P0174 code - safe to go on road trip?

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tungsten

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I have the same whistle when cold,havent looked yet but Im assuming its the air filter box at one of the clamps?
 
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expredator

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Thanks B-train for your thoughts. So, my check engine light turned off by itself today and even though I accelerated quick and hard multiple times since then, it has not come on again yet. I am hopeful that cleaning the MAF solved the issue.

As to the whistling noise, no clue if it's even a real issue or if I am just being paranoid. I think at this point since there is no engine light on I will just see how it goes before I dig deeper. Thanks y'all for all your help!
 

InterceptorF

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Do a fuel pressure test if you can. A little story... I have a 2004 Tahoe LS. I use it for long trips. My wife took it from Colorado Springs CO to Tucson AZ. At Truth or Consequences NM the Tahoe started bogging down and barely had any power it was at a half tank. The check engine light was on p0174. The mechanic decided it was a plugged catalytic converter (253K miles, so fine repla$e it). After removing the Y pipe (realize the Tahoe cooled down while he removed the Y pipe and they filled the tank before going to the shop), it ran fine so he ordered/replaced the y pipe/catalytic converters and sent my wife on her way. When the Tahoe got to a half tank it started doing it again so it was NOT the catalytic converters. She filled the Tahoe and let it cool down. It ran fine until it again got to a half tank and it started bogging again. She filled up and kept it above a half tank and made it to Tucson. I had to fly into Tucson and replace the fuel pump/filter -problem solved. I believe that at a half tank the fuel pump was not fully submerged and was getting warm causing the pressure to drop. You may be seeing the start of a weak fuel pump. Hopefully its a vacuum leak; and replacing the intake gaskets is easier than a fuel pump - I'd do the fuel filter/pump and intake gaskets and get rid of all those variables.
 

OR VietVet

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Do a fuel pressure test if you can. A little story... I have a 2004 Tahoe LS. I use it for long trips. My wife took it from Colorado Springs CO to Tucson AZ. At Truth or Consequences NM the Tahoe started bogging down and barely had any power it was at a half tank. The check engine light was on p0174. The mechanic decided it was a plugged catalytic converter (253K miles, so fine repla$e it). After removing the Y pipe (realize the Tahoe cooled down while he removed the Y pipe and they filled the tank before going to the shop), it ran fine so he ordered/replaced the y pipe/catalytic converters and sent my wife on her way. When the Tahoe got to a half tank it started doing it again so it was NOT the catalytic converters. She filled the Tahoe and let it cool down. It ran fine until it again got to a half tank and it started bogging again. She filled up and kept it above a half tank and made it to Tucson. I had to fly into Tucson and replace the fuel pump/filter -problem solved. I believe that at a half tank the fuel pump was not fully submerged and was getting warm causing the pressure to drop. You may be seeing the start of a weak fuel pump. Hopefully its a vacuum leak; and replacing the intake gaskets is easier than a fuel pump - I'd do the fuel filter/pump and intake gaskets and get rid of all those variables.
I have recommended many times here, to think of a 1/4 tank as empty and a 1/2 tank as a 1/4 tank. That fuel in that tank, IMO, cools the fuel pump and therefore the pump does not work as hard to get fuel to the front. I am glad yours is fixed but that had to be one finicky fuel pump in 1/2 a tank. I am assuming there was something wrong with that fuel pump assembly that would have not allowed any pump motor to work properly. My scenario is something that can cause problems over the long haul. At 1/2 tank, there just seems that there was something else besides the motor itself that was causing the problems. I also am assuming that when you were experiencing the problems and you stopped to top off the tank, that you were actually adding 1/2 tank worth of fuel.
 

InterceptorF

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I have recommended many times here, to think of a 1/4 tank as empty and a 1/2 tank as a 1/4 tank. That fuel in that tank, IMO, cools the fuel pump and therefore the pump does not work as hard to get fuel to the front. I am glad yours is fixed but that had to be one finicky fuel pump in 1/2 a tank. I am assuming there was something wrong with that fuel pump assembly that would have not allowed any pump motor to work properly. My scenario is something that can cause problems over the long haul. At 1/2 tank, there just seems that there was something else besides the motor itself that was causing the problems. I also am assuming that when you were experiencing the problems and you stopped to top off the tank, that you were actually adding 1/2 tank worth of fuel.
It was a difficult thing to troubleshoot since a fuel pump 'usually' completely fails.
 

Geotrash

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It was a difficult thing to troubleshoot since a fuel pump 'usually' completely fails.
Not on these. On my 2007 my only symptom was that occasionally the Stabilitrack/TC light would come on with the message in the DIC that it was disabled, followed by a CEL - but only on the highway after several miles. Monitoring the fuel pressure gave me my smoking gun - the pressure regulator in the pump assembly was starting to fail. Had a shop put a new OEM pump in it and haven't had a problem since.

Edit: Thinking about this some more, the Tech2 captured messages from the onboard sensors that there were fuel pressure spikes as well. I don't remember what the code was, but it's what prompted me to start monitoring the pressure.
 
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