I continue to have issues with a p0171 code showing lean, but it goes off and on. I would say it'* on 70% of the time and off 30% of the time.

I have hit it with carb cleaner pretty thoroughly and noticed no difference in idle. In general, it'* never a rough idle, either.

Any ideas? I got the vehicle in August with very low mileage of 37,500 miles and now it has about 44,000. Other things to note:
--At the last oil change, it obviously had incrementally lost oil but I have not noticed any leaks (nothing on driveway and oil pan gasket is not showing a leak).
--Before the p0171 popped, I took the Buick on the only long trip since I got it in August, going 225 miles a few days before Christmas and then 225 miles back about 5 days later. Otherwise, almost exclusively used for commute to work (18 miles each way, mostly interestate).
--Finally, I'm adding a photo of some gunk that is spitting out from somewhere and appears to be aimed at the passenger side axle boot. It'* built up pretty good.
--This all seems to me to add up to possibly the upper intake manifold gasket issue. I don't mind taking a shot fixing that but obviously would prefer to be something less involved.

That looks like grease coming out of a cracked half shaft boot. If so, it is unrelated to the p0171 code.

One additional observation: I am noticing that, once fuel is about 40%, the code goes off. It then stays off until I fill up the tank, and comes back on within the first 20 miles of driving after fillup. Then it stays on until fuel tank drops below 40%. This pattern is now pretty consistent.

ust wanting to raise this up again. Here are the pertinent facts about this Buick LeSabre 1998 Limited -- which I got in August with 38,000 miles and now has about 45,000. I am new to DIY on vehicles and bought this in part because I want to learn and willing to try with so little invested (paid $2,400 for it).

1) For about the last 2,000 miles, ever since the only extended trip I have taken (250 miles each way over Christmas), the p0171 code showing lean bank 2 comes on and off -- 65% of the time on, 35% off. It always comes on within 5-10 miles of filling up the tank. It almost always disappears at about a 60%empty/40%full.

2) Last oil change, it was clear that oil is being lost somewhere but NOT from the gasket or drain pan. Seems to be in internal leak. Absolutely no oil drips onto driveway, parking lot, etc. So it must be leaking very lightly internally while engine is running and in motion.

3) Recently, the CHANGE OIL SOON light has come on and stayed on -- according to the manual, the computer does detect when oil has degraded. Although it was not the CHECK OIL LEVEL light, I did see was almost a quart low and so I have topped it off.

4) While I believe this could be the intake manifold gasket issue, I have sprayed and sprayed with carb cleaner and noticed no difference in rpms. In general, the car does not idle roughly -- seems very normal to me. No real issues at all, in terms of noticeable symptoms.

Appreciate any further thoughts on this. My other issue is that relationship with very trustworthy regular mechanic for years has been very much -- "you just do whatever it takes". So while certainly it'* possible for me to adjust the relationship to "diagnose for me and i'll fix it myself," his is not the type of shop where that'* customary.

Thanks.

How often do you change your oil?

Did you reset your oil monitor, the last time the oil was changed?

Did you fix your axle shaft?

As for the P0171, that is a mystery with the fuel level.......

Hey, there. Thanks much for responding.

I change oil every 5,000 miles. Last oil change was about 2,500 miles ago -- so seems to be losing about 1 quarter every 2,500 miles. I do not believe we reset the monitor then but I did so just now -- and the manual does say the computer actually checks conditions to determine if oil is degrading. I have reset the monitor now so we'll see if/when it comes back on.

Have not fixed the CV boot/axle issue. I realize that I need to -- planning to replace struts soon and it made sense to me to wait until I do that. Going to need to take a few days off and make it a long weekend of DIY, just in case I run into any trouble.

What is your fuel pressure when the light is on vs. when the light is off?
Could be a failing fuel pump.

I too recently picked up a low mile 98 LaSabre (34,000 miles) . Knowing it had the plastic intake manifold set up , I had it replaced before it became a problem . After it was fixed the used parts showed we got it just in time , in other words at 34,000 miles your days are numbered . Mine is rust free top and bottom , clean like new interior and IMO worth the expense to fix all the problems correctly . For what you paid you got one hell of a deal IMO , spend what ever it takes to keep it properly maintained . If you take care of it it will take care of you .

TheReaper!