My car set a code for the first time ever since I've owned it. P0171.
1997 Grand Prix SE with 3.8 N/A.
I have a concerning vacuum leak on the "T Fitting" on one of the vacuum lines that comes from the throttle body. One part of the T goes straight to the transmission. In between the T and Trans there is a reduced diameter fitting. The other side of the T goes (I think) to the fuel pressure reg. All molded fittings related to the T need to be replaced.
I think the "T" is one of the parts BillBoost posted a picture of here:
http://www.grandprixforums.net/missi...l36-44921.html
I'm not sure about the reduced diameter fitting or the one going to the fuel pressure reg. Anyone able to confirm?
The T is patched up with heat shrunk electrical tape and the reduced diameter fitting is rigged with a straight piece of vacuum hose because the reduced diameter fitting was destroyed. Somewhere between the T and the transmission there is a hissing vacuum leak.
The OBDII ticket Autozone printed says the following:
P0171
Definition: Fuel trim bank one condition.
Explanation: The powertrain control module uses the oxygen sensor to calculate the Air/Fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.
Probable Cause:
If bank one and two codes set together suspect fuel pressure or MAF sensor.
Oxygen sensor defective.
Ignition misfire-repair.
Fuel injector problem.
As for observable behavior, the engine seems to misfire mildly on one cylinder when idling. The misfire goes away a few minutes after cold start and doesn't occur at speed. Also, once in about every 100 miles when I'm giving it gas from idle say at a stop light, the engine will seem to just completely die for a split second then keep right on going. Both the misfire and the "sudden death" have been happening since I bought the car.
Right before the CEL came on I had driven 110 miles on the highway to visit my parents. After the CEL came on I drove 110 miles on the highway to come back home. I make this drive about twice a month without so much as a hiccup.
