Originally posted by suicideride93:
Can you alleterate on step 4 a little more
You mean "elaborate", not alliterate.
The TBI is, for the most part, a speed-density fuel injection system that uses "look up" tables stored in a chip. The engines sensors (TPS, throttle position sensor), IAT (air inlet temp), CTS (coolant temp sensor) and MAP (manifold absolute pressure) all the the inputs that "tell" the computer (the ECM) if you are trying to drive at constant speed, accelerate, or deccelerate. The ECM (the engine computer) takes these inputs and decides how much fuel to be added to the injectors (which really means for how long the injectors are pulsed to be OPEN and admit fuel).
The lookup tables in the chip are set at the factory, to match to a 350 cid engine (for the LO5), or to match a 305 engine (for the LO3), or to match a 262 v6 engine (LB4, yes it was an option during 89-93 model years). The chip also "knows" if the engine is the regular passenger car LO5 (used in Roadmasters, Caprices, Custom Cruisers or Cad Fleetwoods) OR if it's the police Caprice LO5 (which had 25 more hp than the regular LO5).
BUT you have altered the engine. You're changing the cam, you're probably using headers + duals, you might have ported the heads. The engine breathes much better than before, so the fuel maps (the look up tables I mentioned) set by the factory in the EPROM chip are now all wrong. So you need a custom chip to suit the changes you have made.
That's more than I wanted to write about it, and the fact that you asked means you didn't know. So you need to do some reading, especially here:
DIY EPROM forum
The DIY (do it yourself) EPROM (erasable programmable memory) forum has several stickies at the top of the main page -- you need to read through them.
The TBI forum also has several stickies that are worth reading.