My 8 MR leans out when accelerating. Brand new sensor for the AFR gauge, brand new upstream O2 sensor, doesn’t seem to be any boost leaks, already fixed a leak on the throttle
body. Idle AFR is perfect. AFR is perfect when cruising. When I accelerate my AEM gauge leans out and reads - - -. I’m guessing it has something to do with fuel supply. No service engine light. How should I troubleshoot this?

 

How does the car drive while the gauge reads "---"? If i am not mistaken, the gauge only reads to 20, if its leaner than that, i dont think the engine would actually run. Maybe the AEM wideband sensor has failed? If the engine does run rough and you feel the gauge is being accurate, then I would park it and check base fuel pressure with a pressure gauge, then pressure during load. I do not know the specs maybe someone else does ( im sure the specs are listed somewhere on this forum) but at idle my guess should be around 50 psi maybe a little less.

*EDIT* found this for base fuel pressure
[size=16px]Approx 38.5 psi base pressure with the vacuum line disconnected from the FPR at idle. If you are adding an adjustable FPR, most guys set it at 43-43.5 psi base pressure at idle with the vacuum line disconnected.


So call it 40 PSI and add 1PSI for even 1PSI of boost you are running. [/size]