Yay CEL PO174 Again

[Richard Toms]

Hello all again. Have had this code pop up several times for the past month.



2004 ST

178,000 Miles

cleaned air filter

cleaned maf

replaced pcv valve

replaced common elbow

replaced intake gasket



What could possibly be left? Have had a shop play with it. I don't want the stealership to have it next.

 

[scott degroot]

I know it's a long drive for you but I guarantee that I will fix it or I'll pay for the trip...just saying.



Did the shop diagnose it for you or did you just have them replace the intake gasket?



Do you have access to anything that can see live data in the pcm?

 

[Dean Hedin]

Isn't this the code that shows up when there is a manifold vacuum leak? Like when the little rubber elbow going into the manifold on the passenger side front of the engine has a hole in it?



Start the engine and spray some starter fluid around suspect areas where the vacuum leak could be. If you spray an area and the idle smooths out then that is where the leak is.

 

[swshawaii]

Dean- The PCV elbow almost always throws a combination of p0171/p0174 codes. (Lean banks 1 & 2)



OP also said he replaced the "common elbow" and intake gasket. Upper or lower?

 

[Dean Hedin]

Got it, but I still stand by my starter fluid suggestion. Found many a vacuum leaks by this method.

 

[Richard Toms]

The shop said they tested and found the intake gasket was leaking. I don't know if the SCT X3 can show live data or not. It is the only scanner I have for codes. I don't know which intake gasket they changed.



I am just going to call the shop on Monday and say the light is back on. And let them just do what they do. I am just dumbfonded that I keep throwing new parts and it doesn't seem to fix it. LMAO.



Have wondered how long of a list is there a places to check for the PO174. LOL I've done 5, can't be much more.



I don't have the time to be a mechanic. Have to have someone else do it.

 

[scott degroot]

I could rattle off proabally 50 possibilities for lean codes to set. What disappoints me as a mechanic is that the shop who told you the intake manifold gasket was leaking vacuum and did the repair didn't bother to take 5 minutes after the repair to verify that they actually fixed the prolem. Let us know what they tell you next

 

[Richard Toms]

So I had the chance to run by the shop today. I mentioned to them since the light came back on, now I seem to have a rough idle speed, up and down for the first couple minutes after sitting over night. So they did a scanner on it and wrote some stuff down. I don't have copies of what he wrote down. I told them that just yesterday before I filled up my tank of fuel, I put some STP fuel injector cleaner in. They suggested that I run that full tank of fuel and then come back to them when the light pops again and I am low on fuel and allow it to sit over night, so when they come in the morning, they can hear the rough idle. This idle didn't come about until after the new intake gaskets were installed. So whatever that means... I asked about, what intake gaskets did they replace, upper or lower. Mechanic told me this one, this is only the one where the intake attaches to the block basically. So I was like OK. I suggested maybe the PCV valve is clogged up again. So after a short conversation I was about to go about my way and the mechanic noticed the CEL had reappeared. So he then cleared it again.



So here I am again. LOL. I can think of numerous items it could be. But replacing all of that, might as well just replace the truck then. But I don't want to do that.