I bought this car used with 85K on it from a friends uncle, who swears there was nothing wrong with the car. Last November I r\the CEL lite up and immediately went to Advanced Auto to get it read. The first code said there was misfire in cylinders 1 and 3 and there waS A p1451 code. I did a tune up with wires, plugs and spark pack which resolved the first two codes I was getting. But the P1451 is the one that's driving me crazy. I replaced the evap solenoid on the firewall but still have the p1451. Someone suggested replacing the vent solenoid that's connected to the charcoal box under the trunk, which I did. I also replaced the gas cap. Since those are all brand new and I still have the p1451 some one suggested that the PCM might be bad. Before I spend the $200 for the PCM does anyone know how or if I can test the pcm to make sure it's not working and needs to be replaced? Thank in advance for your assistance.

 

You are replacing parts without knowing if they are defective . The code denotes a malfunction in the system and that requires a thorough check of all power, grounds and connections too!

 

Let me elaborate on what's been done so far. I've checked that there is 12 volts going to the purge solenoid on the charcoal box under the trunk with 38.2 ohms reistance. I also checked the purge solenoid and it has 12 volts and the same resistance. They both appear to be open since I'm able to blow air through both sides of either solenoid. I traced the wires from the vent solenoid and the purge solenoid back to the pcm to make sure there was 12 volts going into the pcm. I attempted to wiggle the wires to see if maybe there was a loose connection but I could not cause a voltage drop in either wire no matter how much i tried to wiggle those connectors. I then made my own intermediate connector to see if while the solenoid was in line there was a voltage fluctuation, but I saw a solid 12 volts all the time. I checked fuse #28 and it appeard to be fine but just to be on the safe side I changed it out with another 15 amp fuse. I thought I did a good job of trouble shooting but I guess I missed something and thus why I came to this forum to ask questions. Thanks for your assistance.

 

There is a fuel tank pressure sensor mounted either on the top of the tank or in the vapor line between the tank and the charcoal canister.
It is difficult or nearly impossible to check out these evap systems without a scan tool.
A few things you can try are disconnect the battery for at least 1/2 hour and reconnect it.

Make sure all the lines are clear and open for air and fuel vapors to pass.

The PCM does provide the grounds for the various solenoids and valves to work.

Make sure there is at least between 15 and 85 % fuel in the tank or the monitors will not be able to run.

You may have to have someone with a bidirectional scan tool run the tests and checks needed to pin down the problem.

 

Excuse me for being ignorant here but i thought all scan tolls were bidirectional and since this is the first ford product I have ever owned, why are they so friggin hard to diagnose. I have two GM cars, a 2003 malibu and a 2004 cavalier both with over 135k and when the cel comes on my scan tools tells me exactly what's wrong. And by having a bidirectionak tools how would that assist in diagnosis ? Please explain further because i thought all the scan tools did was read the errors that the on board computer found. I thought I read the user manual for the scan tool. So what you're telling me is that my scan tool can run diagnostics on the PCM and flush out all the problems that I'm having with this evap system ? Or are you telling me that it's to break down and take it to a mechanic . Thanks for your assistance

 

Your manual for the scan tool should tell you how to use it to check the evap components. The bidirectional features allow you to run tests on the various components and get the results as to how well they are working. You should be able to energize certain solenoids and get information returned to you as to whether they are working as required. As far as a scan tool telling you exactly what is wrong is partly correct, but you need to know how to use it , how the system is supposed to work and know when the results are wrong.

 

So I connected the scanner and did the evap test and found two PIDs that failed but it's not telling me which ones are failing. It give me test $2a and $2b and these two are fialing out of a possible 19. I connected it to my wifes 2003 Malibu and my daughters 2000 cavalier and it allows me to see all the components for the evap system and do a test to each one. But with the Taurus it only gives me a list of 19 but no node names. Is this normal or do I really have a problem with this car?? Thanks

 

John, the best suggestion I can offer at this time is for you to invest in a manual that explains how Ford's system functions. And add to that , there are some differences with each model too lengthy to try to explain here.

 

chilton's or the actual Ford shop manual ?