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AUT0PR0, Auto Service Technician
Category: Car
Satisfied Customers: 130
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1995 Ford Windstar: Lx..ErrorcodesP0171and

Customer Question

1995 Ford Windstar Lx, 3.8 l engine.
Error codes P0171 and P0174 - system lean - both banks
This error only occurs after I start driving the car from a cold or cool start. It sets at about the time of upshift from 2 to 3 and accelerating. I reset the codes after pulling to the curb, start driving again and they never set again until the engine is off and cools down. Same thing happens upon starting out again. If I shut down for a few minutes and start out again, no codes.

Engine has 250,000 miles on it. Fuel pump is new - 40 psi at Schrader valve with pressure regulator hose disconnected and plugged. MAF sensor was replace 10,000 miles ago. Fuel pressure regulator replaced about 5,000 miles ago. Plugs are new, wires are not. EGR valve replaced about 30,000 miles ago, differential pressure sensor/controller was not. all four heated O2 sensors were replaces about 10,000 miles ago and did not change problem.

Any Ideas?
Submitted: 9 years ago.
Category: Car
Expert:  AUT0PR0 replied 9 years ago.
a common problem with these vehicles that causes codes P0171 & P0174 (system lean bank 1 & 2 ) is the rubber seals on the intake plenum isolator bolts. these are the bolts that secure the plastic lower intake plenum to to the intake manifold. they become hard and brittle and and allow vacuum leakage. I've replaced quite a few of them for the same problem. The ford part # XXXXX XXXXX They come in a package of eight and the repair normally takes about an hour and a halve to do.
Customer: replied 9 years ago.
Doesn't sound like we're talking about the same engine here. The throttle body is mounted to the intake manifold on four studs with a gasket between the manifold and the throttle body. The air filter is connected through a combination of plastic tube and two rubber hose, about 4 inches in diameter. The MAF is mounted in the tube right next to the air filter.

Your answer implies a vacuum leak somewhere but I sure can't find it. Vacuum readings are steady. The PCV was replaced a week ago and the crankcase vent tubes are sealed well.