98 GP GT 3800 with P0171 off and on?

**Fritcr** · 01-27-2011

I have done some searches and found that most people say it is a vac leak. Let me give you some backgroud. I was driving home a few months ago and the car just started bucking and cutting out and the check engine light came on. I got it home and took it in the next day to my mechanic. (I usually do alot of my own work but have had some medical issues the past several months so just getting to work was about it for me) He called and said it was p0171 and p0101 and said it needed a new MAF sensor. I told him to put one on it. I picked it up and it ran pretty good but not just right. It has a bit of a hesitation when taking off and also it does not always idle real smooth. Anyway, the light came back on and I dropped it off again. Mechanic did a smoke test on it and said he found a small vac leak. Said that should fix it. It didn't, it still comes on every few days or so...stays on for a couple of days then goes off for a couple. I called but he said he didn't know and that I should drive it until it gets worse so he could find it. I don't want to do that and I'm feeling better now. After a few nights of rest I can probalby dig into it some...maybe this weekend. I will check myself for vac leaks, corroded cables, and the EGR tube. (this is what I have found with my searches). My question is...if he did a smoke test shouldn't have any of this showed up except for the corroded cables?
Also, it makes me wonder if I got a bad MAF since my car was running good and then suddenly went wacky and would hardly run at all. Then the replacement MAF got me running pretty good but not just right?
sorry, I'm rambling...just random thoughts. If anyone has any imput I would love to hear it. BTW..I also have access to a scanner that reads different levels and such but I don't know what I"m looking at. LOL
Rob

**nikiyo88** · 01-27-2011

Sounds like my issue. replaced my ICM and Crank Sensor. Fixed it but now it sounds like a vacuum leak.

**mikedinthecity** · 01-30-2011

yes i would say that lean code indicates some type of vacuum leak. the fact that its a fuel trim lean bank1. all vacuum is ran somehow through the intake. it could be lower intake manifold gaskets, throttle body gasket, vacuum lines, sensors that are run by vacuum, plastic plenum. that egr tube does get hot where it plugs into that plenum, but ive seen that cause the engine to vapor lock, which car gor repaired and ran like new. good luck let us know what you find.

**Austins01GP** · 01-30-2011

My buddy had the same code turned out to be the y fitting coming out of th throttle body was cracked bad picked one up from a junkyard and it's perfect now!

**Fritcr** · 02-14-2011

Ok sorry for the long delay but I did check everything I can think of for a vac leak. I also took off my TB and cleaned it all up and put a new gasket on it. I took the tube off for the egr that goes in under the TB...it does not have a crack or hole in it. The Y fitting on the intake is fine. The pcv valve is fine and I cleaned it all up and put it back in. (with the O ring). I cleaned the battery cables...(someone suggested that) After all of this it ran great with no codes for a couple of weeks and I thought it was fixed then my wife took it to town and txted the light was back on. (my car does not like her cause she talks BAD about it!)
So, I don't know what else to check. I don't see anything else it could be. I did tighten down the plastic upper intake thing a bit. It didn't seem very tight. A few bolts I could not get too. I also checked the line from the fuel pressure reg and it does not have gas in it.
Any other ideas?
Rob

**BillBoost37** · 02-14-2011

Rob..at this point it's likely the maf or your girl. It's your choice which one to replace first to try and cure the issue.

**01gpgt01** · 02-14-2011

Keep on looking, Vac leaks can be a PITA to find. If you can scan Idle air control counts you could see if you indeed do have a vac leak.

**Fritcr** · 02-14-2011

I have access to a scanner that shows all kinds of information but I don't know what they should be. It can read and save all these values but I don't know what it means.

I would replace the girl but she would beat me to death so I best keep her I guess. Might try another MAF...it should be under warranty.
Otherwise...I will keep looking for leaks I guess. I can't keep taking in and getting charged for crap I have already checked/fixed.

Rob

**Fritcr** · 02-19-2011

Swapped for a new MAF and that did not fix it. Light came on later the same day. It is back off now.
The upper "plastic" intake bolts seemed very loose to me...I tightened up the few I coudl get too...do you all think that could be the problem? Should I take it apart enough to tighten all of them?
Thanks for all of the advice.

**Fritcr** · 03-21-2011

After a time of "not messing with it" I have started back up on my p0171 code. I got mad and took it to the stealership. They just called and said it needs a fuel pump. Said the psi at idle is 35. I will pick it up in a few. Can this cause the p0171 code and also...does my car have the trap door? It is a 98 GP GT with na 3800.
Thanks so much for all of the help!
Rob

**01gpgt01** · 03-21-2011

Ive never seen a Fuel pump set the p0171. They usually work or dont, No inbetween. 2002 Grand Prix GT 3.8 Fuel Pump Installation | eHow.com Ive swapped mine out in 10 min. There is a access door behind the rear seat.

