Ford Coil Pack issues
So I had planned to move my daughter tonight, but a week or so back my old Ford started acting up, which I drive about 3 times a month. A few years back I bought a scanner that I can hook up to my laptop and log most of the sensor activity on the engine, transmission, and ABS system. However, like most computer related stuff, things improve over time. So my old ford (1999 model) was having a misfire on a cylinder. The computer on the 99 won't log which one is having misfires until they reach a certain threshold, usually around 3%, however the computer will react and shut down fuel supply when it reaches a smaller threshold, in my case it was around 1.3%.
So when the vehicle computer senses that there is sufficient misfire to warrant reaction, which I mentioned, it checks around every 5 seconds, it will shut off fuel supply to said cylinder for 30 seconds to keep damage from happening to the catalytic system. Well, though the computer is trying to help, it won't throw the code to show which cylinder is having the issue until it reaches that previously mentioned 3% threshold.
So I had spent about $100 for the Ford ODB license to be able to diagnose just this sort of issue, but turns out that the scantool software can only do what the vehicle manufacturer logs. What I ended up spending 2 hours trying to diagnose I was actually able to do with the free software that comes with the scantool that I bought. That software (ODBWiz) allowed some low level monitoring of the sensors, refereed to as "Mode 6" or "$06" The trick is that it doesn't log, but you can refresh and capture a snapshot of what is happening with the engine. So as I mentioned, I had to try to capture the issue while the misfires were happening, which weren't shown while the cylinder was disabled for 30 seconds by the truck's computer, so I had a 5 second window to capture which cylinder was misfiring when the trucks computer did allow the cylinder to fire. Once I understood this concept, I got the information captured.
Now why does the misfire happen? Three things, lack of fuel (bad injector or issue with injector), bad spark plug, or bad coil. In my case, the spark plugs are getting old. It's the second set as I've got about 200k on the truck, so I need to do a plug change. However, as the plugs get worn, the voltage required to jump the gap on the plug increases. The coil pack adjusts for this, but if there is a defect in the coil pack, such as a pin hole or crack, the spark will jump through the defect and ground to the engine block causing the misfire as it won't make it to the gap in the spark plug.
While this is not related to woodworking, I hope that my experience helps someone else. And if I have to relate it to woodworking, I stepped through my dry rotted wood trailer deck tonight while moving my daughter and this will relate to an upcoming thread on me putting a new deck on the trailer.
To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault