Hello Folks. 2 weeks ago I had a stage 2 Roush installed (by Ford dealer) on my 14 mustang (very pleased with performance). Since then it's been in the shop 3 times for the P0451 code. So far they have replaced the evap purge valve, fuel tank pressure sensor and some fuel line. Now they are saying they have to call Ford to diagnose the problem and possibly re-prog my computer with Ford original (really?!?! this happens and I'm going to be pissed beyond belief, retards). Is there anything else other than these repairs or the tank exhaust hose on the passenger side? I've searched hi-and-lo on the Internet and I've only found references to that one tank hose on passenger side and a fuel cap (being a 14 there's no gas cap).

 

sometimes cars are hard to fix, this is (im guessing) why you dont fix cars. let them work on it, nobody on the web is gonna fix it for you. if they cant get it fixed, try another dealer

 

You are correct jwogg. I am not an ASE mechanic. Professionals as they are should possess a certain level of troubleshooting skills, blindly replacing parts anyone can do. I do however enjoy working on it when it's not warranty stuff like this. I'll post back if they resolve the issue in case anyone else experiences the same with this type setup. Nice constructive reply, appreciate the feedback.

 

sometimes systems and components will test good using all known methods of testing them. for instance the evap system may not hold vacuum thus setting the code, but will hold pressure when smoke tested, and pass the smoke test. i have seen this several times. at that point, all one can do is start replacing parts till they fix the problem and it passes the monitor. this is the reality of troubleshooting vehicles, the test that has been developed will not always diagnose the concern you have.

 

http://repairpal.com/OBD-II-Code-P0451

The very last item states that if everything checks out ok then the problem itself could lie in the PCM...thus the PCM would need to be reprogrammed by Ford.

Maybe something corrupted or got written incorrectly during the tune phase.

 

Quick update for everyone. I was able to pick my car up yesterday. The issue lay with the original installer of the supercharger. They incorrectly installed the coolant temp harness. You know I guess I should have went with my first suspicion. My fan was constantly running from engine start to key off. Me never having a Roush before assumed that was normal operation. Anywho they billed the original installer and that installer approved the charges. I'm assuming when they say coolant, they mean the air charge temperature wiring which is connected to the PCM harness. The mechanic said he went through the install docs and when he got to the one step found it.