Hydro carbon emissions by cars are big problem.
Unburned fuel as it evaporates releases hydrocarbons and in an effort to reduce these emissions cars started to be equipped with systems to catch these harmful fumes. Early carbed cars might just have a charcoal canister or EGR; pretty simple and no electronic control.
Cars with OBDII have an even more complicated spaghetti of vacuum lines, check valves, pressure sensors and solenoids, all controlled by the car’s ECU. These systems have built in self checking capability, which means that when one of the vehicles systems doesn’t meet the correct operating criteria. That little vengeful glowing orange silhouette of an engine or the words “Check Engine” find their time to shine.
My daily driver WRX lights up the check engine light every time after I fill it up, then drive the car and it hits a quarter of a tank. Somewhere in the time it takes to drain the tank to three quarter full, the car’s ECU does a self check of the EVAP system and it fails. It’s a P0457 code, which is an EVAP small leak/Gas cap loose. Trust me, that was the first thing that got changed.
With my current commute, the check engine light comes on after I reset it, about every two days. The quickest way to fix this would be to bring it to a shop with a smoke machine. The smoke machine pressurizes the EVAP system and a stream of smoke will spew out of where there is a leak. Simple right? Well a smoke machine cost easily a thousand dollars or paying a shop might cost me a hundred dollars to have it diagnosed. It also takes time out of my day because I’d need to take the car somewhere.
To the internet I go for answers.
Right now, as gearheads, we have access to nearly all the automotive information we could ever want on the internet. The disappearance of forums of forums and, really, Photobucket’s change to a paid service effectively killed a lot of useful threads.
Social media has made people lazy. We have all this information, but you need to work for it, research it. Instead, now it’s a Facebook group question. Since you don’t have to work as hard for the information and knowledge, it doesn’t feel as special or sacred.
I start searching forums, the trouble code pulls up lots of threads with lots of different answers to what it could be. I’m probably wasting my time, but I’m curious to how the system works and maybe, I can figure it out without smoke testing it.
I strongly suspect that since I live in the rust belt, the car needs a fuel filler neck. It’s not leaking fuel, but one of the evap lines on it could be rotted. It’s under a plastic cover, so a visual inspection isn’t that easy. Of course now that I’ve typed that, I should pull the cover off.
Regardless, I settled on the EVAP solenoid on top of the intake.
It was easy to reach, has a failure history of cracking and leaking, the vacuum lines to it often leak, and the plastic T-fittings break. It was worth a shot. I replaced the valve and the dried out hard vacuum lines with new silicone ones and a brass T-fitting.