Hi all, I have read LOTS of post here regarding tracking down and curing the evil 171 and i need more ideas. Excuse me if I get something out of line here these dang cars with computers get me! So far i have changed the air filter - not a K&N (it needed one bad), cleaned the throttle body, pulled and cleaned the MAF sensor, checked the grounds on the battery and the block side, verified that the plug wire was not touching the O2 sensor and cleaned/verified that the PCV was fine. I did do some searching for a vacuum leak but was unable to find anything.

While i don't feel it is related i did replace the water pump and belt before the 171 popped up.

Tonight i changed the fuel filter but only test drive it for a few minutes.

Suggestions / thought ?

Greetings from Corvallis (don't overlook the WCBF link in my signature, big meet coming up in OR)

Can you put your year and trim level/model in your signature by editing your profile? We need to know what you have. Obviously OBD2, but that code could cover a number of combinations under your hood.

The P0171 is hard to track down. We've seen both electrical and mechanical causes for it. My first question would be how old is the O2 sensor (front, in the rear manifold)? If you don't know, or you know it'* over 50k, just replace it. They get tired about that point. While this may or may not fix the problem, it'* a good thing to take care of regardless.

The best way to track down a vacuum leak is to spray carb cleaner on each vacuum connector at idle, as well as around the base of the supercharger/upper manifold (depending on engine) and around the LIM/Head interface, as well as the fuel injectors where they go into the LIM/Heads (again depending on engine). If you find a leak, it'll change your idle speed slightly as the carb cleaner is sucked in and combusted.

We've also seen battery cable corrosion cause this code (believe it or not). Disconnect both cables from the battery and pull the rubber boots off (you won't see the corrosion without pulling the boots). What do you see in there?

Can you pull the front three plugs and take a good closeup pic of them?

take wills advice and soon enough you should be good again

The sensors are the originals and the car has 87992 miles on it. What brand of sensor is recommended? Bosch=bad? Do I really need to buy the sensor socket to replace them or will a flare end work? I have tried the test for vacuum leaks but will get another can and try again. As far as the front 3 plugs, I will pull and take a look at them. I would assume that they should be on the whiter side of the shade since it is "running lean".

TIA

AC Delco sensor is best. www.rockauto.com and use our discount code in General Chat.

You don't really need the sensor socket up through '99. There'* enough room to get a large adjustable wrench in there. It may help to have the rear manifold SLIGHTLY warm to help release the sensor. The new sensor should come with anti-sieze already on the threads.

Ideal plugs would be a light tan color. Lighter would indicate hotter/leaner. I suspect you'll find light tan, and the lean bank is a false code, but that may not be the case. Just my hunch.

Another thing to look into in the very near future is this:
http://www.bonnevilleclub.com/forum/...e=article&k=38

And this:
http://www.zillamotorsports.com/DEX

I doubt either is causing your problem, but these are major issues you'll want to address in the near future, especially with the age of your car.