FAQ: P0171 Lean Condition

Usually right after taking off, but not all the time. The guy said there were two identical codes. The car kinda falls on its face but always comes right back and keeps going. Pretty annoying having to deal with for 1k miles. I saw the thread on the MAF. Any other things I should check or change?

CHECK YOURE FUEL PUMP FILTERS!!!!!!!!!!!

Filters? I know of the fuel filter underneath the car. Is there another?

YES! If you have never put in a new fuel pump,then youre INTANK fuel filters are probably gone. the only way to find out is to remove the fuel pump from in the trunk area and inspect the 2 filters attached to the fuel pump itself.If they are torn,and chances are they Are,then thats your prob.Mine were dog gone and dead. As a consequence so was my pump,a torn filter will allow all manner of grit and dirt in the pump and it will start to fail.mine had been failing for years.
Check it out. if you live back east then chances are your fuel pump lock ring is shot.If it is you will need to order another as removal of a rusted one will result in broken lock ring.

Oh, I gotcha. The fuel pump is only about a year old. I'm going to change out the fuel filter tonight.

Ok I'm starting to get extremely frustrated with this code and nobody seems to have an answer. I replaced the supercharger with a fully ported one and a 3.6 pulley,new belts, 180 t stat, al104 platinums, autolite wires, and this po171 lean code started popping up. This car needs to go through emissions by December so I have about a month to figure this out. I've also gotten a p1406 but this was resolved with a new egr. I've changed downstream o2, fuel filter, vacumn lines in hopes of getting rid of this code, ses light seems to turn on at a stop or when you blip the throttle, my dad checked for leaks on the intake with some staring fluid and found one. Tightened the bolt and it went away until just now I put the car in reverse to back up and it set the code. Maybe a better vacumn diagram could help as I could have missed something, the one on the engine bay isn't much of a help.

What about upstream O2 sensor? That's the one that reports the lean code. Downstream sensor only monitors cat converter.

Have you cleaned the MAF sensor?

Sorry I meant upstream and yes I cleaned my maf sensor no luck.

Ok I sprayed some carb cleaner on my egr tube and rpms jumped a little are the tubes the same on n/a cars? Also my maf readings seem low at idle will n/a mafs work?

h20man wrote:

Ok I sprayed some carb cleaner on my egr tube and rpms jumped a little are the tubes the same on n/a cars? Also my maf readings seem low at idle will n/a mafs work?

The EGR tube is the source of your vacuum leak. That's the reason for both the lean code and the MAF reading being low - less air is going THROUGH the MAF, as it is being sucked in at the vacuum leak.

I believe NA motors have the same EGR and tube.

I need to check this on my car then I thought this lets gas out the engine

I'm gonna change the tube cracked or not its most likely the o ring on the end that's chewed up, hopefully that fixes it is there a possibility its the fuel pressure regulator causing a p0171?

h20man wrote:

I'm gonna change the tube cracked or not its most likely the o ring on the end that's chewed up, hopefully that fixes it is there a possibility its the fuel pressure regulator causing a p0171?

On your first start up in the morning does it take a long time to start up ???

No it always starts right up even at 30 degrees here in connecticut

h20man wrote:

I'm gonna change the tube cracked or not its most likely the o ring on the end that's chewed up, hopefully that fixes it is there a possibility its the fuel pressure regulator causing a p0171?

p0171 is a lean condition. You are lean because air is getting in after the MAF (vacuum leak), so it's not adding fuel to match. The FPR is also vacuum controlled, so fix your vacuum leak (EGR tube) before looking any further. It's entirely possible you have multiple vacuum leaks, but start with the easy one you found.

I sprayed the egr the tuben fittings mines spiked too but its no gaskets made for that

I'm ordering a tube now is it me or do these cars run crappy with the ses light on?

h20man wrote:

I'm ordering a tube now is it me or do these cars run crappy with the ses light on?

That's a stupid question. You have a legitimate problem that directly affects the way the vehicle runs. Of course it's going to run crappy with the SES light on..... 

Lol no comment ... I miss the old days when you put some lead in it and goes... btw where did you find the tube at?

Sorry didn't know there was such a thing as a stupid question... I'm used to the simplicity of obd1

Not all problems that trip the check engine light to come on will make a car run crappy. I personally would rather diagnose a CEL on a crappy running car than one with no symptoms. When you repair a problem or replace a faulty part and the car runs better immediately, you can usually be confident the CEL won't come back on after you clear it.

If you guys are having trouble sealing the EGR tube, this might help:

https://rivperformance.editboard.com/t10072-write-up-egr-tube-gasket-fix-for-tick-tick-tick

When mine was leaking, it was heard as a ticking sound under low-RPM throttle, and engine surged in neutral when idle, but never got the P0171 code.

AA wrote:

If you guys are having trouble sealing the EGR tube, this might help:

https://rivperformance.editboard.com/t10072-write-up-egr-tube-gasket-fix-for-tick-tick-tick

When mine was leaking, it was heard as a ticking sound under low-RPM throttle, and engine surged in neutral when idle, but never got the P0171 code.

wow that's a great idea, I wonder if I could do the same to the end of the pipe that goes into the lower intake manifold?

Well I sprayed the egr its self it spiked I sprayed the manifold where the egr met it spiked ... took it to the shop the guy told me my gaskets are wrong for the car lol... I'm tired of paying at the pump already

Johnny a serious question - do you do any of your own work on the car, or are you having the guy at the shop do it for you? Is he familiar with the 3800s or is he guessing on a lot of this?

You can save a lot of time and money by dealing with this stuff either yourself, or with a mechanic who is familiar with "GM's way"...

Ask around the local retirement park where they like to get their Buicks serviced. Where my mother is in FL they will tell you all about this guy who used to work at a GM dealership and got fed up with them and went and started his own shop. Take it in there and they will find and fix the problem(s) in one shot, just about every time. He knows who his customers are and he gets their repeat business because he and his guys do it right the first time and doesn't charge what he could... that reputation goes a long way.