failed emission test/ p171 &174

[diveman1669]

hi.

while i am mechanically inclined - my chilton's & me... i have been reading the posts on the tcb 03-16-1.

Is this something that FORD should fix?? where can i find the details of this bullien. My car is a winstar 96. Is this covered under this TSB. Do i call ford direct or any dealership.

It looks like a really big job for my year/model 3.8 to pull the valve cover off.

any help would be appreaciated.

thanks...

P.s. this is a great website!!!

[DRW1000]

I don't believe that TSB applies to a 96--

If you know you have the 171 and 174 codes then look for a vacuum leak somewhere first. Look somewhere common to both banks.

[diveman1669]

thanks for the reply.

actually i just found a tsb in regards to the 96 - discussing a mass air flow sensor..... i am reading more, but i also will check on the vaccum lines as you suggested..

thanks!!

[DRW1000]

Originally Posted by diveman1669

thanks for the reply.

actually i just found a tsb in regards to the 96 - discussing a mass air flow sensor..... i am reading more, but i also will check on the vaccum lines as you suggested..

thanks!!

I am not familiar with that tsb or 96s in genereal but the MAF could certainly cause these same two codes. If you determine the MAF to be out of range try cleaning before buying a new one.

[wiswind]

That TSB is for 1999 and newer windstars.
They went to a different, less reliable, upper intake manifold in '99.

I would clean the Mass Air Flow (MAF) sensor with non-residue electronic cleaner. I have detailed pictures of the MAF in my pictures, which the link in my signature will take you to.
Behind the screen in the MAF unit, the end that faces the air filter, you will see a plastic bar that goes across, there will be a hole in one end of it. On the opposite side of the bar, facing the throttle body there is another hole.....on the opposite end of the bar. The principle is.....that air flows into the hole facing the air filter, and out the hole facing the throttle body.
There are 2 sensors inside the bar......you want to spray the electronic cleaner into 1 hole.....and have it flow out the other......flushing away any dust and / or dirt that may be causing problems with the sensors.

In the flexible part of the air passage from the air filter / MAF is another thermistor.......it is the input air temperature sensor. It can be cleaned with the same electronic cleaner. Make sure that the stiff plastic hose that goes from the front valve cover to the back side of that flexible hose is connected into the flex hose.

Also, check the flexible elbow that is on top of the upper intake manifold......next to the throttle body. Mine developed a crack on the inside of that elbow. Also follow that line all the way back to the PCV valve, and make certain that the line is intact....nothing leaking.

There are a whole bunch of vaccum line connections to the back side of the upper intake manifold. Any one of them can be loose and leaking. If one is fully disconnected.....the function that it is for will not be working....which should give you another code.
The exception is the line for the Heater/Vent/Defrost selection. The default position for this is defrost.

Check the vaccum line that goes to the top of the fuel pressure regulator....which is on the passenger side of the fuel rail.

In any case, the cause is a vaccum leak....NOT defective oxygen sensors.

If you can accellerate OK, I would not think that fuel flow is the cause of the problem.