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PO171 and 174
by flynlow22 on Jun 28 2017, 2:04 PMI'm having some problems with this one. This is my personal truck, it is a 2004 GMC Sierra 1500, 5.3, VIN T. This issue only happens in 100 + degree weather when pulling a hill. The water temperature is normal and all other parameters are normal then all of a sudden the long term fuel trim starts climbing to 20% plus, the truck looses power, then ultimately stops running. The codes that are present when this occurs are PO171, PO174, and PO300. If I open the hood and let things cool for 15 - 20 minutes, the truck will normally start and run fine. This problem has been going on for two summers. Over that period of time I have replaced the fuel pump, mass airflow sensor, intake manifold gaskets, map sensor and throttle body. I have thoroughly checked for vacuum leaks, checked the air intake after the MAF, and disconnected the power brake booster, all with no change whatsoever, in fact, the problem is getting worse. Any input would be greatly appreciated.
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my first post in these forums, so bear with me please.
you're getting the lean codes first. these are happening due to the ecm pulling fuel, or a restricted fuel supply. this is in turn causing the random misfire code. it looks like you've covered most of the more common poss. causes already, but i found a tsb for an updated fuel pump for high elevation/high temps(above 80F) check tsb #05-06-04-046A. is that the one you installed?
hope this helps!
my first post in these forums, so bear with me please.
you're getting the lean codes first. these are happening due to the ecm pulling fuel, or a restricted fuel supply. this is in turn causing the random misfire code. it looks like you've covered most of the more common poss. causes already, but i found a tsb for an updated fuel pump for high elevation/high temps(above 80F) check tsb #05-06-04-046A. is that the one you installed?
hope this helps!