My '87 Escort GT was having problems with idle stability. The revs were ranging over 600 rpm and occasionally the car stalled. As an aside, the air conditioner wasn't really working. I just called the garage and asked if the car was ready, and if so what the problem was - no codes had come up in a previous checkup. Their resident EFI expert said that the Air conditioning unit module was faulty, which caused the AC to conk out, and that the unit had been sending out faulty signals to the EFI module which caused the idle fluctuations. I asked him if this could be the case even if the fluctuations occured when the AC was off and he replied it was. I will pick up the car in one hour and find out if he was on the ball, but the thought has crossed my mind that we will eventually reach the stage where: "Sorry sir, but your engine was backfiring because of that pebble caught in your tire tread." "Well sir, the pebble threw off the automatic wheel balancer which generated faulty signals to the engine control module." "No sir, when you brought the car in previously it was parked and that is why the engine only backfired when the wheels were in motion." "Well, I wouldn't call it a design flaw as all the controls for the onboard systems are housed in a single board which ran no codes and was functioning correctly. In the event that the board misfunctioned you would have noticed it immediately." "Well sir, the owner's manual does state that polyester clothing can build up a static charge on the steering wheel causing the cruise control module to malfunction." "Yes sir, that would account for the fact that the cruise control locked and could not be released at a speed of 130 MPH." "Yes sir, I understand how traumatic that might be. But rest assured that we have taken steps to resolve the matter. You will now find a grounding strap permanently located on the steering wheel." "Have a nice day too sir."
(From the "Rest" of RHF)