the Walnut Diary

Last night in a snowstorm I drove Ruby behind a pair of snowplows for about fifteen miles at speeds ranging from 33 to 47 km/hr.  The engine didn’t miss a beat.

Two weeks ago I had bitten the bullet and bought $611.00 CDN worth of Porsche coils from Mark’s Motors in Ottawa and installed them.  Had I tried to make do with the deteriorating coils I had bought two years ago from Amazon.ca, I might not have made it home under the damp, claustrophobic conditions.

Asian knock-off coils seemed to work adequately at constant, relatively high speeds, but if I slowed down for traffic, one or another of them would misfire until I had the car back up to speed.  The big problem in diagnosis was that it takes a 2% deterioration of spark for the car’s computer to set off the check engine light, thereby allowing me to track the error code to the correct cylinder for a repair.  A coil would spend about a month teasing me before becoming bad enough to allow me to identify it.

This greatly reduced the enjoyment of driving Ruby.

Then P0307 flashed on the code reader. #7 had failed outright in Athens, and I barely made it the twenty miles home because the oxygen sensor shuts down the fuel supply to a whole bank of cylinders on the V8 to protect itself when a cylinder misfires.  When I removed the coil, it smelled like the inside of a burned-out computer.  #7 is easy to switch, so I dropped in another Asian coil.  I had a box of them on the bench from a warranty settlement from the Amazon vendor.  Experience showed that half of them work, for a period not to exceed two years.

With the new coil Ruby started right up and ran normally.  After she was well warmed up, the slight miss recurred.  It wasn’t the bad coil which had failed.  It was another one.

That was the last straw.  When I complained about the Asian coils on the Porsche blog, the only comment I received was from the moderator, who wrote words to the effect that Cayenne owners have learned a long time ago not to use that product.  In some batches none of the cheap coils would actually work.

Ruby has not been an expensive vehicle to maintain over the last 2 1/2 years, and with the new OEM coils she’s twice the car to drive.