My CEL is on....again. Late last winter it came on for the first time. Codes read lean on both sides, P0171, P0174. Thought it might be the fuel filter since Missouri had just started putting ethanol in all gas. Worked for a couple of weeks but came back on. Tried the same thing again only the weather warmed up and it didn't come back on during the summer. Then last month it came back on. Seems that if temps are in the 30's and once the truck warms up the light comes on. I tried cleaning the MAF and the Idle Control Valve. Cleared the light but it's back on again after a couple of weeks. I did notice that it made the loud whining sound last summer that others have talked about when the Idle valve is not working properly. The truck runs fine, but the light keeps coming back. '98 Ranger with 4.0 V6, 145,000 miles. Thanks.

 

http://www.explorerforum.com/forums/...d.php?t=171819

 

Thanks for the link. I was hoping it would be somthing less involved than the gaskets. I am curious as to why the problem only occurs in cold weather. I thought that a vacuum leak would not have an outside air temp issue to it especially when the light comes on only after the engine is good and warm. Its seems like more of a fuel/air mix regualtor thing. Like when the choke got stuck on a carb, back in the day. Never had the problem in warm summertime weather. Any thoughts on that?

 

I've personally had a piece of lint on one of the MAF wires cause this code. (on a F-150) Truck ran fine but would throw a code after a couple hundred miles. I took the MAF aparts and sure enough.. there was a little piece of lint. I spray cleaned it with the special cleaner and that's all it took.

The intake gasket problem is a common thing from what I hear.

Rich

 

I cleaned the MAF with the eletronic component cleaner. The one that doesn't leave a residue. I only disconnected the large air hose that the MAF is connected into and sprayed the housing out. Are you supposed to do any disassembly to the actual MAF to clean it? I don't remember seeing the wire(s) you mentioned.

 

On my ranger there is a rectanglular metal box thats removed with two screws. Look into it and you'll see the wires.

On older / other models of fords there is often a similar plug in (with 2 or 3 screws) type of MAF. But its plastic and has a *tube* or passage that the air flows through. The wires are inside there and being careful you can remove the actuall wire/module from that sub-assembly. If not just spray in the tube/passage.

Just spraying into the large round MAF housing won't usually clean it good enough. It's just a housing.. the real "cleaning" needs to be done on the wires.

Rich

 

Thanks for the help. I'll give it another try. I also think the Idle Control Valve will need to be replaced. It was making the howling noise that others have referred to. That seemed to be more the case in hot weather and especially when I was driving in stop and go traffic. Hopefully one of the two cure the problem.