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Hi I'm new and have a p0171 code, can you help?

falconjohnd

falconjohnd

New member
Just got a 98 GTP yesterday and have this code. I believe vacuum is tight because I tested with TB cleaner. Car doesn't have a diagram so I may have missed something. MAF looked fine but I cleaned it anyway, put in new PCV and Air filter. Previous owner says it was a recurring problem and he's a car guy you should have seen the ponchos in his garage. I have a scanner what data is in the norm? I also dropped a bottle of techron in the tank but that will take some time to have an effect. car runs really well despite code.
 


Re: p0171

First hello. Second try googling the code and see what it says if you dont have the book with your obd2
 
I'd fine someone with a scanner/tuner to see what your LTFT's are. If they're +16.4 or what not it's probably a vac leak. It could also be your o2 sensor. I'm willing to bet it's a vac leak though.
 
P0171 is bank 1 lean code. Lots of stuff written about this code. I will run the diagnostic again today now that I know what to look for. Any clue where I can find the stats for all the measurements? LTFT is there and some other stuff but without knowing what numbers to look for it's kinda useless. If it is a vacuum leak other that throttle body cleaner what else can I use to check? Also any idea where I can get a diagram?
 
If you are getting an LB1, your fuel trims are a given. It's not a question, it's a given.:th_winking:

First stop is pulling the EGR tube. Don't waste the carb cleaner on it. You can't typically get any reaction from it, yet it can leak. Pull back the retainer piece that sits at the LIM and hold the tube to the light. Got a crack? Most do. I have one I'm going to get pictures of very soon. Just got it this weekend on a cam swap car. These tubes are such and issue, I stock up from a JY on them.

Second stop, It's not the O2, the O2 is what reads the condition and tells the pcm about the lean issue. It might be a maf issue, never seen an O2 cause this code though. Because if the O2 fails, there are other codes that will get tossed.

Battery cables. If they are corroded, dirty etc.. this can cause it.

TB gasket.

For more on this fun and exciting code that can plague you for months, search on P0171 and my name.

I bought a ton of stock in this code.
 
Will check that tube if it ever stops raining. I know it's not the O2 because that's just the messenger of the bad news. Previous owner swapped the MAF already, I cleaned it again and so far after 80 miles it has stayed out. MAF didn't look dirty to me.... Wouldn't a bad TB gasket have showed up with the cleaner. should i open it up anyway and give it a good cleaning. One more Q. Would lower grade gasoline trip this light also?
 


Any vaccum leak would have to be perfect condition to pull in cleaner. Maybe it doesn't. Not sure. But I've found these areas to be issues in the past.

The tube. Uh..there are two. One is part of the EGR pedestal though.

Low grade shouldn't. It should only cause you to be on the low octane spark tables which would leave you wanting power from the motor.
 
Bill, from what I'm reading here you are a bit of a legend..... Appreciate the advice, I ordered up a tube and a gasket for that and a TB gasket and should all be here tomorrow. Cost about $30 all together. I'm gonna jump in this weekend. I'll definitely keep you posted. thanks again.
 
Changed EGR tube and the tb gasket code came right back even without all the monitors set. What's next to look for. Is the MAF bad? how do I test it?
 
P0171 back again!!!!

New EGR Tube, new TB gasket, new pcv valve, new fuel filter and a dose of techron to clean up any dirty injectors, and new MAF sensor and the code keeps coming back for more...... aggravation that is! If it's a vacuum leak it's a real small one because carb cleaner isn't affecting the idle. I don't believe it's the fuel pump car runs very well. Anybody got something new?
 


Bad vacuum boots on the manifold lines can cause this. It doesn't take much of a leak to cause this code to pop up from my experience. If the EGR tube wasn't the culprit, then I'd investigate the rest of the lines, even the o-ring that seals the top vacuum port on top of the supercharger.
 
I will check these boots next. Not sure where that port is that you mentioned. Is it that black plate on top that's bigger than the one that covers the PCV? Battery cables are clean and non corroded. The thing that is getting me is that even with a new MAF (did that Friday) and the other things I have done so far the the light comes on even before all of the monitors have reset from clearing the code. It stayed off for about 100 miles or so after the MAF was changed came on Saturday went off on Sunday came back last night. There are no driveability issues that I can tell and I've put about 700 miles on the car since I got it a week and a half ago. I think it's messing with me......
 
As far as the fuel pump goes... so far all the parts have been relatively inexpensive gotta believe this is not a cheap one so I'd like to know for sure before I buy one.
 


The way to do that would be to check the fuel pressure. If it's low either the regulator is bad or the pump can not keep up.
 
Sorry for this question but; How? Is there a gauge for this or use the readings from the scantool? Then I have to ask why wouldn't both banks show a lean code.
 
Ahhh very good questions.

The reason you only show a bank 1 code, is because we only read the precat and post cat exhaust in one place. Therefore it considers our mixed front/rear exhaust to only be one bank. If we had an O2 sensor in the front exhaust and rear, then they combined with a Y pipe, we would have two banks. But we don't. So there is only one bank to read O2 info from.

A fuel pressure gauge is about $30 at the parts stores. You hook it to a fitting on the fuel rail to read the pressure.
 
Okay..... Two rails so two fittings and two readings yes? What's the acceptable range? And if one's good and the other bad could it be a bad rail rather than the pump?
 
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