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  #1  
Old 12-09-2013, 11:26 PM
Crich98ford Crich98ford is offline
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Default 4.0l running lean bank 1 and 2

I have a 98 4.0l with 121,432 miles on it and my CEL comes on about every 300 miles and reads p0171 and p0174. So I changed my fuel filter twice. I have checked my fuel pump (65-67 psi) I have cleaned my MAF sensor my IAT sensor and my IAC sensor. And my upstream and down stream O2 sensors and the codes still come up and now my MPG has dropped also I have checked for vacuum leaks and I don't see any if anyone could help me out that would be great
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Old 12-10-2013, 09:02 AM
Crich98ford Crich98ford is offline
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Default Re: 4.0l running lean bank 1 and 2

I tested the maf sensor by starting my truck and unplugging it and it didn't stumble until I pluged the sensor back in. And I don't know what that means
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Old 12-10-2013, 09:14 AM
RangerSchool RangerSchool is offline
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Originally Posted by Crich98ford View Post
I tested the maf sensor by starting my truck and unplugging it and it didn't stumble until I pluged the sensor back in. And I don't know what that means
The truck should not run properly with the maf disconnected, it should eventually stall. My guess is either a bad MAF or a leaking intake manifold. I would do the MAF FIRST. $60 and 10 minutes labor. Also Make sure the air intake is not cracked!
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Last edited by RangerSchool; 12-10-2013 at 09:31 AM.
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Old 12-10-2013, 09:43 AM
Springtown FX4 Springtown FX4 is offline
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Default Re: 4.0l running lean bank 1 and 2

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Originally Posted by RangerSchool View Post
The truck should not run properly with the maf disconnected, it should eventually stall. My guess is either a bad MAF or a leaking intake manifold. I would do the MAF FIRST. $60 and 10 minutes labor. Also Make sure the air intake is not cracked!
The truck will run properly without the MAF sensor connected it creates open loop or something. So often times if the maf is connected and its running bad and unhooking it creates better running conditions this can sometimes indicate a bad or misreading MAF sensor. Start by cleaning it properly. Also it seems your chasing the fuel side of the problem instead of the air side, which sounds like your issue you either have air leak or misreading sensor more than likely due to lean condition codes. Once again check for air leaks around pcv, all pcv hoses leading into engine, around intake, throttle body, etc.
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Last edited by Springtown FX4; 12-10-2013 at 09:55 AM.
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Old 12-10-2013, 09:55 AM
RangerSchool RangerSchool is offline
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Originally Posted by Springtown FX4 View Post

The truck will run properly without the MAF sensor connected it creates open loop or something. So often times if the maf is connected and its running bad and unhooking it creates better running conditions this can sometimes indicate a bad or misreading MAF sensor. Start by cleaning it properly.
I respectfully disagree. Go try it on your truck. If you disconnect the maf from a properly running system the car should run worse. If nothing happens or it runs better that is a good indication the maf is bad.

The MAF IS USED ALL THE TIME. THE O2's are what changes in open/closed loop.

He cleaned the MAF!
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Last edited by RangerSchool; 12-10-2013 at 10:04 AM.
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Old 12-10-2013, 10:21 AM
Crich98ford Crich98ford is offline
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Default Re: 4.0l running lean bank 1 and 2

I have cleaned the maf with crc cleaner twice. But I don't understand why my truck would stumble when I plug the maf sensor back in

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I'm chasing the fuel side because I tried useing acetone as an additive and now it's throwing codes
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Old 12-10-2013, 10:42 AM
Springtown FX4 Springtown FX4 is offline
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Default Re: 4.0l running lean bank 1 and 2

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Originally Posted by RangerSchool View Post
I respectfully disagree. Go try it on your truck. If you disconnect the maf from a properly running system the car should run worse. If nothing happens or it runs better that is a good indication the maf is bad.

The MAF IS USED ALL THE TIME. THE O2's are what changes in open/closed loop.

He cleaned the MAF!
I will admit i didnt not see that he already did clean the MAF(my bad). I have on mulitple occasions turned my truck on and disconnected the MAF sensor and guess what it runs fine. so i will disagree, and i did state that if he disconnects the MAF sensor and it gets better then he more than likely has a bad MAF.

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Quote:
Originally Posted by Crich98ford View Post
I have cleaned the maf with crc cleaner twice. But I don't understand why my truck would stumble when I plug the maf sensor back in

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I'm chasing the fuel side because I tried useing acetone as an additive and now it's throwing codes
Well stating that before would have justified why you were chasing fuel on multiple occations...leaving stuff out like that doesnt help us diag. over the internet...that just makes it much harder to do so. it stumbles because its not working properly there is a good chance its bad.
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  #8  
Old 12-10-2013, 10:42 AM
RangerSchool RangerSchool is offline
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Default Re: 4.0l running lean bank 1 and 2

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Originally Posted by Crich98ford View Post
I have cleaned the maf with crc cleaner twice. But I don't understand why my truck would stumble when I plug the maf sensor back in

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I'm chasing the fuel side because I tried useing acetone as an additive and now it's throwing codes
I don't have an answer for you about why the maf acts that way.....other then to say my best guess is your MAF is fubared.......for $60 I would buy a new one....

why are you chasing the fuel?........your pressure was fine.......and I would never put acetone in my tank................what codes?
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Old 12-10-2013, 10:46 AM
Crich98ford Crich98ford is offline
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Default Re: 4.0l running lean bank 1 and 2

My dad is thinking that I might need to replace the injectors or just the o rings on the injectors
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Old 12-10-2013, 10:46 AM
RangerSchool RangerSchool is offline
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Default Re: 4.0l running lean bank 1 and 2

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Originally Posted by Springtown FX4 View Post
I will admit i didnt not see that he already did clean the MAF(my bad). I have on mulitple occasions turned my truck on and disconnected the MAF sensor and guess what it runs fine. so i will disagree, and i did state that if he disconnects the MAF sensor and it gets better then he more than likely has a bad MAF.

