90Mustangfan

when I first start my car and drive for like 3-5min, the car runs great and feels like it has more power, more snappiness. But after the car warms up and has been running for like a hour the car feels like it lost a bit of power, not as crisp as when I first start it. Any Ideas why its doesnt runs as good as when its warmed up?

88_5.0

because when the engine is cold the metal is contracted which means less resistance in the combustion chamber for the pistons. Just wait until it gets warm out and when you start it and when you drive it you wont see much of a diff.

86HOGT

Are you serious? A warm engine is at the same temperature whether it's summer or winter.

I know what you're talking about 90MustangFan, my car feels that same way. See, when the engine is cold and in "open-loop" The engine runs on preset fuel delivery until it's at a certain temperature, then when it's in "closed-loop" then the computer loks at the 02 sensors and other sensors to determine the proper fuel mixture. It has also "learned" what your sensors operating range is also. These variables along with Ford's conservative programming for fuel mileage is the reason for the spunky feeling in the morning.

90Mustangfan

How can I change that so it always runs like its cold? Because I like when it cold it has a snappier punch and pulls harder in the gears.

roundman

best way to get around this problem is to buy a chip and install it on the ECU. they will definitely pick up the performance across the entire rpm range, at least the Hypertech one I got years ago sure did.

90Mustangfan

Do the hyper tech chips work good on manuals? I thought they were just for changing shift points? would I benefit from the hypertech chip/power programer?

roundman

all I can say is the Hypertech chip I bought improved the performance of my AOD car across the entire rpm band in addition to WOT operation. and the AOD is not shifted electronically by the ECU. the factory computer settings are very conservative and they leave a lot of HP and performance not available unless you change the fuel and timing maps in the computer and the only way to do this on the older EEC IV ECU like yours is to add on a chip.