Hi all
I've posted about my S4's numerous issues before and I have since gotten it started and it starts consistently, however, I am having even more issue than I did before (go figure). The main issue I'm having now is it runs very rich, making the cats glow and making so little power that popping the headlights almost stalls it out. Obviously not ideal for street driving or passing an inspection and, after several weeks of diagnosis and research, I am completely stumped, so I now ask for your help in maybe finding some answers or if anyone has dealt with and fixed this kind of issue.
So the symptoms I'm experiencing; the fuel pressure measured before the injectors with the key on is around 45 psi, obviously outside of the ~29-38 listed in the fsm. The fuel system also does not currently hold pressure without the fuel pump running, dropping down to 0 in a matter of seconds. One of the two previous owners had wired the fuel pump to always run directly from the battery when the key is on (something I plan to return to stock but that isn't priority with current issues), so that might contribute to the pressure being too high? I admit to being a noob here.
What I've tried so far:
I've tried three different fuel pressure regulators; the one that came with the car, a oem style BOSCH unit I got off ebay (new old stock I think), and a brand new regulator from RockAuto. None of these three made any changes to the issues. In addition to the FPR, I've also replaced the fuel pump. One of the previous owners had replaced to stock one with an aftermarket unit that's rated higher than whats listed in the fsm, so I got one also from RockAuto that is closer to factory spec. This also did not change the situation. I've tried disconnecting the return line at the rats nest and at the FPR to rule out any blockages after the FPR that would raise fuel pressure, letting it dump into a bucket. Still 45 psi. To diagnose the issue with holding fuel pressure, I clamped off the return line and ran the pump for a few seconds. Pressure held very high like I'd expect, and dropped of to zero as soon as I released the clamp.
All of these diagnostics point me towards a bad FPR but it seems statistically unlikely that I have three bum FPRs, two of them fresh from the box. I am willing to bite the bullet and get an OEM one from Atkins if that's the direction I'm going first but I want to exhaust all other options first. It may be a case of buy once cry once.
As I've said before, I'm a complete noob to rotaries (and project cars for that mater) so any help or diagnostic tips would be greatly appreciated. I can provide any more details if needed, Thanks for reading my very long (and a little ranty) post.