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P0171 and P0174 Codes

irishincali

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I have a 2001 Mounty 5.0 with AWD. Has been hard to start and now all of a sudden check engine light has come on and got codes P0171 and P0174. I checked for vacuum leaks both visual and using the ole starter fliud trick. Anybody have any other ideas? MAF or IAC gone possibly gone bad?
 


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2000StreetRod

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Not the IAC valve

The IAC valve will affect your idle speed but should not result in lean codes for both banks. I'd start with cleaning the MAF sensor with MAF sensor cleaner since you've already checked for vacuum leaks. Then I would replace the fuel filter if its due and follow that with a bottle of injector cleaner in the fuel tank.
 




irishincali

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ok, I have just recently changed the fuel filter and ran some injector cleaner through the system so I can check those two items off the list. I will clean the MAF tomorrow. Is there any chance it can go bad and need to be replaced? Thanks
 




BobWiersema

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jremington59

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If the above suggestions don't fix the problem, which they should, then you would want to have your fuel pressure checked.
 




2000StreetRod

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MAF sensor reliability

MAF sensors are quite reliable but they do go bad. Most of the time they're just dirty. A lot of the high flow cone air filters contain excessive oil. I always remove the packaging from a new cone air filter and let it air out for several weeks before installation. I make a point to clean my MAF sensor 30 days after installing a new air filter.

The PCM relies on the MAF sensor to determine the load on the engine. The PCM checks the MAF sensor voltage output to make sure it is within the normal range. The PCM also compares the MAF sensor output with the TPS output and engine speed for reasonableness. It is very difficult for the PCM to identify a bad MAF and set the corresponding DTC.

I agree with jremington59 that if you still have problems after cleaning the MAF sensor then you should test your fuel pressure. You could have a bad fuel pressure regulator.
 




jocasio

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Hello all:

Sorry to piggy back off of this thread. I, too am experiencing the same problems. I have seen several posts (on this and various other sites) on what items to check. Unfortunately, I have not come across any sites that show how to do the checks.

Would anyone out there have a step by step on how to perform these various tests? For example, I'm not entirely sure how to check for a vacuum leak (although I know you have to spray something and see if it gets sucked in - I don't know where).

Many thanks for any asssitance you guys can further give!

jocasio
 




irishincali

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Where is the PCV located on this bad boy?
 




jremington59

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The first thing you want to do is check and clean the map and maf sensors. That's most likely your problem.

Can you hear a noticable "hiss" anywhere under the hood? Follow all vacuum lines and make sure they aren't rotted and havent gotten pulled off the connectors. After that you can spray wd 40 around the intakes and lines and see if your engine rpm's increase.
 




BobWiersema

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Where is the PCV located on this bad boy?

This should help.

http://www.explorerforum.com/forums/showthread.php?t=157568

Look at post #7. by 410Fortune
This is the picture from post 7.

pcv.jpg

That picture is of the rear of the engine.
 




irishincali

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WOW!!!!!!! of course it couldn't be easy to get to, lol. Any ideas or tricks for gettin it out of there? Do I need to pull the top end?
 




irishincali

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I found and cleaned the MAF but what is the MAP sensor?
 




BobWiersema

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I found and cleaned the MAF but what is the MAP sensor?

Manifold Absolute Pressure , I don't think you have one. Ford uses DPFE (Differential pressure feedback). If that's not working correctly you will get an error related to the EGR system.


Did you get at that PCV yet? I have read about problems with the rubber grommet that it goes into.
 




irishincali

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Yea, got the PCV but can't get my hand back behind there enough to replace it so I think I'm gonna take it to the shop and let them mess with it. Didn't really want to spend the cash, but gotta get it fixed. Any idea how to check the fuel pressure?
 




irishincali

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Got it fixed!!!!!! Was the fuel pump. Thanks for all the input and help. Love this site!!!!!
 




Dirt n Oil

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I have the same codes. Did you replace the fuel pump, and has that worked out long term? Did your mounty take 2 or three start attempts for a while leading up to it throwing codes?
 




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