Notes from Windward: #70


Improving My Mechanical Skills

Opalyn learns to decode
on-board computer readings

     Thanksgiving week I headed north to spend some quality time with my bio-family near Seattle. Friday morning, full of turkey and good vibes, I headed south for Portland, but before I'd gone very far the "check engine" light came on. I pulled over to call home to Windward and, since I was nearby, to check with the shop that used to do my mechanic work back when I was commuting to Evergreen State College in Olympia.

     Truth be told, had the "check engine" light not come on, I would have continued to Portland never knowing that anything was wrong. The car sounded fine and the engine was not running rough. Understandably, the mechanic wanted me to come into the shop so they could run a diagnostic for "only" $98.00. The consensus from Windward was that I should head on south to Portland, and we'd deal with it when I got home.

     Well, I'm pleased to report that I made it to Portland safely and enjoyed a rich evening of games and friendly conversation. The next morning I invested in an oil change and some general maintenance before driving back to Windward. The shop that did my oil change would run the same diagnostic tests for only $20 but they could not do any repair work.

     My faithful Rav4 ran smoothly enough, but there was definitely something wrong since over all I burned an extra half-tank of gas getting from Seattle to Windward, via Portland.

hooking up the OBDII code reader

     Arriving safely back at Windward, I dug out our On Board Diagnostic II (OBDII) trouble code reader and hooked it up. The code reader was a spendy tool we purchased last year to troubleshoot some issues with another computer-controlled vehicle.

     One of the great benefits of living in community is that not every single person needs their own washing machine or code reader--by sharing tools, instruments and skills we're able to do lots of things we'd otherwise have to hire someone else to do for us. Whether it's tuning an engine or tuning a piano, it's great to know that we've got the right tools to do the job right.

     Anyway, I hooked up the computer and six codes came up--actually three codes came up twice each--all of which decoded to having to do with an engine misfire. Since an engine misfire code can be any one (or more) of about a dozen problems, I decided to start small and replaced my spark plugs. They were well over-due for replacement anyway, and inspecting the old plugs would give us more information about what was going on.

the three clean burning plugs

      As I removed each plug, I was careful to check it's condition. Three had a white ashy substance on them that showed they were burning properly, and one was fouled with carbon. Now we knew which cylinder was having a problem.

      The fouled plug had a wet, greasy look to it, so I took in inside and laid it on top of the woodstove to warm up. If the warm plug retained it's geasey look, that wouldn't be good since it would indicate that oil was getting into the cylinder and fouling the plug. I'm pleased to report that the plug quickly dried off leaving a dull residue of black soot. That indicated that the fault probably wasn't internal to the cylinder. Good news.

the soot fouled plug

     I reset the computer and went for a test drive. I didn't even make it a mile before the misfire codes returned. The next least-expensive step was to change out the spark plug wires. With some elbow grease and convincing, I replaced the wires--removing one at a time and replacing it with a new wire before moving on to the next. That way I was sure to connect the right port on the coil to the right spark plug chamber making sure that the firing order remained correct. A key part of repairing something is making sure that you don't introduce new problems.

one of the old spark plug wires

     With the computer reset and the code reader attached we set out for Mt Hood to play in the snow and pickup supplies. The check engine light did come back on but the misfire code did not return. Apparently the catalytic converter needed some time to adjust to the newer components because the code specified that the cc was operating below optimum. About 100 miles of driving and I reset the computer again and so far no codes turned up.

     If you're interested in looking up the codes for your vehicle, check out the OBDII Trouble Code website: choose your vehicle make, or scroll down to see generic codes

     Another option is the OBDII website.

Notes From Windward - Index - Vol. 70