I have a b20 in my 93 civic eg that runs terrible and extremely rich. Just noticed today that when I unplug my map nothing changes. I am not getting power or ground to any of the 3 wires at the map sensor. Does anyone have a wiring diagram or any tips on where to start looking besides tracing the wires? Thanks

 

I have checked pins D17 D19 and D21 coming straight out of the ECU for the map and I have nothing. . So bad ecu? I tried another ecu and same issue..

 

Do you have any check engine codes???

I don't think its a bad ECU you need to find where your break is for the MAP sensor wires. Check for continuity. Your going to need a multi meter and search how to test the Map signal. No map signal will cause your issues your having.

Also make sure you don't have the map and TPS plugs backwards, I know on B series vtec engines the Map and TPS have the same style plug and you can mistakenly put the wrong plug on the wrong sensor and have serious issues.

 

Thanks for the info. No they are not backwards I triple checked the wiring diagram. I started with proving the ecu. Pins D17, D19, D21. I am getting 12 volts power on all of them, but one is a ground so that's weird for 12v to come out of the ecm when one should be a ground.

I currently took my engine harness apart. No break in any wires. Going to the ecm harness next to trace.. will keep you posted.