I have been struggling with a map sensor problem on my b18b1 ls in a 94 eg cx. The only code im throwing is 3 for the map sensor. I tested for volts at the sensor on all 3 wires got nothing according to the pgm-fi troubleshooting guide for map sensors.

I then tested the wires at the ecu per the trouble shooting code and got got approx. 4.5volts on d17 d19 d21 (should it be 3 volts??). The trouble shooting guide said to look for misconnections in the wires to the map sensor.

I found no wiring issues, so I wired the sensor directly from the ecu to the map sensor with some spare wire. It fixed the d19 to yellow with red sensor issues becuase it shows 5 volts.

When I test white (+) and green/white(-) i get no volts even with it being wired directly.

I have also tried 3 different map sensors and 3 ecu's ( two p75's and 1 stock p05).

I would be extremely thankful for any help this issue is driving me freakin crazy.

 

Sounds like a bad ECU.

 

damn so all 3 ecu are bad?

 

Did you try all three ECUs after running three new MAP sensor wires?

 

yea 2 p75's and one p05, and changed 3 map sensors, all with the same result with direct wiring

yellow/ red running directly to d19

green/white directly to d21

white directly to d17

When I test with a volt meter white (+) and green/white(-) even directly wired still nothing. I haven't wired anything permanent until I know it is fixed, they are just twisted

Yellow/ red (+) to a body ground gets 5 v.

I did not volt test all 3 ecu's but the one I did test got 4.5 not 3v at d17 d19 d21

The only other thing I know to try is the sensor plug itself, which I have another to try

 

bump

 

I get 3v white, 5v other. My white wire was separated at the ecu so map wasn't working. Could just be a wiring issue.

Is white supposed to be 3v or 5?