Now in the days of the Nude Hamster,
cymrullewes and
unixronin had two chariots, one of the making of Dodge, and one of the making of Mercedes. And it came to pass that the Mercedes did illuminate its Check Engine light, and begin to run most unpleasantly rough; whereupon
unixronin, lacking the mystical means to extract from the secret heart of the Mercedes its fault codes, took it unto the Mechanic of a local service station, saying unto him, "Lo, my chariot aileth. Canst thou read out the fault codes for me?"
And the mechanic did read out the codes, and did poke and prod at the engine, and did observe real-time mixture and other mysteries, and did pronounce, "Lo, it is a vacuum leak. It is causing the EGR valve to malfunction." And he did swap out an eight-inch piece of vacuum tube, and call the problem solved.
But this cure did not sit well with
unixronin, who believed it not, suspecting an ignition malfunction. For on this day, he had come to believe through repeated observation that this Mechanic did, in fact, attribute all engine problems of which he knew not the cause to vacuum leaks; and further,
unixronin did not believe that the nature of the misfiring was consistent with a vacuum leak, nor with an EGR valve problem; for it occurred only when the engine was both hot, and under load. And lo, the Mercedes continued to misfire when hot and under load, and indeed the misfiring became more severe, and did begin to occur sooner after starting the chariot, and did begin to occur even at idle once the engine was hot.
But
unixronin procured for himself an instrument for the reading out of the ODB-II data, and secured a manual on CD for the Mercedes; but the manual was not of use, containing no useful information, for it was not a manual of instruction on the servicing and assembly of the chariot, but rather one mostly prescribing repair and replacement guidelines. And
unixronin looked upon it, and found that it did inhale with great vigor, and was not useful.
Nevetheless,
unixronin persevered, and did find the location of the ignition coils beneath a cover atop the engine, and at length did discover the location of the third bolt hidden beneath the intake trunk, and expose the ignition. Then took he his xenon timing light, and used it to test the ignition and see unto which cylinders a spark was being delivered; but the Mercedes was obstinate, and would not misfire until
unixronin took it out for a fifteen minute drive, during which period it began indeed to misfire most mightily.
Thereupon
unixronin brought back the chariot, and reconnected his timing light, and observed that indeed, the ignition coil supplying spark to the second and third cylinders was producing less than half the number of sparks as the coil supplying the first and fourth cylinders.
Thus came he forth from the garage, brandishing his timing light and triumphantly proclaiming to one and all,
"Vacuum leak, my ass."