Question about 2003 GMC Sierra 1500

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GMC Sierra 1500 power loss at 1/2 throttle and above

Last week the pressure fitting on the heater core failed. ....in traffic. It emptied the cooling system completely, and I had to drive about a half mile before traffic would allow me to merge to pull over in a shopping center to diagnose what happened. during this half mile drive, the temperature rose to over 260* indicated, and the engine went into a protect mode/power reduction. I was able to clamp the failed circuit of the the cooling sys. to get to the dealer and get the part, but once changed, and fixed, it will run fine, and then reduce power. anything above 1/2 throttle and you can feel it lose power- let the gas off real slow, and you will actually accelerate a bit. I also noted the tem will rise and fall abruptly on my gauge, so this is a kind of "red flag" to me.. I also replaced the thermostat today thinking the excessive heat may have affected the temp. range of the existing thermostat. reset the ecu, (left the batt disconnected while I changed the thermostat) And now the service engine light is off, but the power reduction is still evident at above 1/2 throttle position. I thought it might be the tps, but what are the odds that it would go out at the same time as the coolant fitting bursting?

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  • exciter900rr Oct 27, 2008

    actually, believe it or not, my knock sensor was the culprit-  all that steam and water shooting over the intake.....  yup filled the knock galleys and poof! p033 or whatever the code is....   about $150 later in sensors and gaskets, and fixed.

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I had this problem when the engine goes into protect mode you will have to reset with a scanner and reset the fuel air mixture cause it dont reset it self i hate these computer model car

Posted on Oct 27, 2008

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