Thursday, January 29, 2009
Now that you know the lesson I learned at the end of the story, let's skip back to the beginning. It was a cold, wintery day here in Salem as I was driving around town. Despite my usual lead-foot ways, I was driving more gently than normal since my car was still warming up (and makes unhappy noises until fully warm.)
As I turned a corner I saw a green light just waiting for me to make it through. I gave the car some gas and, rather than springing into action, the engine hesitated and then surged ahead, accompanied rather suddenly by the warm, friendly glow of the "Check Engine" light.
Not good. Nothing can stress me out faster than car problems.
Nevertheless, I went about my day until I had a chance to do some quick internet research. You should know, dear reader, that I'm a pretty terrible mechanic. I never have the right tools, I know little about engines, and I never seem to fix things quite right on the first try. But, circumstances being what they are, I was looking for any way that this could be very inexpensive to fix.
Somewhere on the internet I came across a tip that said, "Oh, just disconnect the battery. It'll reset the computer and the light will come on again if it's a serious problem." This sounded easy enough to do. I also came across another tip that pointed out that Autozone will read your check engine light code for free. Free is good, so I noted this for future usage as well.
I went out to my car (I wasn't home, by the way) and quickly disconnected the battery. I waited thirty seconds, plugged it in, then started my car. I was quite happy to see that the check engine light was off, but dismayed to see my car idling oddly. Not having much of a choice about it, I started driving home.
About five blocks later, my car hesitated again and the check engine light started staring at me. Remembering hint #2, I turned my car around and drove over to Autozone, which I'd just passed. My car stalled. I restarted it and drove up to the storefront, walked inside, and was promptly greeted by the most amazingly helpful person ever to walk the planet. (At least, in the context of this story.)
He grabbed his little diagnostic tool, went out to my car, and read the diagnostic code for the light. He then went back inside and gave me a printout of the diagnostic code (P304), what it meant ("cylinder four is misfiring"), and probable causes for the error. We then talked it over it determined that changing the spark plugs might fix the problem, and was the only possible solution that wouldn't require a mechanic and a couple hundred dollars in labor and parts. He sold me a set of spark plugs, a spark plug adapter, and showed me where the spark plugs were on my car and how to access them. It was easy. It was so easy, in fact, that after the transaction I moved my car to sit in front of the next business over and quickly changed spark plug number four in the dark.
I then drove the car home, though it was still idling very inconsistently.
The next morning I quickly changed the other three spark plugs and started driving around. Despite the strange idling, the car was otherwise running fine. No hesitations at all. Then I remembered that the last time my car was idling in this fashion was after I'd put a new battery in it. Huh.
It appears that the computer that controls my car holds bits of information about how the engine runs in memory that gets cleared when the battery is disconnected. I speculate that it has to re-figure out how to make the engine idle properly every time it's been cleared, which is why my car is running better and better after every warm-cold cycle.
Now, with the check engine light off and my car idling fine, I'm going to say that I have won this small mechanical battle. For less than $20 and with a lot of help from Autozone, it seems that I have beaten the check engine light. Now I just wish I hadn't disconnected the battery.