I have an 03 F150 FX4 5.4. I recently took off my stock air intake and replaced with a cold air intake. The manufacture said to disconnect the battery for 2 hrs to reset the ECU, so I did. Now the truck is sluggish and doesn't have the get up it used to. I guess its obviouse that the new intake is causing a problem. I checked for air leaks past the MAF sensor and there aren't any. Please help anyone.

 

First it does not take 2 hours to reboot the computer. 1minute is enough.
Second what are you looking for with the change?
The stock intake is already cold air intake.
A replacement won't add any power or fuel mileage.
Back to the computer reboot; you cleared all the tables back to factory setting so it has to learn all over again.
If there are no codes set run awhile to see if it improves otherwise return to the factory hardware and don't disconnect the battery.
It's not necessary.
Good luck.

 

Put the original intake back on....Reset the PCM.

 

^ what they said

 

Cold air intakes do not help with engine performance on modern vehicles. The manufacture has already placed the intake where it needs to be. I have learned this in college training and also researched it. I found out cold air intakes can in fact be a waste of money. When a battery is unplugged from a truck like your own has been unplugged it needs to go through a learning process as bluegrass and others have already stated.
When the battery is unplugged and plugged back in let the engine idle in park(neutral) for a minute or two so the engine can relearn itself.

If you want more power out of your engine first before anything else you should check/change spark plugs, CORRECT LY clean your mass air flow sensor with CRC mass air flow sensor cleaner, change your fuel filter, and not to mention finding/ repairing other performance hindering problems such as vacuum leaks.

 

Sometimes it depends on what hardware and design is used ahead of the mass air meter.
In a normal system the air meter samples a calibrated represenitive low percentage of the air flowing through it and is factory calibrated to the program for fuel injection vs RPM and load as indicated by the throttle position sensor.
If some hardware design alters this relationship through the mass air meter the drivability turns out altered and can cause a code to be set when the computer detects a shift of a fuel table out of design limits.
With rebooting the PCM in any manner a number of tables are cleared back to base values.
1. The cold start strategy has to be relearned.
...a. cold temp detection.
...b. idle speed and limits.
...c. engine load control from such sources as the alternator load recharging the battery after a cold start.
...d. power steering loads.
...e. A/C loads.
2. Hot starts relearned form sampling the coolant and intake air temps.
All the same as above but changes to match a hot start condition such as no high idle unless some load calls for small increases such as for A/C cycling, lighting loads etc..
All this means the Idle air controller is modulated full time to meet all 'idle' conditions as it's control table is continuously being changed by the PCM program input signals.
A near complete relearn can be accomplished by starting with a totally cold motor starting it to let run to fully hot.
Drive about 5 miles in the hot condition.
Stop the motor and do several hot restarts so it has these conditions to store and drive back..
There after this the colds and hot starts should be perfect if there are no faults in the system.
The fuel tables for long term are still being rebuilt from inputs from the short term tables and during driving in real time in varying temperatures and conditions as they average out.
The tables are always shifting to meet the conditions and even account for engine wear over time.
The computer...he was made pretty smart!
Good luck.