I just traded for a '92 DX Hatch with a B20Vtec Swap. It runs well, but the car has no Vtec and kinda bogs down at times. I've pulled the codes and I'm getting code 3 (Map Sensor) CEL. Any advise on how to diagnose this? I've noticed the car actually has 2 Map Sensors, 1 on the Firewall, and 2 on the top of the TB. I've got them both plugged in, and the on on the TB is connected to the harness coming out of the firewall, not the one running from the harness. If anyone can help, I'd apprectiate it immensely.

Daniel Sartin

 

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check the harness n see if wiring is all connected n not cut or missing.. also check your shock tower to where ur engine harness connects too.. i had a problem with the shock tower not having all 3 map sensors wires on there. so i rewired em directly frm map sensor to ecu n now the car runs perfectly fine with nomore cels

 

Should both the MAP Sensors be hooked up? I know the B-series is on the throttlebody, but there is also another on the firewall with the same connector, but different wire colors... Anyone know the voltage outputs of the sensor while running? The Yel/Grn has 5.0v while running but i don't know what wires to test for outputs and the ranges they should be in. Any idea's of whether the sensor is bad or ECU (Stock P28 is whats in there as I got it), or the wiring?

 

u should only have one map sensor the other one behind the tb should be the tps sensor n yes they should be both connected

 

There are actually 2 MAP Sensors. One is on the TB and the other is behind it on the firewall. Here's a pic of them.

 

ok sorry i forgot about that one

 

well on my b20v im only using the top map sensor on the tb not the fire wall one on a p28 as well no cel check to see if ur tps n map sensor plugs are backwards

 

The MAP wire color are:
Wht
Grn/Blu
Yel/Red

According to the Diagram I have, this is correct. Also The ECU is a virgin unchipped P28. Is this the source of my issue also?

 

im thinking that might have something to do with it cause im running a chipped one try n see if u can get ahold of one frm a friend or wat not swap em over n see if the issue would stop