Sunday, March 8, 2009

Spark plugs: another easy way to fix serious problems

  • Changed spark plugs and spark plug wires (Bosch)
Sluggish pick-up, tractor sounds, bad fuel burning, and mis-firing. These are all things possibly caused by bad spark plugs. Not surprisingly, my car featured all these exciting quirks, and as a result had a zero to sixty of about a year, and started with the reliability of an old Dell laptop (think: say nice words and it may start). After changing the spark plugs and wires, I now have slightly better performance! Also, the car starts on the first turn of the key! And best of all, the engine sounds like a car engine again!! I wanted to go on to change the timing, but had cut myself enough just changing the plugs so I left it for another time (and performance was good enough for now).

I'm not going to go into the details of how to change a spark plug here (on this car, any idiot could change them), however you should note that the bolt is not the standard spark plug size bolt. In fact, it's quite a bit larger and I had to use an adjustable wrench to get them out. Also the reader should note that I didn't have to gap the spark plug, as the spark plugs can be bought with the right gap nowadays (I wish I knew that before buying the gapping tool...).

Most notably, the mis-firing you see in an earlier blog (flames coming out of the carburetor) has now stopped entirely. This is due to the fact the old spark plugs were very oily (see image of one of my spark plugs below). Over time the spark kept reducing in size (due to crap build-up) till the spark was so small if didn't ignite the fuel anymore, resulting in excess fuel at times. At that point the slightest spark set of an enormous explosion that partially went out the carburetor. That's what I think happened, if anyone has any other suggestions please let me know as I'm just guessing here.

According to Haynes, this could be due to worn bores/piston rings, or valve guides, and sometimes occurs during the running-in period of the car (though only temporarily). Considering I recently changed the valve cover gasket (though I doubt this has anything to do with it) and don't drive very often, I'm going to be optimistic and say this is a temporary problem that has now been corrected.

So there we have a simple way of improving performance: change your spark plugs and spark plug wires. Baby steps towards getting back to (better than) factory settings.

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