Winter blues?

[Little Red]

My CEL comes on as soon as the weather cools off in the fall and then I read the codes and I get 171 and 174(o2 sensors,lean). It don't happen in warmer weather. On a warm day like 70 ish the cel don't come on with the same gas in the tank. As soon as it gets below 50 or so, the stupid thing pops up and I get the same codes. I clear the codes and a day later pop goes the cel! Same codes. WTF! I'm tired of this. I'm ready to take out the CEL bulb but I know what a PIA it is. I tried octo booster, higher grades of gas, different brands of gas, no luck! Same stuff. Cool or colder weather CEL comes on. I have no exhaust leaks. The truck is all stock! '97 4.0 What do you think?

 

[Sasquatch_Ryda]

Vacuum leak. Usually intake gaskets on the 4.0L. Spray around the intake with some brake cleaner/ carb cleaner. If you hear the rpm's pick up when you spray a certain spot, there is your leak.

 

[Little Red]

Yeah, I tried that. No luck. It idles at 19-20" of vacuum BTW.New wires and plugs too just because the wires had 240k on them and the plugs had 60 k. Why only in the winter? Engine warmed up and running normal.I looked up the codes on this site and the codes I got with my code reader are different from the ones on this site.Maybe I have a bad o2 sensor from the list on this site.BTW, I did change an o2 sensor on the left bank#2 it was. What a pain! The connector was up by the top of the trans. I had to cut my carpet and take off an access panel to get to it then my fingers and arm was too fat to get in there! I had to change it because the cel would come on as soon as I started the truck after clearing the code. With this problem the cel will come on only when it's cold out and after several starts.I hate to buy parts and hope. I don't believe in that. A mechanic nails it,a parts changer is just that,a parts changer!

 

[97RangerXLT]

I see that you have a 97. there is a TSB for the lean codes you are receiving. you need to replace the fuel rail gasket. (the one between the fuel rail and lower intake. this TSB is for the 97 Rangers, explorers and Aerostars only. basically the gasket fails between the ports causing an internal vacuum leak and thus the lean conditions.

Not too bad of a job to do, you have to remove the upper intake to get at the fuel rail. lots of vacuum lines. replace any that seem loose or worn while you are in there.

AJ

 

[Little Red]

Thanks, Sounds logical but why only when in the fall and winter,late winter and spring? It never comes on in the summer. SW Pa. weather. The cel comes on usually after several starts,sometimes sooner it seems on short trips . I read that a code of that type will come on after 4 starts. I can get more starts than that sometimes especially if a warm front comes through. As soon as the outside temp gets above 55 or so the light stays off.I really think it's the winter blend of gas. And yes,there are winter and summer blends of gas. Thank GOD that I don't have to pay someone to read my codes and get the same ones time after time. And have them change part after part at MY expense! The drivability has not changed ,I just don't like that light on and having to clear the codes 3+ times a week. I'm ready to get and old carburatered truck and blow the exhaust up the EPA's Giggy! Stupid pollution controls! But that's another story.

 

[feellnfroggy]

Differnet metals and other materials have differnet shrink/swell rates in different temps. When your hitting those lower temps your seeing severe effects of this. Most likely in the metal from the fuel rail or maybe the gasket itself.

 

[Little Red]

Thanks but I don't agree. The engine goes from ambient temp to 180 deg. and back thousands of times in it's life. What is the difference between 60 deg. and 45 deg. going to do to the manifold? Can anybody measure that? I doubt it. Bearing clearances are not affected between freezing and 90 deg. that can be measured by normal methods so I don't think manifolds will move much. I had the cel on this evening left over from yesterday and cleared the codes with a cold engine. I drove 3 miles to a Pharmacy and left the pharmacy and within a block the CEL came on(same codes). I drove 10 more miles and stopped and cleared the codes again and proceeded 30 more miles and had 2 more shut offs and starts and the light stayed off. The stops were at the most 45 min. so the engine never cooled off real good. It was 50 ish out.I guarantee you that tomorrow morning the cel will come on after a good cool down tonight. It's supposed to get in the low 30's. I really think I got a bad heating element in an o2 sensor ,I got 4 of the little darlings. I'm going to ohm them out(the heating elements) and see what's up. Then I'll know.