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Well stating that before would have justified why you were chasing fuel on multiple occations...leaving stuff out like that doesnt help us diag. over the internet...that just makes it much harder to do so. it stumbles because its not working properly there is a good chance its bad.
I don't know why he is chasing fuel.........his pressure is perfec!......
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  #11  
Old 12-10-2013, 10:47 AM
ranger024x4 ranger024x4 is offline
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Default Re: 4.0l running lean bank 1 and 2

Personally, it sounds like either a vac. leak or intake mani leak. Not sure if the OHV's are like the SOHC's. but there is a 90* vac line right under the throttle body that always fails. Could be your issue.
Quote:
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I respectfully disagree. Go try it on your truck. If you disconnect the maf from a properly running system the car should run worse. If nothing happens or it runs better that is a good indication the maf is bad.
not necessarily. Unplugging it puts the ECU into a 'base' setting.


My escort ran like crap with the maf plugged in. I unplugged it and it would clear up. After replacing the maf it ran 100% better.
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  #12  
Old 12-10-2013, 10:54 AM
RangerSchool RangerSchool is offline
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Default Re: 4.0l running lean bank 1 and 2

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Originally Posted by ranger024x4 View Post
Personally, it sounds like either a vac. leak or intake mani leak. Not sure if the OHV's are like the SOHC's. but there is a 90* vac line right under the throttle body that always fails. Could be your issue.


not necessarily. Unplugging it puts the ECU into a 'base' setting.


My escort ran like crap with the maf plugged in. I unplugged it and it would clear up. After replacing the maf it ran 100% better.
definitely could be a vacuum issue.....but he did say he checked for those.....so I can only go by the feedback.......I think the manifold bolts can loosen up on the ohv........he could put a torque wrench on them and see what he has.........I am not a parts thrower but with the info he gave and the cost/ labor for a maf I think it is worth the gamble..........
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  #13  
Old 12-10-2013, 10:58 AM
ranger024x4 ranger024x4 is offline
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Default Re: 4.0l running lean bank 1 and 2

Quote:
Originally Posted by RangerSchool View Post
definitely could be a vacuum issue.....but he did say he checked for those.....so I can only go by the feedback.......I think the manifold bolts can loosen up on the ohv........he could put a torque wrench on them and see what he has.........I am not a parts thrower but with the info he gave and the cost/ labor for a maf I think it is worth the gamble..........
definitely could be.

Something that causes a lean condition on both sides would lead me to believe its something that could affect that.. like maf, vac leak, or fuel pressure (doubtful fuel issue though).

How is your air filter?
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  #14  
Old 12-10-2013, 11:09 AM
cowboybilly9mile cowboybilly9mile is offline
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Default Re: 4.0l running lean bank 1 and 2

Quote:
Originally Posted by Crich98ford View Post
I have a 98 4.0l with 121,432 miles on it and my CEL comes on about every 300 miles and reads p0171 and p0174. So I changed my fuel filter twice. I have checked my fuel pump (65-67 psi) I have cleaned my MAF sensor my IAT sensor and my IAC sensor. And my upstream and down stream O2 sensors and the codes still come up and now my MPG has dropped also I have checked for vacuum leaks and I don't see any if anyone could help me out that would be great
Quote:
Originally Posted by Crich98ford View Post
My dad is thinking that I might need to replace the injectors or just the o rings on the injectors
The 90's 4.0's have a real good track record of leaky intake gaskets (vacuum leaks); as the condition progresses it's not uncommon for the engine to consume a small but steady amount of coolant. So, knowing this you really owe it to yourself to retorque the lower intake; IF this is the issue and IF you catch it soon enough, you can usually avoid having to replace the gasket. The retorque should take ~20 minutes in your personal or a friends garage, time is long because one or two of the fasteners are sucky to torque down (access, one in back in particular, have a swivel handy IIRC), and the cost for you to do this is $0. Personally, I've retorqued lower intakes on probably 12 90's 4.0's including the one I had; almost all of them had at least one intake bolt that was just finger tight.

Stop pulling wires leading to sensors and douching/cleaning the MAF and then speculating, lol, MAF is clean and presumably for now, not damaged in the process, focus on diagnosing a lean condition which is most commonly a vac leak on these engines, once that is ruled out pursue other diagnostics for running lean.
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Last edited by cowboybilly9mile; 12-10-2013 at 11:13 AM.
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  #15  
Old 12-10-2013, 01:06 PM
Crich98ford Crich98ford is offline
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Default Re: 4.0l running lean bank 1 and 2

I'll try and retorque it

----------

Cowboybilly9mile what is the best way to retorque it I'm learning how to do this stuff
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