**The Guz** · 03-21-2011

Found this. You may want to consider changing your fuel filter before you do the fuel pump.

OBD-II Trouble Code: P0171 System Too Lean (Bank 1)

Causes
A code P0171 may mean that one or more of the following has happened:

•The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor.

Possible Solutions
Possible solutions include:

•In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
•Inspect all vacuum and PCV hoses, replace if necessary
•Check for a dirty fuel filter and proper fuel pressure

**Fritcr** · 03-23-2011

They checked the fuel filter and said it was fine. (I changed it last year)
After they messed with it when I picked it up...now my fuel pump is really loud and I can hear it hissing. I never noticed it before.
Anyway, if I need to change the pump...has anyone used the aftermarket pumps off ebay or are they just junk? O Riley's wants $253 and I can get one off ebay for $68. I wouldn't probalby consider the cheaper one but I might be getting my mom's BMW soon so I don't know how much longer I will have the GP. Unless...of course my daughter wants the GP but has no job...lol
I don't know what to do...i'm trying to run most of the gas out of it now so I can change the pump if you all think that is what is wrong. The light came on again today and it sometimes spits a bit at idle or taking off. It is a sick little GP :-(
I like it but a chance to get moms 540I is to good to pass up.
Rob

**BillBoost37** · 03-23-2011

Yes a weak pump can cause the issue. The pcm tells the injectors to perform at a certain rate based on flow and supply of fuel. If fuel isn't there, the injectors aren't pushing as much as they should.

**01gpgt01** · 03-23-2011

I went with a used replacement from Morad parts. It was 60 shipped with a 90 day warranty. 3 years later no issues.

**Fritcr** · 04-19-2011

Still working on this issue as I can. I have now taken it to the dealer for a look and they told me my fuel pump was weak so I put a new one in but it does the same code right away. The problem is getting worse too. When you start it...esp. when warm it "lopes" like it is going to die but never does. Usually a little rev of the rpms makes it stop but sometimes it returns after a few minutes of idle. It never seems to idle funny when in drive that I have noticed much.
By the way, the new pump broke my gas gauge...I have already taken it out and sent it back for warranty. They sent me the same pump again. I took a chance they fixed it and put it back in and NOPE only works on the lower half E to 1/2 tank or just over. With a full tank it only shows just over 1/2. Very frustrating.
Any more ideas on the P0171 code? (the light seldom goes off now)
Rob

**suzie** · 04-19-2011

I;m thinking MAP sensor but that's only 1 of like 70 possibilities

**Fritcr** · 11-15-2011

I know this thread is kind of old but I am still having the same issue. My daughter now has the GP. It still has the P0171 code that come and goes. I bought the BMW and that thing is a worse mess than the GP. Anyway, she has a job and is planning to go to college with this car so I need to get back to it and fix it. It still is hard to start sometimes esp when warm. It also seems to idle kinda funny...it sort of lopes or something after it finally starts. It is NOT missing but just don't want to get going. Once you rev it a bit and get it in gear it runs great. Not so great on gas mileage at about 21 blended but I can't find anything wrong with it. Oh since last post I also repalced that plastic t thing and some of the vac lines on the intake just in case but it did not help. New fuel pump in and gas guage works pretty well...not perfect but she is used to it now.
I would take it back to the mechanic but he don't seem to know anymore about what's wrong with it than I do. My dad has a fancy code reader thing but neither of us know how to use it. It does all kinds of test etc. I might try to find some time and bring it home...do some reading and see if I can get some fuel number and such from it. Maybe someone on here would know what they mean.
Rob

**BillBoost37** · 11-15-2011

The loping has me wondering.

Could be a dirty TB or something else silly causing the lope type issue you mention.

As for the 171.. you say you cleaned the battery cables. Did you pull the boots off the ends (pull bolt out and the ends slide off) and take a look for corrosion going into the cables?

**Fritcr** · 11-15-2011

yeah I don't know what is causing the loping...it straightens out pretty quickly but it feels like it is going to die. Never does that I know of but it is weird.
I did clean the cables by cutting the boots off and cleaning everything really good. It made no difference. I did not see any corrosion going into the cables.
I also took the TB off and cleaned it really good and put a new gasket on it. Cleaned the MAF and Idle air control.

I have a weird question...what is the thing that is an electronic sensor on the top of the fuel pump? In the mist of all of the gas gauge problems I have had that fuel pump out like 400 times...well ok maybe it was like 4 or 5 but anyway I don't know what that thing is. What does it do?
Rob