P0174 and P0171 again
Thread Starter
TECH Enthusiast
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Joined: Nov 2006
Posts: 605
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From: Pineville, LA
P0174 and P0171 again Ok I pin pointed the problem I think. The codes say bank 1 and bank 2 are too lean. I get those codes when my gas gets below half a quarter of tank. It doesn't run bad. When I shift it kind of hesitates before the throttle kicks in but you can barely tell. So I fill the car back up (haven't yet) and the codes go away. Not enough fuel pressure? Any suggestions?
TECH Apprentice
Joined: Apr 2005
Posts: 319
Likes: 1
From: North Carolina
"Does it at below half or quarter of a tank" Makes me think it may be a fuel pressure issue. I'd check the pump and replace the fuel filter. Where I get that is that maybe with a full tank, the weight of the fuel may be enough to keep the pressure up or push it through a clogged filter. Once the fuel burns off, maybe the pressure isnt there and its getting enough fuel to run, but also throw a code. I replaced my fuel pump when it started making funny noises. No pressure issue, but I wansn't waiting around to let it go bad. PLUS it was an excuse to upgrade.
Staging Lane
Joined: Dec 2005
Posts: 51
Likes: 0
From: Denver, Colorado
I had the exact same problem about a year ago, but it was only under very low cruse RPM. However, the problem seemed to be connected to new K&N air filter that I put on replacing the stock paper filter. I live in Colorado where the air is thin anyway. I know that it doesn't make sense because K&N are suppose to flow better, but that's what happened. I sense cleaned the MAF and TB with some sea foam and I haven't had any problems since.
Good Luck.
Good Luck.
Staging Lane
Joined: Dec 2005
Posts: 51
Likes: 0
From: Denver, Colorado
If it was me the first thing I would do is get some carb and choke cleaner, although I like the Sea Foam Deep Creep because you can spray it through the TB while the engine is running, and make sure your whole induction system is clean.
First take off your Lid and MAF and make sure that they are both good and clean, if not use some of the cleaner to get them clean.
Second, start the engine and run some of the Deep Creep through your TB making sure there's no oil or dirt on it.
Lastly if that doesn't work I would just go grab a cheap paper filter like a Fram or something and pop that in.
As I said above switching to a K&N filter is what caused the same problem with my car. My theory is that with the increased air, my motor was still getting the same amount of fuel and the stock trim settings couldn't compensate for it, and thus it ran lean.
That's your cheapest route to start off with I think. I'm hesitant to say that it's the fuel pump, but it probably couldn’t hurt to change your fuel filter if it has some miles on it. If it's not the induction some how I would take it to a tuner to see where your AF is set at.
I'm curious to see how things turn out for you.
First take off your Lid and MAF and make sure that they are both good and clean, if not use some of the cleaner to get them clean.
Second, start the engine and run some of the Deep Creep through your TB making sure there's no oil or dirt on it.
Lastly if that doesn't work I would just go grab a cheap paper filter like a Fram or something and pop that in.
As I said above switching to a K&N filter is what caused the same problem with my car. My theory is that with the increased air, my motor was still getting the same amount of fuel and the stock trim settings couldn't compensate for it, and thus it ran lean.
That's your cheapest route to start off with I think. I'm hesitant to say that it's the fuel pump, but it probably couldn’t hurt to change your fuel filter if it has some miles on it. If it's not the induction some how I would take it to a tuner to see where your AF is set at.
I'm curious to see how things turn out for you.
TECH Apprentice
Joined: Apr 2005
Posts: 319
Likes: 1
From: North Carolina
Well I would do what the last person said and then check the fuel filter before you dive into the fuel pump. Fuel pump is easy if you use the trap door method. Pump is a bit pricey though.
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Change the fuel filter yearly just to be safe. you never know.. it takes just one tank of dirty gas (imagine filling up your car just as the tanker truck is unloading fuel and stirring up sediments) and the filter will clog and flow poorly. running 87 octane may just have caused it as well though.
TECH Apprentice
Joined: Oct 2007
Posts: 303
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From: eastern ky
a k&n filter wont cause ur car to lean itself out to the point where ur car throws codes, yes they flow better but not that much better, i have to agree sounds like a fuel pressure problem, possibly a fuel pump or stopped up FUEL filter (not air filter) lol.
Thread Starter
TECH Enthusiast
iTrader: (6)
Joined: Nov 2006
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From: Pineville, LA
I got a fuel filter today and hopefully it will solve the problem. The car doesn't run bad when the light is on but I hate the service engine soon light being illuminated! 
