As I may have mentioned previously, my 1993 Subaru Impreza LS has a faulty throttle position sensor. I diagnosed it using a non-autoranging digital multimeter on the megohms setting. A better solution is to use an analog ohmmeter, or to follow the factory test procedure and connect a voltmeter to some of the pins on the ECU. So far so good. I ordered a cheap Delphi replacement part from autopartswarehouse.com, and the fun began.
The relevant part is a couple hundred bucks cheaper than the OE part, and apparently fits a slightly broader range of vehicles. This may or may not be incorrect; certainly it is different than the original, although it looks like it should work. Unfortunately, mine came damaged.
The problem, in fact, appears to be that they received a returned part and then sent it out to me without adequate care for the condition of the part. As the box that it arrived at my place in was in great condition, I know that it did not happen during transport between the shipper and myself. This part was definitely in the same condition when they placed it in a zip-lock bag, then put it into a cardboard box with a bunch of those inflated airbags. I didn't have to pay for the shipping, but this represents gross over-packaging as the box's volume is probably an order of magnitude greater than the part's box's. (Did I get that right?)
A throttle position sensor is an extremely simple device. In practice it is little different from the volume knob on an old-school (or just cheap) television or radio; There is a resistive piece which is usually circular or semicircular, and a switch to detect the idle position — and possibly one for the "wide open throttle" or WOT position. The OE part on my GC5 is encased in hard plastic, then potted in with epoxy. As such it is extremely protected from the elements and from any type of intrusion. The Delphi replacement part consists basically of a small metal plate to which the internals of the TPS are attached, and a plastic cover which goes over the part. I wouldn't even believe it was a valid replacement if not for the connector, which at least given a cursory examination appears to be the same as what's on the car.
The basic functional difference between one part and another is this: while the OE part is sealed, the replacement part's case only clips on with some weak little tabs and thus should really be sealed on by some other means (whether Delphi thinks so, or not - there's no documentation in here.) This would be only a minor annoyance, except that some of those pathetic little clips are broken. The box that the part comes in shows significant signs of abuse, but again the shipping box does not... leading us back to my former conclusion.
Today is Sunday, so I'll have to get back to the quest for satisfaction tomorrow. In the meantime I'm left with a stumble during acceleration and the following question in mind: where in California can I walk into a store and purchase Delphi auto parts?