I went through the computer reset as instructed; turn on headlights, disconnect the negative battery cable, I left it disconnected all night. This morning, turned lights off and reattached negative cable. The reason I'm not sure it worked correctly is because my trip odometer and clock reset when I connected the battery cable but the programmed stations on my stock radio didn't change. This doesn't seem possible! I have always lost my stations when I disconnected the battery. The truck idled a little rough for a few minutes then smoothed out, it drives fine, just not sure if it reset correctly. I tried the reset because I had recently done an airbox mod and didn't reset the change.

 

I think you are all set, if the clock and the odometer reset. When I disconect my battery I allways have to reset the clock, but not the stations.

 

Greg Mc,

The reason why your stations didn't reset is because most newer car radios contain a "serial EEPROM" memory for storing the presets as well as the balance/fader/bass/treble if they are electronically controlled. A serial EEPROM is a nonvolatile memory device which means that it can retain its memory even when power (the battery in this case) is removed.

The radio clock is a different story. A serial EEPROM device has a limit to how many times it can be reprogrammed. Since a clock is updated very frequenty as time changes, the clock data cannot be stored in the serial EEPROM--it must be stored in RAM.

Why did you need to reset the ECU after your airbox mod? I installed a K&N FIPK Gen II and nowhere did it state that the ECU needed to be reset after installation.

 

RJ_Expy, thanks for the explanation, makes sense now. The reason I wanted to do the reset is because of a mileage decline. My truck is a 99 Reg. Cab Flareside 4.6. I've had the truck for about 3 months and my first mpg on the first two tanks was 15.7 and 15.2 with Exxon gas. I swapped the stock muffler for a glasspak but kept the stock tailpipe and on my next check mpg was 14.7 (no name gas)and the truck was alittle sluggish. Did reset and it ran alot better, then did the airbox mod a few weeks later. Truck runs great and has more power after the airbox mod but my last 2 tanks i've only gotten 13.3 (Amoco) and 13.25 (Exxon) mpg. Don't think it is engine compartment air because it has been cool since the airbox mod. After the last reset, the truck was driven really short distances only about 5 miles each trip. Thought I would do another reset and then drive the it work for a week which will give the computer a better mix of conditions and also include some highway driving. Maybe the mpg will come back up or maybe it is just winter gas.

 

When you turn the key for the first time after resetting the computer watch the guage needles, they will all go up all the way then back down to normal. This is how I tell, youre right the presets remain, puzzled me for the first time too.

 

So that is the reason the tach pegged when I turned the ignition this morning. I didn't notice the other guages. That is what I love about this board, you ask the question and someone always has the answer. Thanks guys.

 

Greg Mc,

The reduction in gas mileage can be caused by a number of factors. Oxygenated fuels used during the winter months can reduce mileage a bit, but so can a "heavier foot". After replacing the stock muffler and the air box, people tend to get a little heavier on the gas because of the great sound.

Also, consider that increased air flow will result in the ECU sending more fuel to maintain the proper air-to-fuel mixture ratio. Otherwise, an engine can run lean if there's too much air and not enough fuel. This is how an air box modification creates more power.

K&N and other air box manufacturers always claim better gas mileage, but that's not really the case unless you use a light foot.

Also, you shouldn't really need to reset your ECU. The stock ECU will learn and adapt over time to changes that you've made to the engine. That's what the OBD-II takes care of. OBD-II systems continually monitor multiple sensors and make adjustments accordingly to maintain proper emission and mileage levels.