My check engine light came on and I got trouble codes PO171 and PO174.
I read about the leaking valve cover problem and vacuum leaks.
I found Technical Service Bulletin 03-16-1 that outlines how to fix the problem.
But, I don't think that's what I have despite having all the symptoms.
I found some linkage, that I presume goes to banks 1 and 2. But I cannot find a picture or illustration in my Haynes manual or online that tells me what the little black box is. It's on the passenger side of the engine, just above the water pump, just below the valve cover. It don't see any vacuum lines goning into it, just electrical connections. But coming out of it are one metal link going to the front and one going to the rear of the engine block. It looks like some kind of butterfly valve.
My terminolgy my not be correct or the proper terms for the part.
This engine is in a 2000 Windstar 3.8L
Could anybody tell me what this part is?
The links BOTH fell off, the plastic connectors that held the links in place are long gone and I can't find a good way to keep the links connected.

Could this sensor(?) throw both banks lean code?
What is that part, so I can get new connectors and restore the links.



Thanks.

 

Im guessing thats the motor to the secondary intake runner flapps. I could be wrong, but doupt that would throw lean codes.

 

There appears to be an engineering number on the front of the box...post that here, and maybe I can help.

 

This thing only comes into play when you are at higher RPMs, when it opens a second set of intake runners for more power. It 'tunes' the intake length to better match the air flow required.
That said, you can get the codes if your O2 sensors are dead. They will throw a lean code if they quit working. They can be KILLED by silicone RTV sealants. Chemical reaction coats the honeycomb, I think. Anti--freeze will also send them to sensor heaven. If you have a multimeter, you can check their output. Try to remember "low lean" as the volts will be low when lean, and rise when the mix enrichened. The volts will fluctuate and that fluctuation indicates how worn the sensor is. An oldy will have slow 'cross counts' as it responds more slowly to mixture changes. FWIW.
tom

 

Thanks for posting. This all helps me make sense of my problem(s). The part number imprinted is AF2E 91559 AC. If you can find that part Bill I'll be indebted.
I'll try to check the output with my multimeter, when I get some free time. Thanks Tom. If this little black box isn't what's throwing codes then I likely have the standard vacuum problem or anti-freeze getting to the cylinder.
You know I was just pondering how grand this site really is. When I had a Jeep (briefly) and when I owned a chevy (it was given to me) I tried to find an online community like the one I found at fordtrucks.com, but there's nothing that comes close. Ford truck owners have it figured out. Thanks everyone.

 

Oh yeah, by the way just to throw some more details out there. On occasion the engine would stall, when rolling to a stop[cold weather/hot engine]. Since I read about it here, I started putting premium gas in the tank and no more stalling.
If i didn't have three jobs I'd have fixed the damn thing by now.

 

Thoughts off the top of my head: 1)check or clean your IAC and throttle plate to lessen stalling. 2) check using propane for an intake gasket leak. THe plastic manifolds can warp due to heat and lose their seal. Feed a small amount of propane thru a hose and let it out near the intake gasket joint. If the idle changes - you have a leak.
tom

 

IMRC its an intake manifold running control

 

Yep, they open at 3500rpm to supply more airflow at wide open throttle. They stay closed most of the time to provide better low speed torque. My Windstar has them.

 

Thanks for contributing. I've had a helluva time trying to track down those little clips. The mechanic I talked to called it the variable intake manifold. And they do what you said. I got the plastic clips installed, the codes cleared and the Windstar ran great, for almost a week. Only one trouble code came back, and I checked twice a week apart. PO174-bank 2 lean came back. Runs rough again, like before. I'm gonna look at the O2 sensor and check the fuel injectors next. I sure appreciate your help. This problem is taking forever because I have so little time when I'm not working.

 

check your fuel injecters on the driver side one may be unplugged causing a misfire or lean condition.

 

hi, try clearing all your codes and give it another try.good luck bokker.