95LsTiCGM Posted June 12, 2020 Report Share Posted June 12, 2020 Hey guys I recently installed my Gx4 plug and play into my swapped v4 sti. Upon initial set up I found that my map sensor (stock) would not calibrate. So I checked all my wiring, I'm getting about 5.2v to the feed, I've got a good ground, and my signal wire ohms out to less than .03 ohms. The factory sensor was reading 10.9 psi key on engine off, so I went ahead and ordered the link 3 bar map. After installing I can see that my map sensor reading is now 12.9-13 psi where barometetric is at 14.5, again no calibration. The only thing I can see is that signal voltage read on PC link from the map sensor is coming in at 1.41v, where measured at the sensor and at the harness side of the pcm pin is 1.62v. Any thoughts or advice would be greatly appreciated! Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 12, 2020 Report Share Posted June 12, 2020 31 minutes ago, 95LsTiCGM said: The only thing I can see is that signal voltage read on PC link from the map sensor is coming in at 1.41v, where measured at the sensor and at the harness side of the pcm pin is 1.62v. I guess that could mean either your meter is reading different than the ECU, or there is a 0.2V ground offset somewhere. Can you measure voltage at ecu also, between pin 71 (sensor ground) and 67 (AN V 1). Compare to the voltage you measure between gnd and sig at the map sensor. Quote Link to comment Share on other sites More sharing options...
95LsTiCGM Posted June 13, 2020 Author Report Share Posted June 13, 2020 Okay thank you, I'll check tomorrow and get back to you! Quote Link to comment Share on other sites More sharing options...
95LsTiCGM Posted June 13, 2020 Author Report Share Posted June 13, 2020 Update: measured voltage between pin 67 and 72 (sensor ground in the pin out) and I get 1.42v, if I measure between pin 67 and direct chassis ground I get 1.6v. Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 13, 2020 Report Share Posted June 13, 2020 (note MAP sensor ground is 71, not 72). Ok, so it seams somehow your MAP sensor might be grounded to the chassis (maybe its ground wire has been spliced in to something else along the way? . It should be grounded to Pin 71 according to the wiring diagram I have. If you unplug the ecu and MAP, do you have good continuity from MAP ground to pin 71? Are they the same colour wires both ends? Pin71 should also be the ground for the TPS and coolant temp sensor, can you confirm they have continuity back to pin 71 and to the MAP ground also. Quote Link to comment Share on other sites More sharing options...
95LsTiCGM Posted June 13, 2020 Author Report Share Posted June 13, 2020 Yes you're correct, my map wiring had been modified in the past, if connected to pin 71 I got it to calibrate and read correctly! Pin 72 was control systems ground so that worked for a reading as well but I will repair my wiring and go from there. Thank you for the quick response! Quote Link to comment Share on other sites More sharing options...
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