Piston Slap: A Panther Love (EVAP) Purge?

Sam writes:

Dear Sajeev,

After reading TTAC for many, many years I succumbed and finally got me some panther love. It blows my mind that Ford can make such a well-balanced, corner-carving sedan and then never sell it to civilians. I traded my 2006 Mazda 3 for a 2006 Police Interceptor Crown Vic (170,000 miles). The aftermarket exhaust makes it growl and it parts the sea of entitled BMW drivers hogging the fast lane like a dream. Unfortunately, due to living in glorious urban hellscape that is Oakland, I have to pass smog regularly.

I have a check engine light code P0443. I replaced the evap. control module that was supposed to fix it and surprise, it didn’t. The internet says it could actually be my fuel cap. I replaced the gasket on the fuel cap and the check engine light is still on.

The next option seems to be to replace all the lines to my fuel system. This seems crazy, just because of a small vapor leak. This is not an expensive car (est. $1,500) and it was only meant to be a quick fling before I buy my Mazda CX-5 middle-aged nerdy dad car. Is this something I or a mechanic could fix for less than $500, or is this the death knell for an old police cruiser?

Sajeev replies:

Replace all the fuel lines? Who on earth told you that? There can be two sensors and inspect/replace all vacuum lines that look the least bit dry rotted, gooey, cracked, etc.

Sam answers:

I actually replaced both the solenoid and the canister purge sensor. I have not replaced the fuel tank pressure sensor. That might be the offending part. It looks like I have to drop the fuel tank to get to it which sounds like a pain in the ass, but it is worth a shot. It might be something I can have my mechanic do.

Can I just buy vacuum lines online? Those are the lines I thought would be difficult to replace. The one last thing I thought about changing is the charcoal vapor filter because it also takes forever to fill up the gas tank.

Sajeev concludes:

Ah-HA! You didn’t mention that filling up the tank takes forever!

Maybe you are also getting a P0445 code like this Panther owner did upon further inspection? Perhaps this thread shows the diagnostic tree you must branch out for? I’m not gonna guess: who knows if the vapor management valve (or whatever its called) failed or if you only have bad vacuum lines.

Therein lies the rub: paying someone for a proper diagnosis was a better idea than the unnecessary stress of throwing parts at a problem. If the vacuum lines pass muster, I would still enlist a proper mechanic for a proper assessment.

[Image: Shutterstock user Madcat_Madlove]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.