Question about a code.

[LaserSVT]

Let me just put this out there, I am a double ASE master tech and own my own shop. I specialize in Ford Modular but know my way around a 3800 car. Just got my 2000 SSEi and have thrown about $1300 in parts at it the last 24 hours fixing various things but nothing to due with the only code the car had. P1639.

Now I know P1639 is for the AC pressure sensor or FTP sensor. I disconnected the AC pressure switch (by the compressor) and found it to have a perfect 5V on it so that tells me the FTP sensor is OK. Tank level does read a little erratic but not sure how bad. empty was empty and $5 put it at a full tank. $70 latter and the tank was full and reads full but I have only put 33 miles on it so the needle has yet to move. According to my research the level sensor has nothing to do with that code anyway (it did have a high circuit code but cleared and stayed cleared) and I charged the AC today and now its functioning properly so that tells me the sensor is working properly as the compressor did not kick in until I had 10-12 OZ (weight) of R134a in it.
Now I have not gone to the sending unit to unplug the FTP sensor and test voltage because as I stated the AC switch is doing what it is supposed to do.

So here is my question, what the heck could it be? Could the AC pressure sensor still hurt that 5v signal even though it seems to be operating correctly?

Any help is appreciated.

[LaserSVT]

Never mind. I forgot to reset the code after charging the AC. I reset it now and the code has yet to come back.

[Zeik75]

YaaaaaaaYyyyyy simple fixes!!!!!!

[LaserSVT]

Dang, code came back. I guess I am just going to order the AC pressure sensor.

[LaserSVT]

Well heck, replaced the AC sensor and the tank pressure sensor and the code is still there. I read both sensors and they have their refrence voltage and are sending out a proper signal but for whatever reason, my ECM just still throws that code.
Not sure how the Bonneville factory computer is mounted but mine is velcroed to some kind of heat shield under the CAI. Gonna run a ground to its chassis and see if that does anything.

Also during the scan it showed my EVAP solenoid was shorted. That shouldn't have anything to do with the code I have but something else I have to look into I guess.

[LaserSVT]

DP

[Zeik75]

Ecm shouldn't matter stock it is in the plastic airbox.

[LaserSVT]

That's what I had thought. I also checked the EVAP valve and it is working properly. So..... dunno. Guess when I send my ECM to Intense for the tune-up that I will just have EVAP, EGR and O2 codes removed from the system. Thinking of getting a 3.5" pulley as well.

[Zeik75]

Yeah who knows the ecm may be a bit messed up from the PO, however the wiring may have also been hacked at some time. You could try ohming the wires before you get the codes taken out.