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running cold and warm....

5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

running cold and warm....

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Old 01-30-2005, 06:04 PM
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90Mustangfan
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Default running cold and warm....

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?
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Old 01-30-2005, 07:32 PM
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88_5.0
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Default RE: running cold and warm....

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.
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Old 01-30-2005, 09:16 PM
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86HOGT
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Default RE: running cold and warm....

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.
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Old 01-30-2005, 09:48 PM
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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.
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Old 01-30-2005, 11:50 PM
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roundman
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Default RE: running cold and warm....

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.
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Old 01-31-2005, 09:03 PM
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90Mustangfan
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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?
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Old 02-01-2005, 09:25 AM
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Default RE: running cold and warm....

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.
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