p0171, p0302
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Joined: Sep 2012
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p0171 code
Trying to figure this one out.
I know 0171 is lean on bank one, and 0302 is a misfire on cylinder 2.
Replaced spark plug and coil pack on cylinder 2.
2002 f150 5.4 240k miles
Engine runs nice and smooth most of the time, but when the code pops up will stumble at an idle, and just feels like it is lacking in power. Put a fuel pressure gauge on it this morning while drinking a cup of coffee while thinking of what to check/change next. Fuel pressure was hovering around 30 psi at idle. with the engine off, I'd bleed the pressure, turn the key and it would read 35.
Trying to decide if I need to focus on cylinder 2 components or common items to bank 1.
I know 0171 is lean on bank one, and 0302 is a misfire on cylinder 2.
Replaced spark plug and coil pack on cylinder 2.
2002 f150 5.4 240k miles
Engine runs nice and smooth most of the time, but when the code pops up will stumble at an idle, and just feels like it is lacking in power. Put a fuel pressure gauge on it this morning while drinking a cup of coffee while thinking of what to check/change next. Fuel pressure was hovering around 30 psi at idle. with the engine off, I'd bleed the pressure, turn the key and it would read 35.
Trying to decide if I need to focus on cylinder 2 components or common items to bank 1.
Last edited by Taper123; Jun 24, 2018 at 11:02 AM. Reason: Only one code now
98 F150 5.4L E40D/4R100
Joined: Nov 2006
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From: MI
Disregard the 171 for now. You don't have coil packs on that engine. The 5fours use coils, 1 per cylinder.
Hard to say since you didn't post replacement parts used. Regardless, start swapping hardware with cylinder 1 until you get the miss to move. If that doesn't shed any light, -compression test.
Hard to say since you didn't post replacement parts used. Regardless, start swapping hardware with cylinder 1 until you get the miss to move. If that doesn't shed any light, -compression test.
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I had the p0171 on my 02 5.4 f-150. Ended up replacing all the rubber vacuum lines on the intake manifold and that cured the lean codes. Most of the original vacuum lines were deteriorated to the point they crumbled and were cracked when I removed them.
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Finally got back to this as I need my truck soon. Driving my car I feel so low to the ground.
Was messing with it, and when I wiggled the fuel injector to cylinder two, it smoothed out. One of the O-rings had a crack in it. Replaced all the seals on that injector and it seems to have corrected my problem. Changed several vacuum connection hoses as well, since they were super dry rotted and cracked. Only one in good shape was the pcv valve one as I had changed it in the last two years.
Will drive it this week to see if this takes care of it.
Was messing with it, and when I wiggled the fuel injector to cylinder two, it smoothed out. One of the O-rings had a crack in it. Replaced all the seals on that injector and it seems to have corrected my problem. Changed several vacuum connection hoses as well, since they were super dry rotted and cracked. Only one in good shape was the pcv valve one as I had changed it in the last two years.
Will drive it this week to see if this takes care of it.
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I bought this truck (2002 f150 5.4) used in 2004 with 14k miles on it. 240k Now. The things I've had to replace:
Radiator : leaked at 230k
Heater core : leaked at 200k
Intake Manifold : crossover tube leaked at 210k
Changed all coil on plugs with motorcraft parts at 185k
pcv valve and hose assembly at 180k
The usual brakes and routine things...
Have always used motorcraft 5-20 oil as well.
So if it starts stuttering again... hat gives an idea of the age of some components
Radiator : leaked at 230k
Heater core : leaked at 200k
Intake Manifold : crossover tube leaked at 210k
Changed all coil on plugs with motorcraft parts at 185k
pcv valve and hose assembly at 180k
The usual brakes and routine things...
Have always used motorcraft 5-20 oil as well.
So if it starts stuttering again... hat gives an idea of the age of some components
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Ok still had a bit of a rough idle when stopped or going really slow.
Long term fuel trim for bank one is reading high at 28.9
Noticed bank one oxygen sensor 2 only changes voltage at start up and never peaks as high as bank 2, stays 0v after that. Bank 2 does the same initial cycle then seems to level out at .7v
Both banks on sensor one bounce up and down as they should.
Or at least that's my interpretation from the torque app I use.
Any advice or what I should set the app to monitor?
Long term fuel trim for bank one is reading high at 28.9
Noticed bank one oxygen sensor 2 only changes voltage at start up and never peaks as high as bank 2, stays 0v after that. Bank 2 does the same initial cycle then seems to level out at .7v
Both banks on sensor one bounce up and down as they should.
Or at least that's my interpretation from the torque app I use.
Any advice or what I should set the app to monitor?
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Joined: Sep 2012
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Changed the downstream o2 sensor on bank one. Now it gets voltage readings. Truck still idles a bit rough and stumbles at low rpms. Long term fuel trim for bank one still higher than bank 2. Pending 0171 shows up.
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Thread Starter
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Joined: Sep 2012
Posts: 78
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Disregard the 171 for now. You don't have coil packs on that engine. The 5fours use coils, 1 per cylinder.
Hard to say since you didn't post replacement parts used. Regardless, start swapping hardware with cylinder 1 until you get the miss to move. If that doesn't shed any light, -compression test.
Hard to say since you didn't post replacement parts used. Regardless, start swapping hardware with cylinder 1 until you get the miss to move. If that doesn't shed any light, -compression test.
