Poor warm starting S2 ABY

[driftin jo]

how are your spark plugs ?

[hermanio]

they are new, i think im going to place an extra check valve in the fuel line and see if that works

[driftin jo]

they are new, i think im going to place an extra check valve in the fuel line and see if that works

If you have run the pump before starting and there was no difference It's not going to be the check valve. The check valve is only there to stop fuel from flowing back to the tank so when the pump starts it makes pressure in the system immediately.
If you run the pump for a few seconds before you start it even without a check valve it would be up to pressure so it can't be that.

[hermanio]

my thoughts are that it can only be a fuel related problem, but all ideas are welcome

[hermanio]

does there always have to be fuel pressure on the fuel rail ?, this morning, with the engine cold i pulled my fuel pressure regulator out of the fuel rail and there was no pressure on the rail. is this normal ? when i put the FPR back, the engine started good so thats strange isnt it ?

[rs200]

does there always have to be fuel pressure on the fuel rail ?, this morning, with the engine cold i pulled my fuel pressure regulator out of the fuel rail and there was no pressure on the rail. is this normal ? when i put the FPR back, the engine started good so thats strange isnt it ?

no this is not strange, this is normal. you thing that car will start without FPR?
what FPR do? fuel came from fuel pump and FPR make pressure, without them all fuel go back in tank. there must be fuel pressure in fuel rail and FPR make that possible.
try to change your FPR with another which is 100% ok.

[rs200]

same symptoms I had on dad's A8 2.8 30V , and the problem was some blue 4pin tem. switch . something like MFTS on 20v engine. but I don't believe that MFTS can do that problem!

[hermanio]

ok, but you schould have some fuel pressure in the fuel line, not ?

[prj]

Yes, you should.

If you pull out the fuel pump fuse and let the car use up the fuel and stall, when you put the fuse back and try to crank it will take a long time for it to start.

Although in your case, I simply think that the problem is with one of the sensors.
You need to check if there is spark.

I am betting that Jamo was correct, and that one of the sensors is not giving a good signal, or one of the wires has high resistance.
You can temporarily tap one of the ignition coil connectors and monitor it.

It is controlled via ground... so check if the ECU is giving the ground for the coil to fire.
If not it is not a fuel or FPR or whatever related issue, it's a problem with one of the sensor signals.

[hermanio]

can i measure ground with a multimeter via the plug thats goes on the POS ? one pin on the engine and the other pin in the connector ?

[prj]

It should be connected probably, so tap off it, put a wire into the connector and then yes, measure.
Make sure you are measuring the GROUND though, as otherwise the results could be quite shocking.

[hermanio]

just tryed that, when i start i measure ground. but when it was a faulty sensor, why dont i have the problem when the engine is hot and i restart within 5 minutes ? strange problem, but am i the only one with this problem because i have it on my s2 and rs2..

[prj]

So do you have spark when it's cranking?
And how many revolutions does the engine make? It's not an instant-on old diesel, you know. Worst case it has to make 2 revolutions.

[hermanio]

i know how an s2 suppost to start. see the video i posted, thats not normal. in the video i give a little trottle when the engine start, when i dont do that the engine almost stalls for 5 seconds

[Bowlerwell]

I get this sometimes...
Usually it starts in 1/2 a crank, but sometimes it takes quite a few, and another 2-3 seconds to burble up to normal idle.