Troubling trouble codes
Back to the saga of my wife’s wayward car with the intermittent stalling problem. You will be happy to know (okay, maybe you’re not happy, but I am) that it’s finally fixed. I had to do what I’ve told a million people to do, and leave the car at the shop until the problem reoccurred. It would not happen during test drives with scanners connected. It only happened when I drove it with no test equipment. I left it at the shop, and they kept it idling all day, and it finally shut off. This time the scanner showed a code for a faulty crankshaft sensor. Until then, the sensor had not failed long enough to set a code, but it had failed long enough to kill the engine several times. That was the first time any code had been shown.
You probably know by now that we rely on those computer codes (a lot) to help diagnose failures these days. The codes are not the complete diagnosis, but lacking any codes, it becomes extremely difficult, even with tens of thousands of dollars in sophisticated test equipment, to diagnose these machines. If the problem is also intermittent, which happens a lot, the difficulty is magnified. It’s impossible to rush it, so patience is required, even from me. We cannot make it happen any faster for the public than we can for me, or more importantly for my wife. I know the adage about the shoemaker’s kids going barefoot, but believe me, when her car breaks, Momma doesn’t walk, barefoot or otherwise. She takes my truck.
Speaking of sagas, and of computer codes, leads me to mention once again, the most common reason for the “check engine” light to come on. Many, many times it is caused by a vacuum leak in the Evaporative Emissions System. The EES is a huge network of hoses, switches, valves, pumps, check-valves, pressure sensors and relays, and a canister filled with activated charcoal. These things are stashed away in hidden compartments and nooks and crannies all over the car. Their purpose is to capture the fumes from the gas tank and either burn them in the engine or store them until the engine can burn them. The gas tank is pressurized and that pressure is monitored by sensors. If the pressure drops for any reason, even a loose gas cap, the amber “check engine” light will be set. You are now polluting the air with gas fumes, and global warming will be your fault if you don’t have it fixed, (according to the EPA).
This failure causes no problems with the way the car drives, and it will not make you break down, so some people ignore it for years unless they smell the fumes. When we’re all hip-deep in seawater, you can yell at those people for causing it. In a state with no emission inspections, you can ignore the light if you want to, but we can’t make the light stay off without fixing the leak. It is not an easy system to work on. The engineers hid this equipment in inaccessible places, apparently not expecting it to be such a common complaint, but it is. Sometimes pumps fail to pressurize the tank, sometimes valves stick, relays fail, rubber hoses crack and leak, or sensors fail. One of the ways we have to locate the leaks is to inject a harmless smoke into the tank and look for where it comes out a real challenge on a windy day or a very small leak. It takes time to track down the leaks or faulty parts, so again, patience is required. I hear it’s a virtue, but I have little first-hand knowledge of that subject.