still getting p0171 code
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still getting p0171 code
1999 F250 5.4 95,000 miles
Here is what I have done:
Cleaned MAF sensor
checked for vacuum leaks using Carb cleaner found leak in the pvc hose so I replaced this. Cannot locate any other leaks. Although my truck is running better I am still getting the p0171 code. Not sure where to start next.
Here is what I have done:
Cleaned MAF sensor
checked for vacuum leaks using Carb cleaner found leak in the pvc hose so I replaced this. Cannot locate any other leaks. Although my truck is running better I am still getting the p0171 code. Not sure where to start next.
Lead Driver
Joined: Sep 2006
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Lets take a look at the code.
171 is bank 1 "system" too lean.
This means the fuel table has reached it's 'rich' limit.
Some reasons that can be the cause.
a. fuel pressure to high/faulty.
b. regulator leaking thru the hose into the intake.
c. low fuel pressure.
d. vapor recovery system.
e. induction air leaks.
f. oil dip stick allowing air into the crank case.
g. EGR system, vacuum side or exhaust side.
h. leaking fuel injector.
i. exhaust leak allowing air into the stream, the OX sensor detects.
You need to go down this list until one or more problems are found and corrected.
171 is bank 1 "system" too lean.
This means the fuel table has reached it's 'rich' limit.
Some reasons that can be the cause.
a. fuel pressure to high/faulty.
b. regulator leaking thru the hose into the intake.
c. low fuel pressure.
d. vapor recovery system.
e. induction air leaks.
f. oil dip stick allowing air into the crank case.
g. EGR system, vacuum side or exhaust side.
h. leaking fuel injector.
i. exhaust leak allowing air into the stream, the OX sensor detects.
You need to go down this list until one or more problems are found and corrected.
Posting Guru
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From: Back where I started...
A lean code means that there is an excessive amount of oxygen (or a lack of fuel) on one or both banks of the engine (being burned). Say you have a vacuum leak, i.e. a bad intake gasket. That means the motor is getting unmetered air (air that is not being measured by the maf) into the combustion chamber. If the leak is bad enough that it cannot be compensated for by the pcm by adding fuel, it's going to set the code. Could be any one of the things Bluegrass listed above, could be a bad o2 sensor, could even be a misfire (unburned oxygen makes it's way to the o2 sensor, which sees the excess air)
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gafft1, I have a 97 F150 w/5.4 194,000 miles and I'm getting the same code P/O 171
I tried the same things you did to find the problem I also Regasketed the throttle body
to see if that was sucking air . I checked out things that Bluegrass7 listed. But I'm afraid that the intake to the motor may have to come off . I was hopeing that the fuel pressure reg. was the problem . Let me know what you come up with ???
I tried the same things you did to find the problem I also Regasketed the throttle body
to see if that was sucking air . I checked out things that Bluegrass7 listed. But I'm afraid that the intake to the motor may have to come off . I was hopeing that the fuel pressure reg. was the problem . Let me know what you come up with ???
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I unhooked the cord off of the DPFE sensor and there was no change to the way my truck was acting does this mean that the sensor is bad? Is there a way to test this and the MAF sensor to see if they need replaced? I hate to start replacing parts if there is nothing wrong with them.
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From: St Louis
You don't have either a leaky injector,a faulty DPFE sensor, or a MAF problem.
I'd focus on intake air leaks.
Connect your scan tool and collect live data. Specifically, monitor the long and short term fuel trims. Look for long terms limits skewed near the limit. Then, while monitoring the short term trims, repeat the spray tests with carb or brake cleaner or an unlit propane torch. The instant that the flammable hits an intake leak, the short term trim will spike and then slowly return back to its previous level.
Since you're only getting a fault code on one side, you will likely find that the actual problem is limited to that side only.
Steve
I'd focus on intake air leaks.
Connect your scan tool and collect live data. Specifically, monitor the long and short term fuel trims. Look for long terms limits skewed near the limit. Then, while monitoring the short term trims, repeat the spray tests with carb or brake cleaner or an unlit propane torch. The instant that the flammable hits an intake leak, the short term trim will spike and then slowly return back to its previous level.
Since you're only getting a fault code on one side, you will likely find that the actual problem is limited to that side only.
Steve
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From: Broken Arrow, OK
Originally Posted by projectSHO89
Connect your scan tool and collect live data.
Like he said, you don't have a problem with anything that would affect both banks and you don't have a problem with something adding fuel. If it was an adding fuel problem you would have a code 172. You more than likely have an airleak somewhere and the chances of finding it with carb cleaner are slim if it is in a place that is hard to access. A smoke machine will usually find most vacuum leaks and a shop should charge you about $30 to check it for you. For the same $30 you could probably buy a small party smoke machine and rig something up to connect it too your truck.
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I searched all of the vacuum lines (I think) and still cannot find a leak. I did notice that the exhaust manifold is rusted and leaking. Would this cause the P0171 code? How hard is the exhaust manifold to replace? are there any special tools required or should i take to the shop to have it done. If so approximately how much would that cost me.
Lead Driver
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Have you cleared the code?
You may have fixed the problem but looking at old code set, yet.
A really open break in the exhaust can admit air and cause the Ox sensor to detect it and richen the tables to the limit, setting the same code for that bank, if it is the same side.
If it it rusted that bad chances are the nuts will break the studs off.
Let a dealer do the job.
You may have fixed the problem but looking at old code set, yet.
A really open break in the exhaust can admit air and cause the Ox sensor to detect it and richen the tables to the limit, setting the same code for that bank, if it is the same side.
If it it rusted that bad chances are the nuts will break the studs off.
Let a dealer do the job.
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Yeah I cleared the codes. I found two quarter size rust holes in the top of the exhaust manifold. Will it cause any damage to the truck if I drive it as it is. Or should I get the problem fixed right away. The bolts look pretty rusty as well so it don't look like this is going to be a job for me. Does anyone know approximately how much this is going to cost.
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