CEL codes

[Ft.WorthHoe]

Ok so I have two codes p0171 and p0174. I have changed the fuel pressure regulator, spark plug wires and plugs, all 4 o2 sensors and MAF. This CEL light only seems to come during the colder seasons. Any ideas or things that y'all may have had to change to get rid of this problem? I did the Swiss cheese air box mod and that's when this CEL came back. Could this maybe be the prob.?

 

[JennaBear]

Those are lean codes. What MAF did you change to?

Sounds like a bad vacuum leak or a bad fuel pump.

 

[Ft.WorthHoe]

I bought a MAF from autozone. Do I maybe need a different one?

 

[JennaBear]

Is it OEM?

 

[Ft.WorthHoe]

Also how do I check for vacuum leaks? Or how do I check to see if the fuel pump is going out? I had this same issue last year around this time but during the summer no CEL. Thanks

---------- Post added at 01:15 PM ---------- Previous post was at 01:13 PM ----------

Is it OEM?

It says Delphi on it if that helps. I just went up there and asked for the MAF that I needed and that's what they gave me over the counter.

 

[PlazaEJ]

I think you're just delaying the inevitable.
Probably, Intake manifold gasket leaking.
If the leak is towards the top, you can detect the leak by spraying starting fluid along the gasket mating surface and listen for a change in RPM. If the leak is toward the bottom of the mating surface, it'll be difficult to detect.

BTW, as long as you're removing the intake, you might consider replacing the knock sensors, at the same time. Don't ask how I know.
What year, and engine do you have?

EJ

 

[Ft.WorthHoe]

I have an 04 with the 5.3 liter.

---------- Post added at 12:13 PM ---------- Previous post was at 11:55 AM ----------

I think you're just delaying the inevitable.
Probably, Intake manifold gasket leaking.

EJ

How hard is it to replace this if it is the problem? And also is it kind of pricey? Thanks for the feedback, I really appreciate it.

 

[01Konvict]

sounds like the intake gaskets to me since those codes come from either the MAF failing or vacuum leak or intake and you have done everything except gaskets. I have to do my engine soon cus the symptoms are starting to show in cold weather

 

[delta579]

I agree sounds like a VAC leak. There is a line going into the top, in the middle of the intake manifold. It should have a short piece of flex line connecting it to a hard plastic line. This is the PVC vacuum line. Disconnect the line at the manifold and plug a VAC gauge into it. VAC at idle should be 17-20 lbs., with a steady needle, the higher the better. I think it the intake manifold gaskets also. I used the Felpro gaskets that hang on the head bolts. Not a hard job, 2-3 hours. Replace knock sensors when you do job. Plenty of YouTube vids on how to do the job. I highly recommend that you wash/clean out the intake manifold with mineral spirits when you have it off. They get filthy over time.

 

[Ft.WorthHoe]

Ok so I finally gave in and took the truck to the shop so they could do the smoke test on it. I tried with the carb cleaner and couldn't find anything. So the problem they found was the oil filler neck was cracked on the bottom and the MAF was bad. Thanks everyone for the input, really appreciate it.