 

[Sasquatch_Ryda]

You would have codes for that is it was HEGO problem....

 

[shane96ranger]

My buddies 98 Explorer had the same symptoms, but IIRC correctly his codes said lean left and right bank. We looked all over the place for a vacuum leak in the intake and everything checked out fine. Then we discovered one of the vacuum lines on the DPFE/EGR Pressure switch was collapsing. When we took the lines off they were so brittle that one of them fell apart. We replaced those hoses (only one was worse than the other because it gets a lot hotter apparently) and it hasn't come back on since.

Might not be it, but worth looking at.

 

[Little Red]

Thanks, I check that out again. The codes 0171 and 0174 came back this morning. I caught them before the cel came on. According to the codes on this site they point to one in the right side rear. I'm gonna crawl under there tomorrow. I can't get over the fact it only doesn't do it in the summer.I lived with it last winter,I want to fix it this time.

 

[97RangerXLT]

one reason you might be getting the codes in cold weather is you have a small vacuum leak, and cold air is denser than warm air, so the vacuum leak is pulling in more air volume when it is cold than when it is warm out.

I would still look at all of your vacuum hose connections, check the ones to the egr and dpfe (I think that is what is is called) sensor real close.

but being it is a 97, I would put money on the lower fuel rail. when I did the valve cover gaskets on my Ranger, I decided to look at the fuel rail gaskets and saw that mine was just starting to pull out of place between the back two intake ports. maybe that is what yours is doing...

AJ

 

[Little Red]

Thanks but...small vacuum leak? Come on. How much does it take to lean out a mixture 20 minutes after you start the truck? I think it would be sucking air enough to suck a golf ball through a garden hose! I disconnected vacuum hoses on purpose and the CEL never came on.Well today it was 50 ish out and I drove 30 miles with clear codes and when I parked the truck I checked again and there were NO DTC'S. The truck ran smooth as silk too like when after you change the oil or wash it LOL! I'm tellin ya it's temp related! Whisky Tango Foxtrot! There seems to be nothing electrically,vacuum,mechanically wrong with the thing if it runs with no issues in 50 deg temps or more! Maybe it's the stinking winter gas that's oxygenated and blended with moonshine! I think my truck wants to go down South which ain't a bad idea for bofe of us! I'm outa here. Thanks for all your replys friends seems we can't come up with a difinitive answer.

 

[97RangerXLT]

seems like another member here has the exact same issues you do, only his show up below freezing...Check out Eagle Scouts thread. if you find the vacuum leak or another solution, let us and EagleScout know.

here is his thread:
http://www.therangerstation.com/forums/showthread.php?t=96471

AJ

 

[feellnfroggy]

Thanks but...small vacuum leak? Come on. How much does it take to lean out a mixture 20 minutes after you start the truck? I think it would be sucking air enough to suck a golf ball through a garden hose! I disconnected vacuum hoses on purpose and the CEL never came on.Well today it was 50 ish out and I drove 30 miles with clear codes and when I parked the truck I checked again and there were NO DTC'S. The truck ran smooth as silk too like when after you change the oil or wash it LOL! I'm tellin ya it's temp related! Whisky Tango Foxtrot! There seems to be nothing electrically,vacuum,mechanically wrong with the thing if it runs with no issues in 50 deg temps or more! Maybe it's the stinking winter gas that's oxygenated and blended with moonshine! I think my truck wants to go down South which ain't a bad idea for bofe of us! I'm outa here. Thanks for all your replys friends seems we can't come up with a difinitive answer.

Seems like you have figured out everything except what your problem is. And considering that you dont know what you problem is instead of spitting out what you think isnt working, why not test one of these theories. You MIGHT be surprised, maybe not, but just maybe.

 

[trader007]

mass airflow sensor dirty? dust on the sensor can cause the trucks ecm to think its much warmer outside, which will lean out the mixture. because its actually cold air coming in though, the mixture is too lean and the o2 sensors pick that up. so you get o2 trouble codes but really its caused by the maf sensor.