sklatt36

Morning. For months now I have been struggling with diagnosing the problem with my 2015 Q7 Prestige S-Line. Random starting struggle. Tries to start but wont unless I pump the gas pedal. Other times it starts right up and is perfect. On drives at a stop it will start to have rev issues. The rpms will dip down and back up. Lately its been bad enough to where the car actually stalled at a stop light. Then with the starting issues, it took a bit to get it back running. However, if I put the car in park the rev issues don't usually happen. Or it will stop if I notice the revs dropping, and shift into park. The CEL will stay luminated for a week or so, then go off for a few days. I have a BueDriver scanner. ill attach the reports to this post.
I have now replaced both S1 02 sensors, and B1 MAP sensor. I also replaced the fuel filter just incase that was an issue. And just put in brand new spark plugs. I work on a lot of my cars, this one is beating me. Any possible help would be greatly appreciated.

Thank you in advanced.

Macksq5

Did you find a resolution to this problem?

sklatt36

High Pressure Fuel Pump. For the week that its been replaced, so far so good. No hiccups.

Macksq5

Thank you for responding, I can smell gas a little when driving, I replaced my 02 sensors and put in new fuel injectors all OEM, but I'm still getting codes for 02 sensors being bad P0136, P0156, and pump current open circuit P2237, P2240

Can I ask how you made the determination that it was the High-pressure fuel pump?

Macksq5

Also were you getting codes for running rich?

sklatt36

I took the car to a European repair auto shop. After a few hrs of diagnosing, that's what they determined. They said a big give away is if you can smell gas in the oil. It made my 02 codes go away so far as well.
Hopefully that helps.

Macksq5

Great, thank you for responding

sklatt36

Yes I was

Macksq5

I wanted to update this, I changed out the High-Pressure Fuel Pump and have driven the vehicle for 200 miles, with no issues, and no engine light, so thank you sklatt36 for sharing your results, The dealership wanted to change all 4 of my 02 sensors and I knew all 4 sensors could not go bad at the same time.

sklatt36

Glad it has worked out for you too. Wish I knew that's what It was before I changed out 3 sensors and the fuel filter. lol