96 Windstar lean code bank 1 and bank 2. Please Help

Hi I’m new here, my name is Tom. I’ve been browsing the site and there seem to be some very knowledgeable people here so I was hoping I could get a little help.

I have a 96 Windstar 3.8 with 65K. The Check Engine Light came on. I cleared it and it came back on. I had it scanned and it said lean bank 1 and bank 2. I did some research and I read that the most common problem for this was probably the MAF. I took out the MAFS and cleaned it put it back in and it didn’t seem to help. I then bought a new one put it in and again it didn’t seem to help.

The cars idle has been bad since the light came on. Upon start up it will shoot to 2k rpms and then fall to 1k rpm and surge back and forth from about 900 rpms and 13K rpms. Sometimes it will even die.

Also when I had the intake apart the rubber baffle right in fort of the throttle body had a good size pool of oil in. Not a build up of slug but a big pool of fresh oil that appears to be coming from the hose that goes from the vale cover to the intake baffle. Should I be concerned about this. Could this be part of the other problem.

Any help would be really appreciated . Thanks in advance.

I don't know where you did your research but 95% of the time, P0171/174 (lean bank 1/bank 2) is a vacuum leak. I would bet money that either you have a bad PCV line from the valve to the intake, or a bad PCV valve itself (which would account for the oil pooling in the intake). Also, I think you have the wing-style upper intake, I have seen some of these leak similar to the plastic bubbles that were used later.

I agree with yotermanic. The most likely cause for a the lean codes (171/174) are leaks in the intake stream or more fundamentally air in the intake stream that did not get properly reported to the PCM by the MAF or that the PCM "thinks" it added the correct amount of fuel for the reported volume of air but the exhaust is determined to be lean due to the report from the 02 sensors. . This could be the MAF, it could be low fuel pressure too (but not low enough to cause misfires). The 02 sensors could be faulty but this is rare AND the fact that you have both codes would imply that both failed. I would check for leaks first.

The one clue you have is that you have lean reported in both banks so the problem is common to both. There are isolator bolt problems for many Windstars but they do not apply to 96s.

Thanks for the feedback. I know this may seem like a stupid ? but where is the PCV valve and how would I replace this.

Any other ideas.
Thanks

Thanks for the feedback. I know this may seem like a stupid ? but where is the PCV valve and how would I replace this.

Any other ideas.
Thanks

Hi
the pcv is located on the rear valve cover. If you start on top of the throttle body and follow the vacuum line that attaches on top of it aft, it will lead you to the PCV sitting in the top of the valve cover.

The hose that goes from the top of the upper intake manifold, next to the throttle body, goes back to the rear valve cover. This is where the PCV valve is. There are a couple of lines that tap off of the vaccum line to the PCV valve.

I have a Motorcraft brand of PCV valve, and still have some oil as you describe.
Aftermarket brands can cause too much flow, and cause more oil.

The connection of the PCV vaccum line to the top of the upper intake manifold is a flexible elbow. Mine developed a crack on the inside of that elbow, which would be a cause of a vaccum leak.
Also, give the whole line a good look and feel over.

There is a line that goes from the passenger side of the front valve cover.....and plugs into the back side of the big flexible hose that goes from the throttle body to the MAF / Air cleaner unit.
Make sure that this is plugged into there, or that is another source of vaccum leak.

There are a number of vaccum lines that connect to the back side of the upper intake manifold. You could feel around back there and make sure that they are fully seated.
Be careful, as it is easy to bump them loose.

Also, Check the vaccum line connection to the TOP of the EGR valve, to the TOP of the fuel pressure regulator (passenger side, on the fuel rail), and to each of the IMRC actuators (also on the passenger side,,, next to the fuel pressure regulator).

Check to see if you can adjust the heat / AC controls to have the air go to the floor, and to the panel vents.
The air selection is vaccum controlled, with the default being to the defrost position.
If you cannot select the airflow away from the defrost, then you will need to follow that path, as that is likely your vaccum leak.
That vaccum source is also from the back of the upper intake manifold, to a black plastic "box" that is a resevoir, which is mounted on the passenger side inner fender.....near the firewall. A vaccum line goes from the box, into the passenger compartment, to the controls. There are some silver "bulbs" with vaccum lines going to them that you can see if you look up under the dash in the passenger compartment.

If you do have a fuel flow / pressure problem, the PCM will not set a code for it.
This is because fuel flow and pressure are not monitored or measured.
However, the problems caused by this may set a code.
I would expect fuel flow problems to be more of an issue at higher engine speeds and loads.
I would expect a vaccum leak to be more of a problem at lower engine speeds, worse at idle.
This is because the air entering at the leak would be a greater percentage of the total air actually entering the engine at idle as compared to when you are moving down the road.

Thanks for all the help and all the great info. I'm gonna go over all the lines this weekend.

Thanks again Tom