I know this is not really the proper board for this but I trust the knowledge of this place more than any other. Vehicle is question is dads 96 Windstar 3.8L with almost 100K miles.
Problem started about two weeks ago with a code P0171 lean condition. Then further developed into a code P0171 and a P0174, both lean conditions of each bank of cylinders. He replaced the front 3 plugs with Motorcrafts but at his age he can't quite reach the back 3, I plan to try them on Friday. He's also tried the big bottle of Chevron FS Cleaner in the tank. All to no avail, where should I start?
I was thinking go ahead and change the back 3, try to change fuel filter (hate those damn fittings), and clean the MASS. Any other ideas? Thought I would start testing sensors but I would have to nearly check everyone as any of them could casue a lean code. I know a vacuum leak could be a cause as well. Just need some direction on where to start. As it is now I have no idea ans suspect everything.
Thanks

 

I would suspect fuel system first. Prob fuel filter. It went lean on one bank first and as the fuel flow became more restricted it finally hit both sides. could also be the o2's but I would never expect them to go bad at almost the same time. I think your plan is the best way to go. Lets us know how it works out

 

I HAD THE EXACT SAME THING on our 95 3.8! To change the rear plugs, place the front on ramps or jack stands and do it from below and behind the engine, very easy! I also changed the fuel filter, then cleaned the MAS with brake cleaner which cleared the problem

 

Also check the PCV valve hose on top of the Intake Plenum & at the rear Valve cover. I've seen these hoses crack & set those lean o2 sensor codes.

 

KYFordFreak,

Plugs are not the problem. When plugs go they do not cause a lean condition. For lean and rich DTCs check: FUEL SYSTEM, Excessive fuel pressure, Leaking /contaminated fuel injectors, Leaking fuel pressure regulator, Low fuel pressure running out of fuel, VAPOR RECOVERY SYSTEM. INDUCTION SYSTEM: Air leaks after the MAF, Vacuum leaks, PVC system, Improperly seated engine oil dipstick. EGR SYSTEM: Leaking gasket, Stuck EGR valve, Leaking diaphragm or EVR. BASE ENGINE: Oikl overfill, Cam timing, Cylinder compression, Exhaust leaks near or before the HO2 sensor.

Regards

Jean Marc Chartier

 

I have repaired several Windstars with 171/174 codes usually it is the o ring seals between the upper and lower intakes. not too difficult of a job they have redesigned o-rings at the dealer they are supposed to last longer.

 

Thanks for the tips guys, I will have to save and print those so I can check on them. Between dad which as 58 year old shadetree mechanic and myself an ASE certified parts man I should have it all fixed in one day, hopefully.
I know the plugs are not the lean code problem but with almost 100K it is more than well time for it. A slight miss can be felt anyways and fora second reason this fan is used 350-500 miles a week for moms trips to kidney treatments.
Thanks for the help guys, let you all know in a week or two what it was.