Check Engine light (Lean Code)
 

Hi Guys,

I keep getting P171 & 174 lean codes. I have 2001 sport trac 4.0 SOHC engine. I replaced the MAF sensor and codes keep comming back. I was toldI need to change the lower intake manifold gasket.

Is this a big job, can I do it in my garage. I am pretty handy, I havechanged regular intake manifold gaskets but this lower thing is new to me.

Thanks for any help

RE: Check Engine light (Lean Code)
 

how sure are you that it's you intake gasket , the manifold could be cracked , or it could be just a vacuum leak you need to do a good visual inspection . i can tell you how to take the mainfold off but you should make sure thats the problem first (can you hear or feel any air leak) if you want to mickey mouse it,if you smoke or have a friend that does blow it at the mainfold , using a flashlight look and see where the smoke is getting sucked in to. you can easily remove the manifold at home with simple tools .

RE: Check Engine light (Lean Code)
 

Not sure why you replaced the MAF sensor, lean codes can be many things. The SOHC is notorious for intake leaks. My favorite methodfor checking isto poor water over the top of the intake with the engine idling. I have had some stall because the leak was so bad. Not a bad job to do, no coolant to spill like the older engines.

RE: Check Engine light (Lean Code)
 

I have the same problems with my 1998 v6 explorer sport.. Ford replaced the fuel filter, IAC valve and did a complete tune up. I bought a spray and cleaned the MAF valve, it is spotless. On cold start the engine will not idle unless I keep it at around 1500 rpm. Check engine light is on. This only happens in cold weather. When the weather is warm. I remove the positive battery post, reset the computer, no check engine and all is fine until cold weather. Then same thing all over again

RE: Check Engine light (Lean Code)
 

grefra,

I'm not sure if you've solved your problem but I'm willing to bet you that the rubber elbow attached to the PCV valve has deteriorated so much as to cause a leak. Unfortunately you will probably only find the tube assy at the Ford dealer. Fortunately, they'll only charge about $20 for it.

Let me know if this helps.D
Darrell Chapman

RE: Check Engine light (Lean Code)
 

I agree with Darrell, had the same problem on the wifes explorer.