I have a 1994 1.8l turbo Miata that is running on a SpeedyEFI plug and play ecu. I have run into a weird issue regarding a difference in readings between MAP (kpa) and Boost PSI. My car had started running lean at peak boost and when taking some data logs I saw a weird difference between MAP and Boost where the Boost psi read much higher than the MAP (kpa) reading:
As I understand it, 100kpa is roughly atmospheric pressure and anything above that is would be considered "Boost" pressure. So, according to this log I would have 74 kpa (174 kpa MAP - 100 kpa atmospheric pressure) of "Boost" pressure which is ~ 10.7 PSI when converted. I am more inclined to trust the MAP (the 10.7 PSI) reading since that is approximately what my wastegate is set at.
But, if somehow the Boost PSI reading is correct, that could explain the leaning out issue. The car could be making 15.5 PSI and if the MAP reading is low, then it would not be using the correct cell in the VE table. However, since both pressure readings come from the same source, I don't think this theory is correct.
Nothing has changed for me firmware wise, or hardware wise since I had a normal reading (MAP kpa reading = Boost PSI reading). Is this a Tuner Studio issue/setting? Or could something within my ECU have gone bad? The boost gauge I have on my tuner studio dashboard was showing the 15.5 PSI in boost as well. I am going to go over the line that runes from the intake manifold and the ecu itself but any input would be greatly appreciated. Data log and tune attached.