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Originally Posted by cmd
I have a 2003 H2 and have noticed that the acceleration is not consistant to where you put your foot into the pedal. The truck does not have much mid range, you put the pedal down and down and it will kick down a gear eventually, however does not seem right, no codes have come up and it has run this way for some time, and as i said it is not consistant. At a set of lights there is no hesistation on take off, lots of pickup, only when under load for a period of time during travel.
Any ideas would be appreciated, i have been thinking fuel? maybe a regulator?.
Thanks
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I think I know what you are saying. You need to understand how an ECM map works to be able to understand why it does this. The load placed up on the vehicle affects Manifold Absolute Pressure (MAP) which affects the which timing tables are used within your ECM. The more load that is placed on the vehicle, the lower the timing will be. It is designed this way to prevent detonation.
Different things can affect MAP such as wind pressure, towing, vehicle weight, outside air temp and humdity, etc.
Hope this helps...
BTW, adding a programmer can help overcome some of this. However, please note that most canned programmer packages (not custom mapping) only make changes to the upper throttle positions and this is why they make the claim that they do not affect mileage etc.