The check engine light came on in our 02 Gr Caravan w/3.8. I was out of town so the wife took it to the dealer. They supposedly ran all the tests and tested all the sensors, etc and the light is still on. They said it had a trouble code P0171 #1 side fuel system is lean. They asked where my wife bought gas, she told them, they said it tested out 15% ethanol and that was the problem and the light would go out. I come home, drive the van 250 miles, put plugs, wires and a PCV valve on it and drive it back 250 miles. Light is still on. I had the codes pulled at the local Auto Zone and then they cleared them. Came back on. Did it a second time and it came back on again. Now What???

Usually that code originates from a fuel delivery problem. Bad pump, plugged filter (how old is it?). To start I would do a fuel pressure test under all conditions.

Could be a vacuum leak in your plenum gasket as well.

Thanks guys!!! I just replaced the fuel filter when I did the other work. A couple other pieces of info - the van is sucking down gas like no tomorrow. I'll check the plenum gasket and see if I can get my hands on a fuel pressure tester. On the intake plenum, is this the same as the intake manifold? I believe that may be two pieces. Is it the gasket that goes between the top and bottom? One other thing is you can smell the unburned gas, if that makes sense. It doesn't smell like fuel but has a very distinct smell. My son has a 91 Cougar and I'm working on it due to what I believe is plugged cats. It smells the same way.
Thanks again!!

As 10sec440 said you should check fuel pressure under load
I would highly doubt a plenum leak, while yes a leak could cause a slightly lean condition, you will also typically see a "target idle not reached" DTC in conjuction with this due to too high of idle from the vaccum leak.
There are several things that can also cause this,
Map sensor calibration: this can affect correct barometric pressure readings on "key on" and throw the whole fuel curve off
O2 related stuff: non working heater , sluggish operation, blah blah blah
Coolant temp sensor calibration: if it is reporting that the engine is hotter than it really is.
There is alot of other crap that can cause it but these are the most common causes.

It would help greatly to know what the bank adaptives look like but without a good scan tool you will not be able to access it. If the fuel pressure is either low or lacking volume BOTH banks will be out in left field.

Personally I would also check the fuel pressure under load, and the upstream O2 to make sure it isn`t lazy, but that is just my opinion.


Rick