor

I have changed hpfp to a new one I have here and no change.
I then checked mvb 103 & 106 and my pressure is about 5 bar on low side and 5 bar on high side.
Filter is about 2k old

any reason why the hpfp would not have the usual 50bar on key turn ???

could a faulty cam pos sensor stop HP fuel ?
surely the hpfp is mechanical ?

 

[Davill9]

Got all these first scan but battery was already starting to go flat by then

But on the power connected, it’s had low voltage faults cleared and is coming up with static camshaft sensor and low fuel ones still and they won’t clear.
When I changed hpfp, releasing the pressure at valve, the rail pressure went straight down to 1bar so readings are accurate and once fitted & primed , went straight back to 5-5.5bar same as low pressure side.

so seems definitely not getting fuel but this surely can’t be a camshaft sensor as cranking would build up pressure surely ??

 

[nluk100]

Have you replaced the FPR valve as these can fail over time (although I've not seen them prevent the car from starting)?

 

[Davill9]

Have you replaced the FPR valve as these can fail over time (although I've not seen them prevent the car from starting)?

Hi mate, do you mean the one on fuel rail under inlet or the return one inside of the fuel filter ?
Fuel filter is a few months old if that… fuel pressure regulator has never been changed by me as it is having rs4 one when unicorn does the next mapping for me- only thing pretty much not changed on engine now.

 

[Davill9]

Do you know if the canmshaft sensor cuts the fuel to hpfp or could a fuelling issue etc have triggered camshaft sensor by excessive cranking after car cut out.

I’m getting 5.5v at the cps connector

can’t really test sensor itself without replacing

something is stopping fuel from building up to the usual 50bar at high pressure side.
Surely as they have no return to tank, there would still be a significant difference between fuel rail and low pressure side even if a regulator had gone… maybe not enough to start but viewable in data

I’m wondering if like other makes, you pull the camshaft sensor to crank engine without it firing up for priming oil pump after replacing etc but it cuts fuelling that’s y they only crank when unplugged.
eg. The ej20 Impreza engine.

does anyone know what happens if u unplug the cps and try to start the tfsi ?

 

[nluk100]

Hi mate, do you mean the one on fuel rail under inlet or the return one inside of the fuel filter ?
Fuel filter is a few months old if that… fuel pressure regulator has never been changed by me as it is having rs4 one when unicorn does the next mapping for me- only thing pretty much not changed on engine now.

The one on the fuel rail - you can fit the RS4 one before the map goes on as it won't make any difference with the std map, however the std items are known to fail, so I'd fit it, especially if you already have it.

 

[Keram]

Are camshafts turning at all?
If timing belt broke then you can get similar errors.

 

[samuelh_888]

Cam position sensor, replace fprv at the same time.