Pre-96 vehicles had what is known as OBD I aka on board diagnostics I. Post 96 Vehicles have OBD II.
They became easier to diagnose after 96 as all the connectors are now uniform as well as technical allocations. Before, like yours, each manufacture had their own way of doing things and made it very cumbersome.
Anyways, when you disconnect the battery, the computer loses it's memory and needs to be driven to re-learn it's data stream values so it can make necessary adjustments. When it finds the problem you have it will throw the light again. Sometimes the computer can use a "default"value for an input that is out of whack. An input would be a sensor for example the tell the computer what it sees, the computer makes an adjustment to fuel/air mix and the change is the result of the output. So there may or may not be codes stored in the computer. Best bet is to have it checked.
For what it matters, have heard of a fuel pressure regulator cuasing your condition as well as a computer that is grounding the EGR valve Too long, in which case the computer would need replacement.
Friday, April 6th, 2007 AT 7:18 PM