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2009 F-150 5.4 3v P0345 and P0349

 
Old 02-09-2019, 10:42 AM
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Originally Posted by techrep View Post
02 sensor bank one .. post cat. could pull it and clean it up and reinstall.. give that a shot.
Thank you very much for the quick responses! I very much appreciate it! I see the post cat O2 sensors are fairly cheap, so I値l order some Monday and I値l replace them. I guess it痴 okay to run with it running lean?
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Old 02-09-2019, 11:15 AM
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Old 02-09-2019, 11:48 AM
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Originally Posted by techrep View Post
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This.
My '11 threw a different post cat code shortly after buying it. From what I read, the post cat O2 sensors are read primarily upon decel. Mine cleared by itself only to reappear.
Drive a few start/stop cycles to see if the CEL clears. This will help in diagnosing the cause.

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Old 02-12-2019, 09:35 AM
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Well I decided to throw a fuel pressure gauge on it yesterday. KOEO was about 50psi then slowly bled off. KOER was 20-22psi. When I would slowly increase the RPMs it would drop back to 20psi, if I punched the gas hard it would jump to 50psi then bleed back down. I知 thinking FPDM. I had my local Napa order one which will be here today. Any thoughts from you guys?
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Old 02-12-2019, 09:42 AM
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Originally Posted by jaredmiller01 View Post
Well I decided to throw a fuel pressure gauge on it yesterday. KOEO was about 50psi then slowly bled off. KOER was 20-22psi. When I would slowly increase the RPMs it would drop back to 20psi, if I punched the gas hard it would jump to 50psi then bleed back down. I知 thinking FPDM. I had my local Napa order one which will be here today. Any thoughts from you guys?
FPDM either work or not.. Fuel pressure sensor would be a good choice if you want to toss parts at it.
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Old 02-12-2019, 10:09 AM
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Okay thanks! Where is the pressure sensor located?
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Old 02-12-2019, 10:13 AM
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Originally Posted by jaredmiller01 View Post
Okay thanks! Where is the pressure sensor located?
On the drivers side fuel rail.
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Old 02-12-2019, 06:02 PM
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Well the new FPDM was a Dorman and actually put out less pressure than the original one so I put the original one back in it and I知 gonna take the new one back LOL. I wish I could get to the bottom of the hesitation issue. I知 gonna clean the MAF tomorrow even though I致e replaced it about a month ago. I also need to clean the TB. I知 starting to think it痴 torque converter. But if it痴 that I知 just gonna run it until that goes. I知 just trying to keep this one going until after graduation so I can move to an Ecoboost😎
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Old 02-12-2019, 07:03 PM
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The fuel pressure should be around 35 PSI at idle and not change too much under load. The higher initial reading at KOEO is the fuel pump priming the fuel rail prior to engine start.
A restriction in the system, a weak pump (low power supply or defect), or even a fuel tank venting problem ( slow drop in FP) are possibilities.
The PCM will try to cover up low fuel pressure by extending injector pulse width, but that'll only go so far.

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Old 02-13-2019, 08:39 AM
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That cleared some things up for me, thank you! Maybe my pump is getting a little weak. I mean that could cause some hesitation I would think? I guess Ill just keep running it until it gets worse and then replace the pump. Thanks!
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