Contour Enthusiasts Group Archives Forums General Troubleshooting P0171, P0174

My problem started when I changed the air filter and cleaned the MAF and TB. I inadvertently left the small hose off the rear of the intake (it goes down behind the engine) for about a mile. Car ran bad, threw mucho codes later. After re-connecting the hose and clearing the codes, CEL came back with P0171 and P0174. I've researched here, checked for intake and vacumn leaks over and over, replaced PCV valve and fuel filter (it was time) to no avail. Before I start replacing other stuff, does anyone have any ideas of where to look for the problem. I also recently replaced the plugs with Bosch +4. The car runs great, idles fine. Throttle hang may be a tad worse but not bad. Got to clear those codes so I can get the damn thing smogged for DMV. It must be something I did when I took the intake apart.
Thanks. This is a great site.

Check the accordian air tube to see if there are any cracks or splits.

Did you use a new TB gasket or reuse the old one? Did you install the gasket upside down?

Did you use a Motorcraft PCV valve or some other brand?

I'm certain someone else will step in and flame you for using thos +4s.

Steve

Thanks, Steve.
The acccordian air tube is in great shape.
I did not remof=ve the TB - just cleaned inside it with TB cleaner.
Replaced the PCV valve with an aftermarket unit but I'm sure the original one was OK.
Sorry about the +4s - replaced them before I read that maintenance thread. They seem to work fine but not better than OEM as advertised.

Anybody else have any suggestions?
Another new symptom is engine pinging under full throttle, low rpm.
I cleaned the TB with a rag, going as far in as I could and cleaning both sides of the butterfly. Could I have damaged the TB in some way?
This is driving me nuts.
Should I remove the EGR valve and clean it? Or what?

pinging on acceleration is because of a way to lean of mixture, it is also harmful for the engine to be so lean.

Intake manifold gaskets/vacuum leaks are the most common reason for PO171/PO174 at the same time

If you have done all you think you could bring it to a shop then.

Thanks, Hitman.
Just spent another half-hour troubleshooting to no avail.
I guess the dealership is most qualified to hunt this down. My local mechanic would spend hours and hours, I just know it.
The ping is not very severe and seems to go away with increase in rpm.
LLL

Hearing the words dealership and qualified used together makes me . Unmetered air can only come from a couple of places. Seeing as how both banks are running lean I would suspect either a gasket leak UIM/LIM, TB or a leak between the MAF and TB.

Really man for what the dealer will charge you for a diagnostic fee you could have brought the UIM/LIM gaskets. Might as well replace them first.

this is a previous poste I posted about a year ago. I am in Ontario Canada So the weather is a bit different ha! ha! but check it out any way. codes never came back. I had the same intermittent vaccuum leak which acted up every time the weather got cold. Codes were p0171 & p0174.
I finally found it by spraying throttle body cleaner around the intake plenum where it bolts to the top of the intake stack. It disappeared shortly after detecting it.
I replaced the upper intake gaskets & have had no more codes for two weeks now. Codes would re-occur about once a week before fixing.

Hope this helps.
My car is a 96 mystique 2.5 24 valve

I have sprayed the better part of a can of TB cleaner all over the intake, vacumn lines and manifold area trying to find this leak. Logic would seem to indicate that the problem is related to something that happened when I removed the intake to clean the MAF sensor and TB. It would be unusual, I think, for an engine with less than 75K miles on it in Socal to develop a manifold gasket leak.
I will keep looking.
Thanks for all your suggestions.
LLL