Poor starting issue

[veneto rs2]

Hi all!

Major work done on my ADU in the last month:
New fuel flter
New fuel pump
New spark plugs
New PAS
New coils
All new plugs n connectors

All the above from Audi so everything OEM

Bought from 034Motorsport five new injectors RS2 replica (the white ones)

http://www.034motorsport.com/engine-components-audi-i5-20vt-rs2-replica-injector-set-p-369.html

They quoted the injectors to be plug n play but the retainers grooves are not suitable for the original clips,but eventually I had that sorted.

If I leave the car for the night, when I switch on in the morning I don't have anymore the prompt starting I was use to have, I must crank up fro three four second and then I have a bad start bubbling a bit then running smooth as ever.
No problem at all on hot or short stay stops.
No problem on power delivery, the car it's smooth as velvet and pushes good and hard, zero VAG faults, consumption it's the best since I own the car (1997)
In few words the only problem it's the morning starting.

I guess somehow the fuel system it's loosing pressure or one of the new injectors it's leaking?
Anyone confirms my idea? Or can be some other issue?

Thanks

Stefano

[prj]

Check your spark plugs.
Make sure they are not white...

I would not be so sure that those 034 replica injectors have the same injector dead time as the original ones. It's actually very unlikely that they do.
That can cause all sorts of issues...

Among a few other things bad starting can be caused by G4/G40/G28 pulses not lining up or wrong injector latency compensation in the ECU, thus giving too much or not enough fuel.

[S2central.net]

Sounds to me the fuel rail is not holding pressure like it should. There is a test I need to hunt out here... there is some kind of valve in the fuel system / pump that ensures the rail hold onto some pressure so that you don't have to wait for the pump to prime the whole system.

Wondering if someone messed up when they renewed fuel pump or filter ?????

Let me find the test.

[prj]

Very fair point. The issue can also be with fuel not getting there.

[S2central.net]

OK - here we go...

You need a means to activate fuel pump for this test - you could just remove the G40 / Hall plug and crank the engine over.
You also need a fuel pressure gauge fitted to the fuel feed line.

1 - Disconnect the vacuum / boost line from the fuel pressure regulator

2 - Activate the fuel pump (cranking engine over)... you should see ~4bar fuel pressure

3 - Turn off fuel pump and the fuel pressure should drop no lower than ~3.5bar

[veneto rs2]

Thanks for the replies guys and for the testing procedures Paul.

I forgot to mention that I changed (persoanlly) the fuel pump and filter before the PAS coils injectors plugs job.

Before that the RS2 started at the first cranking up turn, that's why I point out the injectors to be the issue.

I will try the holding pressure procedure anyway and if it's fine I will swap over the old injectors to see what's happen.

Thanks again!


Stefano