MIL when pulling boat
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Senior User
Joined: Jun 2005
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MIL when pulling boat
Hello,
I have a "98" Expedition with a 5.4 engine. Lately when I pull my boat and accelerate, the valves rattle and then the check engine light comes on. Codes are PO171 and PO174, bank 1 lean, bank 2 lean. It has done this three times. I cleaned the MAF sensor after the second time. Any ideas?
I have a "98" Expedition with a 5.4 engine. Lately when I pull my boat and accelerate, the valves rattle and then the check engine light comes on. Codes are PO171 and PO174, bank 1 lean, bank 2 lean. It has done this three times. I cleaned the MAF sensor after the second time. Any ideas?
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Posting Guru
Joined: Apr 2005
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From: duncan oklahoma
check the fuel filter for restriction.clean the sensor and disconnect the batteryfor 10 min. reconnect and try driving the crap out of it at wide open throttle a few times.this will reset the barometric pressure in the computer.
Mountain Pass
Joined: Aug 2004
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my mechanic went through a whole slew of possible fixes for this including cleaning the MAF sensor, changing PCV valve, checking for vacuum leaks, cleaning injectors, etc. nothing would fix it. Eventually he found some info that MAF sensors can go bad and still test good. He replaced the MAF sensor and the problem went away.
Good luck!
Good luck!
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Joined: Dec 2001
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From: Louisville,Ky.
Yep, I would clean the MAF And check the PCV hose assembly, especially behind the intake in the elbow for cracks.
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Joined: May 2005
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98 5.4L Expy codes 171 and 174
First want to say I really enjoy the group. About a year ago I added a cat-back exhaust system and high flow air intake to my 98 expedition (5.4L, 4WD) w/ 86,000 miles. About 6 months ago, right after I replaced the stock tires (26570R17s) w/BFG 28570R17s, I started getting a recurring CEL with associated 171 and 174 codes on both banks. Since that time, I replaced the fuel filter (and run lucas fuel injector cleaner), also replaced the EGR, EGR solenoid, cracked vacuum lines/boots, PVC valve....always resetting the engine light at autozone or by disconnecting the battery. Additionally, I have tried cleaning the MAF several times. Despite some of these fixes resulting in some noticable improvements in how my expy runs, when I'm driving at highway speed (75mph) I still hear pinging when climbing up hills, and normaly get the CEL after 1 or 2 days of driving.
Any Ideas on what to do next?
Any Ideas on what to do next?
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EGR flow problems will make it ping in the midrange low-to-moderate acceleration.
I would check the piping for the EGR for carbon buildup, and make sure the EGR works (put a hose on it, suck on it, and the idle should get really crappy, if not stall).
I've heard of carbon buildup in the EGR piping, without a code logged, enough to cause it to ping.
I would check the piping for the EGR for carbon buildup, and make sure the EGR works (put a hose on it, suck on it, and the idle should get really crappy, if not stall).
I've heard of carbon buildup in the EGR piping, without a code logged, enough to cause it to ping.
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Joined: May 2005
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Since I've replace about everything but the MAF sensor, is there an easy way to check if the MAF is morking or not prior to spending additional $$. Also, is there a recommended aftermarket MAF sensor, or is the motorcraft unit best? in the event mine does not test OK.
Post Fiend
Joined: Jun 2005
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From: North west La
I was throwing those codes a lot till I replaced all my vacuum lines. My last line was hard plastic one on the firewall going to the ac. It was split on the bottem & it took a mirror & some hunting o find it. It didn't show by spraying carb cleaner on it. I think its fixed now. I'm still throwing a code for the evap system that no mechanic can fix. Its had 3 smoke test no leaks but it still throws the code for a small leak in the evap system PO442.
Last edited by lariat97; Jul 18, 2005 at 07:12 PM.
Mountain Pass
Joined: Aug 2004
Posts: 111
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goldar, I don't want to make you spend $$ unneccesarily, all I can tell you is that my mechanic whom I've used for 10 years and trust very much tried everything to find the problem (checked for vacuum leaks, PCV valve, Cleaned Injectors, Clean MAF, Test MAF, etc) and nothing would fix the problem. Even though the MAF tested good, it was contaminated enough to throw off the barometric pressure readings (going from memory of the conversation I had with my mechanic) and replacing it fixed the problem. Hope this helps.