Strange OBD Codes
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Strange OBD Codes
I have a 97 F150 with the 5.4 Triton. I don't have any additions, it is entirely stock (at this point). My check engine light came on, it turned out to be driver's upstream 02 sensor. Replaced it, plugged in my AutoXray, reset the computer and was off. It came back on about 50 miles later. The code said passenger upstream 02. Replaced, reset, and go. Check engine came back on and now, get this, I get 4 codes:
P171 (Bank 1 too lean)
P172 (Bank 1 too rich)
P174 (Bank 2 too lean)
P175 (Bank 2 too rich)
A friend knew someone at Ford, called them about this and they told me to replace all 4 02 sensors, which I did (the passenger upstream was a total nightmare!). So, with all 4 new 02 sensors, I reset, and about 20 miles later my check engine light comes on again, and the same 4 codes are being stored.
Does anyone have ANY idea what to do? I want to simply rechip my truck with a Diablo or something but need to figure this out first. I posted something a while back on this and it seemed like someone mentioned something about an MAF (mass air flow) sensor. Can someone point me in the right direction? Where is, or are, these MAF sensors? Is there any other suggestions?
Any help is greatly appreciated!
Dwayne
P171 (Bank 1 too lean)
P172 (Bank 1 too rich)
P174 (Bank 2 too lean)
P175 (Bank 2 too rich)
A friend knew someone at Ford, called them about this and they told me to replace all 4 02 sensors, which I did (the passenger upstream was a total nightmare!). So, with all 4 new 02 sensors, I reset, and about 20 miles later my check engine light comes on again, and the same 4 codes are being stored.
Does anyone have ANY idea what to do? I want to simply rechip my truck with a Diablo or something but need to figure this out first. I posted something a while back on this and it seemed like someone mentioned something about an MAF (mass air flow) sensor. Can someone point me in the right direction? Where is, or are, these MAF sensors? Is there any other suggestions?
Any help is greatly appreciated!
Dwayne
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you're MAF is located in you air box.. open up were you're air filter is and look inside you can't miss it.. the wire are located just underneath... pull back the boot but don't try to rip it out or you'll have bigger problems... spray some cleaner and see if that will help...
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well with all new o2 sensors and you clean up the MAF you might want to try cleaning you're throttle body, EGR ports. if you're EGR is leaking or clogged up it will cause some lean,rich problems, but i'm not to sure about pulling codes on both banks like that...process of elimination...
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My book only shows a picture of an EGR vacuum regulator. Is that the actual valve? It mentions that a vacuum line is attached, but does not really locate it on the engine. Also, when you say to clean the ports, I would also assume you mean the ports where the vacuum line(s) attach?
Thanks for all the newbie help.
Dwayne
Thanks for all the newbie help.
Dwayne
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4 codes, 2 banks...interesting. I would check the vacuum lines and all elbows from the pcv to the intake. My understanding is that a lot of 5.4's have leaks from these elbows deteriorating. You might check out this thread to see if it provides any more insight.
https://www.ford-trucks.com/forums/s...ght=rough+idle
https://www.ford-trucks.com/forums/s...ght=rough+idle
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You have to remove the throttlebody to get to the EGR ports in the intake manifold.
The PCV hose usually tends to crack back behind the throttlebody where it attatches to the intake manifold.
You can see the MAF thru the removable side of the air filter box looking in the end the is going towards the engine.
The PCV hose usually tends to crack back behind the throttlebody where it attatches to the intake manifold.
You can see the MAF thru the removable side of the air filter box looking in the end the is going towards the engine.
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Ok guys, I had a work trip I had to go to so it delayed this whole thing... but, I got back, took the MAF off, cleaned it up with carb cleaner (it was dirty) and put it back on, reset the comp and gave it a test drive. The check engine came back on...sigh. I bought a new MAF ($110), put it on, reset the comp, and guess what? The check engine is back on. I reset it, just to see if it would stay cleared, but it came back on. The code I am getting now is:
102: Mass or Volume Air Flow Circuit Low Input
It also shifted really, really hard both times I reset it. Does anyone have any clues here? I'm going to check my fuses but I have a feeling there is something else wrong. Also, does the computer keep some record of how the engine has been performing that may be causing the computer to misbehave?
This is getting frustrating, any help is greatly appreciated.
Thanks!
102: Mass or Volume Air Flow Circuit Low Input
It also shifted really, really hard both times I reset it. Does anyone have any clues here? I'm going to check my fuses but I have a feeling there is something else wrong. Also, does the computer keep some record of how the engine has been performing that may be causing the computer to misbehave?
This is getting frustrating, any help is greatly appreciated.
Thanks!
