P0174 code - safe to go on road trip?

[expredator]

I have a 2013 Tahoe LTZ with 80k miles. The engine light came on today and I pulled a P0174 code. It seems like the issue could be minor but also a serious problem. I am going on a 4h road trip in a couple days and was wondering what I can do in the meantime to diagnose or fix the problem, and if it is safe to drive? Don't want the car to break down in the middle of nowhere....

Edit: For what it's worth, I was accelerating somewhat hard when the light came on. Not sure if it means anything

Edit2: I also started to notice a whistling sound when driving slow. I read that a clogged fuel injector could underlie this and the P0174 code. Does that make sense? How I go about unclogging the fuel injector?

 

[OR VietVet]

P0174 Causes​

• Dirty or faulty mass airflow sensor
• Vacuum leaks – PCV hoses, vacuum hoses, intake manifold gasket.
• Weak fuel pump
• Clogged or dirty fuel injectors
• Clogged fuel filter
• Exhaust leak
• Faulty oxygen sensor
• Faulty air-fuel ratio sensor

It states "Vacuum Leak(s). That could be the whistle sound and the source of the problem....Or Not

 

[Foggy]

Sounds like a minor vacuum leak to me from info...
IF it's an injector issue, you could run 2 bottle of techron concentrate in your
fuel and see if that helps... I use techron in all my (and custs) fuels at every oil change
to prevent issues. It also keeps the fuel sending units from sticking

 

[OR VietVet]

Sounds like a minor vacuum leak to me from info...
IF it's an injector issue, you could run 2 bottle of techron concentrate in your
fuel and see if that helps... I use techron in all my (and custs) fuels at every oil change
to prevent issues. It also keeps the fuel sending units from sticking

Exactly why I run Chevron fuel. The Plus/Mid grade is supposed to have Techron in it.

 

[expredator]

P0174 Causes​

• Dirty or faulty mass airflow sensor
• Vacuum leaks – PCV hoses, vacuum hoses, intake manifold gasket.
• Weak fuel pump
• Clogged or dirty fuel injectors
• Clogged fuel filter
• Exhaust leak
• Faulty oxygen sensor
• Faulty air-fuel ratio sensor

It states "Vacuum Leak(s). That could be the whistle sound and the source of the problem....Or Not

Thank you for the list! So, interestingly the engine light turned off by itself today, but then I was on the highway and it turned on again. Not sure if it's the same code but I would guess so. It seems that the engine light turns on when I accelerate hard (like on the highway when I'm on an incline).

From the list you provided, can we narrow it down based on what I am observing?

 

[OR VietVet]

I already narrowed down because of whistling sound when driving slow, like maintaining same speed instead of accel hard. Vacuum is highest at idle or maintaining a steady speed and if vacuum leak is bad enough you can hear it BUT you should also have at least a rough idle and likely a dead cylinder if leak is that bad. The list I supplied should be inspected. Just cleaning MAF may fix.

 

[OR VietVet]

What does the air filter look like? How filthy is it? Need to get a fuel pressure test and hook up a Tech II and check it under hard accel. While you have the Tech II hooked up, check the oxygen sensor operation.

 

[expredator]

Ok so a couple of updates:

- The check engine light has continued to come on and off over the past week, especially when I accelerated ******* the highway and bringing the RPM to over 2.5K

- Yesterday, my AC stopped cooling. Interestingly, I had an AC job, including recharging, adding a dye etc done about 1.5 weeks ago. The reason for that was that I thought my AC was not getting cool enough and that the passenger side was not blowing air as strong as the driver side. The mechanic did not find any issues, including any leakage. He asked me to come back later this week to check is there is a leakage occurring only after driving the car a little.

- Anyway, I changed the air filter (looked dusty and old, but no major dirt) and sprayed the MAF while I was at it. The AC now cools again and the check engine light is still on. I ordered an OB2 reader to erase it.

- I went to Autozone yesterday after doing the work described above to see if there are new codes. Their reader read again P0174, but also P0171 and P0101 as secondary DTCs. I am wondering if once the check engine light is off it'll stay off now that I cleaned the MAF. Otherwise, would I have to replace the MAF in the next step?

- About the whistling noise: I have only looked for obvious cracks in the big hose where the MAF is located and didn't find any crack. Again, when I am slowly accelerating, or am in P or N and accelerate, I can hear a not so loud sound like someone left the window open and it's windy outside. Is that "normal" or does that definitely say that I have a vacuum leak somewhere?

- I should mention that my idle is rather smooth. I also filled up at Chevron and Texaco, respectively, once each with no effect on the check engine light.

 

[B-train]

Look under top engine cover. Your vacuum line for the booster mounts to the rear of the intake plenum. You could pull it off the booster as it's running and see if anything changes. Also, put your finger over the end of the hose - suction should be like trying to drink a McDonald's shake when they serve it to you - picture your cheeks pulled in and not much moving up the straw. LOL

Also, on the passenger side of the motor is your PCV valve circuit and there is a hard plastic hose that runs from the intake pipe to the passenger side valve cover area.
Check for cracks or disconnection.

 

[B-train]

Then other possibility of a vacuum leak is the intake gaskets. When you have the top cover off, you could run a hose along both sides below the valve covers. Just a steady, slow stream. If there's a leak, the engine might stumble a bit and you'd see white coming from exhaust from steam generated by water consumed. Don't douche the motor, just give it something to suck in if there's a leak