03 5.4 running rich and now lean
#1
03 5.4 running rich and now lean
Hello
My 03 with a 5.4 has been hesitating a when you accelerate and cutting out as well as idling rough and die when you slow down. It does all this intermittently. Not every stop or every time you accelerate. I first got a code for the MAF and both banks running rich (PO102, PO172, PO175) so I cleaned the throttle body and MAF. The running rich code came back (PO172, PO175) so I then changed the MAF and air filter . It seemed to help for a day or so then my light came on and I figured the same code was back but to my surprise it was now both banks running lean(PO171, PO174) so I took my MAF back and got another one. It hasn't set a code yet but it is still running poorly. I am looking for ideas.
I have changed all the COP's and plugs as well
Thanks
My 03 with a 5.4 has been hesitating a when you accelerate and cutting out as well as idling rough and die when you slow down. It does all this intermittently. Not every stop or every time you accelerate. I first got a code for the MAF and both banks running rich (PO102, PO172, PO175) so I cleaned the throttle body and MAF. The running rich code came back (PO172, PO175) so I then changed the MAF and air filter . It seemed to help for a day or so then my light came on and I figured the same code was back but to my surprise it was now both banks running lean(PO171, PO174) so I took my MAF back and got another one. It hasn't set a code yet but it is still running poorly. I am looking for ideas.
I have changed all the COP's and plugs as well
Thanks
#3
The mistake is not interpreting the codes correctly.
You went into guessing and guessed wrong.
I'm not trying to rub you but to get you to see what the correct way is.
You cannot just go by the first words you see and think it suggests what parts are the cause unless you have previous experience with those codes..
The rich/ lean is the fuel tables shifted out of limits that sets the codes.
.
You have an air leak in the intake system.
.
The OX sensors detects the extra air and tries the 'Richen' up the fuel to compensate but cannot accomplish.
This causes rough idle and stalling.
This is where part of the code description comes from.
Has nothing to do with the Mass Air meter or the throttle body per sey.
Good luck.
.
You went into guessing and guessed wrong.
I'm not trying to rub you but to get you to see what the correct way is.
You cannot just go by the first words you see and think it suggests what parts are the cause unless you have previous experience with those codes..
The rich/ lean is the fuel tables shifted out of limits that sets the codes.
.
You have an air leak in the intake system.
.
The OX sensors detects the extra air and tries the 'Richen' up the fuel to compensate but cannot accomplish.
This causes rough idle and stalling.
This is where part of the code description comes from.
Has nothing to do with the Mass Air meter or the throttle body per sey.
Good luck.
.
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#12
I took it to the shop they are not sure what is wrong with it yet they unplugged my MAF sensor and said to drive it and see if it messed up. It didn't mess up so I plugged it back in and ran great had good fuel trims and the MAF was reading good. After about 40 miles the MAF readings would be erratic and go to 0.0 then jump all around and the short term fuel trims would run real rich and jump as well. When it did that it started cutting out so I unplugged it and it ran good again. So I plugged it back in it ran good again for about 35-40 miles again and then the MAF readings messed up again. My question is it my MAF or is it something in my computer? I have replaced the MAF but could I have got a Bad part from the auto supply ?
Thanks
Thanks
#13
You said you checked for leaks in and around the intake, but you didn't mention how. When I suspect a vacuum leak or an intake leak, I'll use carb cleaner or ether, and spray around sealing areas on the intake components. While doing this, listen for engine rpm to change suddenly, there's your leak. Also, have you made any recent mods to truck at all, anywhere?
#14
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