Code P0171 and P0174 during very cold weather only

[Eagle_Scout2002]

I have done a bit of searching and found a number of things for these codes. My only problem, is that these codes only come on during below zero temperatures. No idle issues, running issues, etc. Had this code once last winter as well during a really cold spell. Temperature last night was about 1 below. Tonight it is supposed to be 20 below BRRRRR. Any thoughts anyone on this issue. I plan to check for vacuum leaks, check fuel pressure, and clean the MAF. I was just wondering if anyone else has seen this issue during really cold weather. Oh, this is on a 1999 Ford Ranger 4.0L. Thanks everyone.

Ray

 

[envious8420]

what elevation are you at?

 

[atvkid4eva]

you have a vacuum leak. my 97'ranger threw those exact codes about a month ago and it turned out to be the fuel rail gasket to the intake manifold.it will eventually start running bad and have an irratic idle. a vacuum leak causes the engine to run lean which isnt healthy for a long period of time. im almost 100% sure you have the same gasket leak i did. once i replaced the gasket the lights went away and the truck runs perfect. hope this helps.

 

[97RangerXLT]

I second the vacuum leak theory.

Check all of your vacuum lines around the upper intake, be sure to look at the pcv valve hose. if it fits loosely, that might be just enough leak to give you your codes. make sure all the fittings are tight. also check the hoses to the egr valve.

take some carburetor cleaner and spray it in different areas around the intake and various vacuum hoses. if you get a sudden engine rev, that is where your leak is.

spray some carb cleaner along the base of the upper intake. if it revs there, your upper intake could be loose or warped.

The fuel rail to lower intake that atvkid is talking about is a common issue on the 97 model year, and there is a TSB on it. probably not your issue as you have a 99, but if all of the other things check out, that is something to look at. it will involve removing the upper intake and the fuel rail. Not a hard job, but it can be aggravating to get the upper intake separated from the egr tube.

remember, check the easy and cheap stuff first!

AJ

 

[97RangerXLT]

oh, Little Red has the exact same issue/ symptoms you do... if you do find where vacuum leak is or anything else that is causing the problem, post it up for him.

http://www.therangerstation.com/forums/showthread.php?t=96004

AJ

 

[Eagle_Scout2002]

what elevation are you at?

The elevation here is about 2600 feet above sea level.

Ray

 

[Eagle_Scout2002]

This weekend I will check for vacuum leaks and clean the MAF. Dont have time till Friday. Worked 10 hours today (not including the 2+ hours of drive time). Will probably work the same or more tomorrow. The nice thing is that I then get 4 days off. Gonna be a busy weekend. Once I find the problem, I will deffenentally post it here as well as for Little Red.

Ray

 

[Eagle_Scout2002]

On a side note, I LOVE how my Ranger handles in the snow. The good snow tires probably help a lot, but it handles great. It is kinda a cold blooded thing though and sure doesnt like this -18 degree weather. Takes a while to get warm in the cab. But it handles great in the snow. Just had to share.

Ray

 

[Eagle_Scout2002]

Well checked for vacuum leaks and none found. Checked MAF and it is clean. Everything is checking out good. Hooked up a scan tool and checked the engine data information and everything is within specifications. Drove it after clearing the codes and no codes came back. Temperature warmed up to about 20 degrees. I am kinda at a loss at this point. Will have to see if the codes come back while driving it next week.

Ray

 

[Eagle_Scout2002]

Ok, so the temperature warmed back up to above 20 degrees all week. Drove my Ranger all week and no codes came back. This phantom issue is annoying. Could there be an issue with my IAT sensor when the temperature gets so cold? Well have a good night everyone.

Ray

 

[Bruce]

I've got the same thing going on on my 2002 ranger and i have sprayed carb cleaner all over the place. It dont matter what temp is outside and it may set the 3 times a day then it might not set a code for 2 days..i replaced my MAF just to see if that was it so we will see.

 

[Anger]

I just threw these codes on my 2000 4.0.

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[pcollins]

i just got these codes too my game plan for tomorrow is to clean the MAF sensor, which i've had no luck finding. slap me silly but where is it? Then i'm going to get out my trusty carb cleaner and see if i cant make the engine rev up a little. Anyone got any other advice?

 

[sholzy]

i just got these codes too my game plan for tomorrow is to clean the MAF sensor, which i've had no luck finding. slap me silly but where is it? Then i'm going to get out my trusty carb cleaner and see if i cant make the engine rev up a little. Anyone got any other advice?

First sensor in the intake tube coming out of the airbox.

 

[pcollins]

Thanks! hopefully this is something simple. I have reciepts from previous owners in my truck stating that the fuel rail to intake gasket was replaced already at around 50k miles. 150k on it now. I really don't want to have to tear off the intake manifold and injectors just to fix this....