hillpc

Good point. The fuel pump changeout can be easily messed up, leaving the jet pump mechanisms not working. These move fuel from the left side to the right side of the tank, where the pump can pick it up. Otherwise the right side of the tank can run out of fuel even though there's fuel in the left side. Pouring fuel into the filler neck will temporarily fill the cup at the fuel pump.

How hard is it to put a pressure gage in the fuel rail? This seems like the bottom line for troubleshooting fuel supply up to the injectors. Or is there a pressure transmitter there already that could be read using VAGCOM?

160 Holland Ave.

My gas tank ia on half tank. When the car is at operating temp. It fires right up. But after sitting several hours it gets worse to start. Tomorrow I'll be dropping it off to my mechanic

Avant1522

I had a problem where if my car was completely cold or warmed up, it would start, but anything in between and it would crank until the battery died. Talked to my Audi Guru, asked in the temp sensor ever reads some ridiculous number like -150 degrees, popped on Vag-Com and sure enough, every few times it would read some ridiculous number. $10 later and some scalded hands (wait for engine to cool off before changing) Problem solved. It was the sensor at the back under the intake piping. IDK if those are your exact symptoms but easy and cheep to check off


EDIT: This Problem started gradually with hard starts and then got worse and worse.

twentysevenlitres

The temp sensor is consistent with my understanding of fuel injection and the temp sensors have a reputation for failure.
When cold, the engine will start with timing fully retarded.
As it warns up the engine will run at ever more advanced timing.
For a hot start the ECU will run the timing advanced, increasing it the hotter it gets.

So a cold engine with a faulty temp sensor may run fully advanced timing making the car very hard to start indeed.

In short well worth swapping out as Avant1522 suggests.

160 Holland Ave.

Thanks 27liters. Yes you are correct. Picked my car today from my mechanic. He said it was the temp. Sensor he replaced it and started my car up the next morning n it fired right up. Cut it off waited several hours n it fired right up. So hopefully it was it. Thank yo all for the help guys. I really appreciate it.