2001 A4 1.8t AWM Avant Quattro.

Have to crank the **** out of it to start it when cold. Acts as though it's rich/fouling plugs. I push the accelerator pedal down to the floor, which shuts off the fuel injectors, and that clears out the intake and the engine can start.

I've replaced crank, cam, coolant sensors. New spark plugs and coils. New PCV related vacuum hoses and components. New fuel injectors and fuel pressure regulator. New fuel pump and filter about a year or so ago, don't suspect an issue there, no issue with fuel delivery because the engine is fouling plugs (take a plug out and it's wet).

No engine codes except for the occasional miss during cold start (not the issue, just a symptom). Once started the engine runs fine. I can even shut the engine off before it's fully warmed up and then start it again without trouble. If I let the car sit for about 20 minutes it starts being kind of hard to start again. If I let it get fully cold I have to crank it for about 10 times or more before it will start...I can reduce the amount of time I need to crank by pushing the gas pedal down to the floor to clear out the system...but it still takes to long to start.

At this point I'm wondering if the combination valve for the secondary air pump (some people call it the EGR valve) might not be opening when the engine is starting? Could that cause the engine not to start?

 

Figure out the issue...fuel pump producing to much fuel pressure causing the injectors to foul the plugs on cold start...and engine runs rich at idle. Fuel pressure should be around 50psi at the rail, my car was close to 70psi. This is to much pressure for the FPR and the vacuum control can't compensate. I'm changing the fuel pump because it's obvious the check valve in it is stuck open.

 

Replaced the fuel pump and the fuel pressure is still to high, even after having a new fuel pressure regulator. It's a 4 bar pressure regulator. 4 bar is what was in it before I changed the fuel pressure regulator. It's a BWD fuel pressure regulator....has anyone ever had problems with this brand fuel pressure regulator?

 

It's not the fuel pressure regulator. The FPR holds pressure in the rail. Even with the new pump in the tank, it bleeds off pressure right away after shutting the engine down. This means the fuel is going back through the supply like back into the fuel tank. Either the new fuel pump check valve is also stuck open (likely not) or I have a leak somewhere between where the fuel like connects to the pump and where it exits the fuel pump assembly cap. Has anyone ever had problems with leaks on the fuel line inside the gas tank?

 

I took the fuel tank cover off and connected a hose to the pump outlet on the cover. I blew into the hose and I could hear a bit of a hiss around where the hose between the pump and the cover connects. Whoever owned this car before me put arrow clamps on the fuel line instead of proper fuel injection type band camps. So it's pretty clear the fuel line inside the fuel tank was weeping and that's likely why there was an immediate fuel pressure drop when shutting the car down...also explains a hard start. I ordered a new in tank fuel line and proper hose clamps. This should take care of the fuel pressure bleed off.....still need to figure out the high fuel pressure thing. If I still have high fuel pressure after fixing the leak I may go with an adjustable fuel pressure regulator.