Good day everyone,

I've recently been having some issues with my Q45. It started two weeks ago when I was on my way home from the doctor. I was doing about 30-40 mph and all of a sudden my car shut off. Electronics were still working, but motor had turned off, as well as my power steering and any other belt-driven functions. I pulled the car over to the median and tried to start it, no result. Went and hooked up my jumper pack to it and it started back up. It died once more on the way home, but this time I was able to restart it without the jump pack. I got it home and started doing research, and decided to work my way down the list. I checked the alternator and it turned out to be good, and the battery was reading 14.5-14.6 volts when the car was running. The car wouldn't start one morning, and it gave me a camshaft positions sensor code. I replaced the sensor and it started right up, just for it to die five minutes later. I checked the status of my negative battery cable, and it was undamaged and clean. I removed the air filter to see if it made any difference, and it didn't. I then unplugged the MAF when the car was running, and it made it run worse. I then pulled the Y-pipe off to check if I had clogged cats. The car struggled to start again, but this time it ran fine. I drove the car with no y-pipe the following day for around 40 minutes, and the car gave me no issue. As I was driving back home the next day, the car died again. I was able to restart it and drive it home, where it then refused to start again. I decided to replace the fuel filter next, and did so, determining that the fuel filter in the car looked to be original and had some dirt in it. The fuel pump worked great and could be heard and seen running. I then reattached my y-pipe and let the car run. The car then seemed to begin a re-learning process, and it would stutter during initial acceleration and enter a limp-mode whenever I floored it and tried to go above 3000 rpm. It felt like it cut fuel and the tachometer hovered around 3-4 thousand rpm. The FPCM would go from Low to High and then back to Low when it hit around 3000 rpm. I need this car back up and running reliably as soon as possible. What other items should I check? Is it worth sinking more money into this issue or do I have something seriously wrong?

Thank you.

Are you still getting the code for the camshaft position sensor? What is the # of the code (PXXX)?
You could have:
1) an issue with the CPS circuit
2)exhaust back pressure. When you were driving with the Y pipe removed, was the car running right, or not? Do you have a way to test the pressure at the upstream o2 sensor bung?