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P0171 Stuff

SarasotaGTP

SarasotaGTP

New member
Okay so I introduced myself and a couple people said "I don't see any questions". I am about to fix that problem right now. Like I said in my intro, I had been lurking for a while and despite that I still decided to Buy a 97 GTP so I am obviously not the sharpest tool in the shed. Now I have read a ton of stuff on the P0171 code but don't know where to start on mine.

I have had the car for about a month and bought it from the original owner who was a retired 83 year old GM Line worker so the car has been maintained 100% with a TON of records. Remaining all stock and the only fuel that has ever been used being Amoco Ultra Premium and the only oil is Mobil One Synthetic. The car is 14 years old but in about as pristine a condition as I would imagine possible. Then I bought it and Murphy shows up.

I had just filled it yesterday and it had driven flawlessly up to pulling into the gas station but once filled and I tried to restart it, things were different. It sputtered and stalled. It cranks and starts right up but the rpms bounce for a second or two then it stalls again and this happens over and over. I towed it home and it sits in my garage now sad and waiting for me to figure out the P0171 mystery and I have no idea where to begin. It still turns right over but I did notice a stronger than normal fuel smell after it stalls if that might clue someone in to a good starting point. I appreciate any and all advice but I appreciate correct advice even more :th_winking:

On a side note, I tried to post a picture and could not get it uploaded. Size and format was okay so any tricks I need to know on that would be great because I know pictures before questions are always better but I will post one as soon as I can. Thanks again.
 


Isn't a 171 a vacuum leak?

Dry rot is super common on these cars so check all of the rubber "T" fittings around the blower/LIM/fuel rail/MAP/TB etc.
 
P0171 is "system too lean bank one" but from what I have read and even though I have read a lot I may not have read everything it is one of those ghost codes that people chase over and over till they go crazy or broke. I will start looking for dry rot but I really looked pretty hard prior to buying the car because of what I had read on here and it all looked pretty good. Oh well, I'll keep posting on here and looking for suggestions. Thanks
 
right but I have seen/read about people changing battery cables and this code going away and other various odd fixes that some how interact with something that this codes reacts to. That is why I used the term ghost code but I will hope that it winds up being something simple on this one. BTW Your write up on safe mods was awesome! So much info that it made my tiny brain hurt but awseome none the less.
 
Ok...find a scanner...or get an aeroforce scan gauge of sorts...watch the long term fuel trims (LTFT's)...if they are pegged at 16.4 then you have a vac leak for sure. Another way to try and find one...if the car is cool, start it...then spray around the engine bay with brake clean...if your idle jumps up...then you have found the leak.
 


Checked for Vac leak with brake clean and no idle jumping occured. Prior to that I looked at all the rubber and seals and did not find any dry rot or cracks at all. Took off TB checked and cleaned that as well as MAF and put back together. Stalling still there.
Tried the bent 85 tab trick and still stalling.
Removed MAF and stalling stopped but idles a little rough. Replaced MAF unit but left unplugged and idle improved to normal with no tach bounce. Threw a new code P0102 which I know is Mass or Volume Air Flow Circuit Low Input and assume kicked on since MAF was inactive at the time.

Sorry to ask what sounds to me even as an obvious question but should I just leave the MAF sensor (since it seems to be bad anyway) in place screwed in to plug that hole without plugging the sensor in or is there another option that is better? Thanks for all the help already!

I re-read my posting and thought I should clarify... I'm not talking about leaving the MAF forever just to try and be sure that was the only issue at the present time. I've read alot of times where people will replace this or that in trying to eliminate this P0171 and quite often it's like dominoes. What do you all think or better yet, what would you do based on the info I have provided so far? Thanks.
 
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Well now that the car seems to be running better than the other day... I now have 3 small spots of oil in my garage where the car was sitting. I Wiped them up and checked again and they came back Gonna try and chase these down and see if it is hopefully a drain plug and/or pan gasket. I took the car to a mechanic we know from church to give it a real good once over and he said the car was in great shape. I did have him do rear brakes and a lof about 4 or 5 days after we got the car so maybe plug or pan is all it is. I'm crossing my fingers.
 
Well like I said...I'd find a local to check the LTFT's on a scanner of some sorts...

If they are pegged at 16.4, then you've got a vac leak...somewhere.

Might also try to hook up a smoke machine to the intake to see if you can see it leaking anywhere.
 


Okay working on doing that asap. The man I know from our church has his own shop but he also teaches at a voc tech here and a local high school se it's not too easy to get in with him but it's worth it as he is very good and very honest. Thanks.
 
Okay I bought an Equus 3130 because I thought I may need it in the future in addition to now. The LTFT's are 16.4 like you said they might be. I had checked with the brake clean method and had no change in the idle. I had planned on doing plugs and wires and a fuel filter this weekend but what else do you suggest I try? Order of ease and or cost would be great. Sorry to be a PIA but maybe someday I'll be able to answer a question for somebody too. Thanks again.
 
Okay so I have done LIM/SC/TB gaskets plugs and wires and I had a bunch of strange stuff happen http://www.grandprixforums.net/car-almost-back-together-but-need-lil-help-please-56619.html now I have the car back home and it is throwing two codes P0171 again/still and P0748 which I am going to chalk up to the new PCM and the shift points that were altered in it.

My question is that with the MAF sensor in place and connected now LTFT are 16.4 car idles rough and sounds almost like a V8 with a 3/4 cam but drives like a bat outta hell for the short drive from the shop to home which was maybe 10 miles. If I unplug & remove the MAF the car idles good if I touch the sensor to the plug connectors the car will sputter and die. Is this obviously a bad MAF sensor or what do you guys think? Thanks!
 
It is a 97 and it has not had an in car tune as it is original gtp with only factory options but no aftermarket performance mods. The PCM that is in it now I got from GTPSHAWTY on here and it was one that Reptile did with the following changes which I just copy and pasted. This is the same MAF that I started with and had tried cleaning before and I've seen info that the MAF itself could cause the LTFT's to be off so I'd really like to blame the MAF for all my previous troubles as I could never find any VAC leaks but the LTFT's have always been 16.4

REPROGRAMMED 97 PCM BY REPTILE TUNED FOR 3.4 SETUP FOR 85 SHIPPED Speed limiter removed
- 3-1 and 4-2 skip shifts
- Transmission line pressure increased
- Shift points moved (5800-6000rpms)
- Fan turn on points altered:
- Torque abuse modes are modified to eliminate bog at launch
- Trans shifts are quicker
- 185 degree turn on
- 2 minute fan on at key-off\
- MAF calibration adjusted for proper operation and yea
- Removed “40MPH WOT lag”
those are the specs from reptile himself
 


Just wondering...^^but that wouldn't have anything to do with, Mike.

I had the wrong MAF tables in my '98 GT tune...and it threw a P0171...
 
I am not running a 3.4 but if I were to ever drop pulleys that is as far down as I would go to. I did not see any of those things as that big a deal and the fact that my LTFT's have always been pegged at 16.4 I am thinking my MAF may have always been off or at least I am hoping it's that simple at this point. I never talked to Reptile direct about this specific stuff and I am not blaming him or Shawty at all. If there is something wrong it is 100% on me

I hear ya Shawty and I actually found a pick n pull place not to far from here I am gonna go try and grab a few things tomorrow or Wednesday. I guess they have a few cars in there and they supposedly have roof rails and spoilers on a couple of them and one even has a "different style hood" is what the guy told me so I wanna go check it out myself
 
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