IP Communications and Beyond

I've ranted before about a variety of automotive issues -- from the ridiculous cost of headlight changes to the mind-boggling complexity of today's computer/sensor-laden cars -- and I've got one more to add to the list: the problem with relying on computer-based diagnostic assessments of your car's condition.

First some background: I own a 2002 Audi A4, with about 51K miles on it. About a year into owning the car, an engine check light went on and I smelled burning rubber from the engine compartment. I brought it promptly to the dealer and had it serviced. Turned out a vacuum hose had melted (apparently all too common in VWs and Audi's) and the dealer replaced it, reset the on-board computer, and handed me back my keys saying, "You're all set!"

Problem is, the car never really felt right after that -- the Turbo-lag always seemed a bit too pronounced and the car never really accelerated as it should. Every time I brought it into the dealer for service, I'd complain about the performance and asked them to check it out, and every time I'd get a response saying "We hooked it up to the computer, and everything reads according to specifications."

A few months ago, the engine check light came on again, and this time I brought it to my local mechanic that I've come to regard as a genius. I no longer bring the car into the Audi dealer since my Audi bumper-to-bumper warranty has expired and I'm loathe to pay $160/hour for service -- and as I'll explain shortly, because I simply no longer trust the quality of the service the dealer provides.

The mechanic hooked it up to a diagnostic computer, and the printout stated that there was a vacuum leak somewhere in the system. A number of the vacuum hoses on the engine are sheathed in a nylon mesh that covers the rubber, and a visual inspection of the hoses found no problems, so he went to the next step of pumping a special kind of smoke into the system. Sure enough, he spotted a hose where smoke was puffing out of the nylon mesh -- and once he took it out noticed that the rubber under the nylon was brittle and cracked. He then took the next step of replacing all these hoses he could find in the car.

My car now runs like new -- no lag and no acceleration problems. I then related the issues I had been having -- for years -- with my car and the inability of the dealer to find any problems. The problem was the dealer's over-reliance on computer diagnostics, and that many problems aren't significant enough to trigger a fault in the system (since the computer is set to certain tolerances) but are serious enough to seriously impact performance. For four years I had been driving a car with damaged vacuum hoses (the melted one should have alerted the dealer to check them all), and my pleas to check the car out fell on deaf ears and eye's only interested in the computer printout.

So, the moral of this tale is when you are having performance issues with your car, and your service person tells you "everything checks out on the computer", don't accept this as "case closed". Find a mechanic who will think out of the circuit board, who will perform tests to get to the bottom of the problem and who knows the limitations of computer-based diagnostics.