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Chevrolet Silverado 1500, GMC Sierra 1500, Chevrolet Silverado 2500, GMC Sierra 2500, Chevrolet Silverado 3500, GMC Sierra 3500, Truck
#260 of 403 5.7 L Vortec bogs after warm-up
Nov 21, 2009 (7:47 am)
Hello, first of all I'd like to say that I have scoured these forums for a solution to my problem and haven't found anything that could help. I am a quadriplegic and I don't drive but I am writing this to help my son who has a 1997 GMC Sierra 1500 with a 5.7 L vortec engine with 180,000 miles on it. The truck starts and runs fine until it warms up. After that, you can get the RPM up if you slowly work the accelerator but as soon step on it, the engine just bogs down until you back off the accelerator. It almost seems like it ran out of gas. He has replaced the fuel pump, fuel filter, the ignition module. It's not throwing any codes. Needless to say this is very frustrating and the truck is basically useless under these conditions. He isn't a mechanic and is unemployed at the moment so he just can't start throwing money at it. Any help that I can get here on this forum would be greatly appreciated. Thank you, Paul
#261 of 403 Re: 5.7 L Vortec bogs after warm-up [themajickman]
Nov 24, 2009 (6:35 am)
#262 of 403 Re: 5.7 L Vortec bogs after warm-up [themajickman]
Dec 15, 2009 (9:18 am)
I have a similar problem. My 1999 GMC K1500 5.7L Suburban also bogs down when the accelerated is pressed. It will typically run fine for a while then it starts this. I find that it is easier to drive without the cruise control when this is happening because I can feather the accelerator to speedup slowly whereas the cruise control will try to accelerate more quickly which causes it to start missing/bucking then eventually the cruise will drop out. If I press the accelerator hard, it simply bogs down as 'themajickman' described. I have also found that turning the engine off then back on clears the problem for a few more miles. I have replaced the fuel filter and O2 sensors and I have also put a lot of fuel system cleaner through the system. The problem went away for several months but came back yesterday. I suspected the fuel system but turning it off for a few seconds should not be long enough to let the fuel pressure drop in case it is caused by trash. The engine light has only come on twice even this condition has existed for a long time, and the code did not give a good indication of the problem. The problem is not directly related to speed. One thing that may be unrelated is that if I put it in neutral and shut off the engine while driving (with a straight clear road, of course), it takes the speedometer 5 to 6 seconds to drop to zero. It continues to operate even though the key is off. Could this indicate a buildup of charge somewhere in the electrical system that could be causing the problem. Just a shot in the dark!
#263 of 403 Re: 5.7 L Vortec bogs after warm-up [magiccat75]
Dec 15, 2009 (11:09 am)
Sounds like a bad throttle position sensor
Dec 17, 2009 (5:02 pm)
1999 chevy pickup 5.3 engine gettin codes of po171 and po 174 wonderin what they stand for
#265 of 403 Re: codes answers needed [chuckieboy20]
Dec 17, 2009 (10:37 pm)
P0171 System too lean (Bank 1) O2 sensor detected a lean condition on bank 1 which is the same side as cylinder 1
P0174 System too lean (Bank 2) lean condition on side opposite bank 1
#266 of 403 Follow-up to #262
Dec 30, 2009 (8:16 am)
I replaced the throttle position sensor and at first it seemed like it might be better but on the road, the problem returned. Light came on so read the code again and it said the same thing as before, i.e. the O2 sensors, which I had already replaced. I then cleaned the mass air flow sensor with no improvement. I then replaced the MAF sensor and again, it seemed to run better at first but then the problem returned. To recoup the problem, it gets to where it will only accelerate very slowly. It won't even accelerate as much as the cruise wants to in order to maintain highway speeds on a slight hill. it stutters badly but when the accelerator is pressed hard, it does not stutter, but it also does not accelerate.
I ran another test. On the road, without being able to accelerate beyond just feathering the accelerator to accelerate very slowly, I floored it and the engine speed did not change significantly, didn't go up or down. Thought that maybe it didn't go down because of the transmission still being in gear so I shifted to neutral. The engine still held at the same RPM, even though it was in neutral (no load) and the accelerator was floored.
Here's what has been replaced.
- O2 (all four)
- Air filter
#267 of 403 Re: 5.7 L Vortec bogs after warm-up [magiccat75]
Dec 30, 2009 (8:27 am)
We have 1994 chev 1500 truck was doing the same type of thing - would start to cough and sputter and seem as though it was going to quit running but never actually did. We would have to slow down considerably and found that if we shut it off and let sit for 5 or 10 minutes it would be fine for a while and then it would start again. We went through all sorts of things like map sensor, o2 sensor etc - someone suggested that the distributor is a problem on these vehicles, had it changed and the problem is solved at last.
#268 of 403 2008 Silverado Problem
Dec 31, 2009 (9:06 pm)
We were driving and all of a sudden we heard thisloud bang and all the alert lights went on. We pulled over & turned the engine off, but it would not restart and all of the gages went dead. We towed it home & it did not have any power and the window, which is electric, would no longer go up or down. What would have snapped to cause so many issues to occur at once?
Jan 06, 2010 (1:51 am)
Hi I have a 99 GMC Sierra 1500 Z71 4x4 new body with a 5.3.I was told that 99 only will fit my truck,dose any one know if any other gmc year will fit?or chevy.
I really need the help,the dealer's here in Vermont are no help.