I don't see why it matters that its a 2004/2.3. That does not matter whatsoever. It could be any vehicle that is MAF metered.

What you typed above is that the engine CAN'T compensate. From the wording you have above I think you meant to type CAN compensate.

The engine does not compensate for anything. It is just a bunch of moving parts. The computer and sensors are what do any adjusting needed.

How the system works (more or less)

Imagine you are an air molecule. You are drawn into the filter and you go past the MAF sensor. The MAF sensor "feels" how coldly you pass by, and it the change in voltage across the MAF is related to how "coldly" it feels as you go by. The computer then see's this voltage, and looks at the MAF calibration to say "OK, this .634 volts I am seeing means that 4 cubic feet per minute of air is flowing in" This air then goes into the manifold and at the same time the computer says "OK, since I know I'm getting 4 cubic feet of air right now, I need to check out the fuel map and look up how much fuel should go with that much air, at this rpm and this much engine load. The computer gives that spray of the injector (say 1.5 squirts per second or whatever) into the ports, it mixes with the 4 cubic feet of air and the plugs burn it when it gets into the cylinder. The computer is then all proud of itself, because it's calculated the right amount of air and fuel for the most efficient mix for mileage and the environment. After the exhaust stroke the fumes go past the first HEGO (the oxygen sensor) and it says "OK, I better check and see how the engine is running". It measures the oxygen content to see how closely it is running to 14.7, which is the perfect ratio. (Called stoich) Lets say for some reason, it wasn't quite perfect and the result was actually 14.0 instead of 14.7. This would be running rich. The computer would say "Oh crap, It's running richer than expected, so instead of putting 1.5 squirts of fuel when I see 4 cubic feet of air, lets only do 1.2 squirts next time. The cycle continues and the oxygen sensors read back "hey, this time I'm reading 15.2, so its too lean, I want it to be 14.7" - try only squirting 1.35 squirts of fuel instead" The computer will keep switching back and forth around stoich. If it has to increase the fuel map by lets say for the sake of example 10%, your fuel trim would be +10%. If it reduced it by 5%, your fuel trim would be -5%. This is called "CLOSE LOOP FUEL CONTROL"

Now lets say your done cruising around like this and you are in a race. You floor the gas wide open (WOT) The computer says "oh boy, I'm going to be dealing with alot of load here. Since I don't want to damage the engine by running too lean when things start going crazy, I'm going to just use the open loop tune where I spray fuel depending solely on a set map that works based on the engines load, and MAF readings" - In other words, It's going to be running richer than 14.7 on purpose, to keep things rich because we don't want spots in the combustion chamber that might be any leaner than 14.7. This is called OPEN LOOP FUEL CONTROL. In open loop fuel control the ECU totally ignores the feedback from the oxygen sensors (HEGO) and just looks at the predefined map that Ford put in when you bought your truck.

Think about what I've said. If your MAF isn't reading right, and the computer is in open-loop then how will the computer do any reactionary adjustments when you are in open loop? Most engine-boo-boo's happen when in open loop, under high load, and at high rpm. When you add a monster turbocharger like I have it is a recipe for destruction unless things are tuned right. It can be really destructive on an naturally aspirated engine also, because what you end up doing is running lean, which causes the fuel/air mixture to explode before its supposed to, causing the spark to throw the cylinder down while it still is on its way up (well in extreme cases anyways). More realistically things will burn very hot and your pistons may burn up, or you can crack a valve.

The reason why your computer is throwing a code is because its trying to protect you. The computer is figuring out that its adjusting the fuel trims too much and it shouldn't need too. I think with this information you can understand your answer to your question by yourself.



The only thing to do with the light is to put black tape so that you wont see it.... Any comments?

Thanks[/QUOTE]

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