trouble codes...help..
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trouble codes...help..
i have a 99 f150 4.6L and my mpg has sucked for the last month and a half...my cel finally came on today and gave the codes P0172 System too rich (bank 1) and P0175 system too rich (bank 2). what could the problem be..i do have an air intake system on..any ideas? thanks.
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From: Riverside CA.
Endless list
The list could be endless!
But to start, did you just add the intake? I seriously doubt it has anything to do with it though. what have you done or had done to the vehicle recently (day or 2 before the CE light)?
Since it is on both banks look for something that is common to the engine. For example: MAF,Temp sensors, etc... You need to have the sensors monitored to find the part that is causing the problem.
But to start, did you just add the intake? I seriously doubt it has anything to do with it though. what have you done or had done to the vehicle recently (day or 2 before the CE light)?
Since it is on both banks look for something that is common to the engine. For example: MAF,Temp sensors, etc... You need to have the sensors monitored to find the part that is causing the problem.
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i have not done anything to the truck...i have notice a huge decline in mpg for a while and the light has just now come on..i did have an exhaust manifold leak..where all do you check to check for vacuum leaks?
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From: Riverside CA.
Vacuum hoses, the connection to hoses, anywhere there is a gasket.
You can use water or flamable liquid (Carb cleaner/starterfluid, but if you are not experienced don't burn down your truck) be careful.
you can also pinch suspect hoses to close the leak for confirmation.
Is the MAF an aftermarket?
Other than the MPG have you noticed any performance problems at idle, off-throttle, WOT?
You can use water or flamable liquid (Carb cleaner/starterfluid, but if you are not experienced don't burn down your truck) be careful.
you can also pinch suspect hoses to close the leak for confirmation.
Is the MAF an aftermarket?
Other than the MPG have you noticed any performance problems at idle, off-throttle, WOT?
Posting Guru
Joined: Oct 2005
Posts: 2,209
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From: Louisville, Kentucky
The list of causes from the Ford Service manual for lean and rich DTCs: 
- Fuel system
- Excessive fuel pressure
- Leaking/contaminated fuel injectors
- Leaking fuel pressure regulator
- Low fuel pressure or running out of fuel
- Vapor recovery system
- Air leaks after the MAF
- Vacuum Leaks
- PCV system
- Improperly seated engine oil dipstick
- Leaking gasket
- Stuck EGR valve,
- Leaking diaphragm or EVR
- Oil overfill
- Cam timing
- Cylinder compression
- Exhaust leaks before or near the HO2Ss.
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Originally Posted by Aaron Morant
Vacuum hoses, the connection to hoses, anywhere there is a gasket.
You can use water or flamable liquid (Carb cleaner/starterfluid, but if you are not experienced don't burn down your truck) be careful.
you can also pinch suspect hoses to close the leak for confirmation.
Is the MAF an aftermarket?
Other than the MPG have you noticed any performance problems at idle, off-throttle, WOT?
You can use water or flamable liquid (Carb cleaner/starterfluid, but if you are not experienced don't burn down your truck) be careful.
you can also pinch suspect hoses to close the leak for confirmation.
Is the MAF an aftermarket?
Other than the MPG have you noticed any performance problems at idle, off-throttle, WOT?
the rpm's have dropped at times while stopped in gear or moving at idling speed..and a rough idle....and that is it other than the mpg..
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Originally Posted by cneagle87
the rpm's have dropped at times while stopped in gear or moving at idling speed..and a rough idle....and that is it other than the mpg..
it also will hesitate when hitting wot...then it will kick in, power wise....but still not like it should though.
Lead Driver
Joined: Sep 2006
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You have excess (unaccounted for air) entering after the mass air meter.
By definition, the codes are telling that the engine's fuel has shifted too 'rich' hence the drop in fuel mileage. The OX sensors do this in reaction to the fault.
Do not confuse this with the code discription saying 'lean'.
The lean is the computer tables are set to their lean side in an attempt to correct an "engine" rich condition. There is only so far the tables can be shifted and lights the CEL lamp to that effect.
Look for bad hoses, anything that will let air into the intake system where it should not..
By definition, the codes are telling that the engine's fuel has shifted too 'rich' hence the drop in fuel mileage. The OX sensors do this in reaction to the fault.
Do not confuse this with the code discription saying 'lean'.
The lean is the computer tables are set to their lean side in an attempt to correct an "engine" rich condition. There is only so far the tables can be shifted and lights the CEL lamp to that effect.
Look for bad hoses, anything that will let air into the intake system where it should not..
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Originally Posted by firebug8109
One real quick question? How many miles do you have on the truck? When was the last time the truck was tuned up? Plugs, fuel filter, all of that? Has the O2's ever been changed?
i have 131,000 miles on it...the last tune up was about 2 years ago. changed the fuel filter a little over a year ago....o2 sensors are factory.
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Originally Posted by Bluegrass 7
You have excess (unaccounted for air) entering after the mass air meter.
By definition, the codes are telling that the engine's fuel has shifted too 'rich' hence the drop in fuel mileage. The OX sensors do this in reaction to the fault.
Do not confuse this with the code discription saying 'lean'.
The lean is the computer tables are set to their lean side in an attempt to correct an "engine" rich condition. There is only so far the tables can be shifted and lights the CEL lamp to that effect.
Look for bad hoses, anything that will let air into the intake system where it should not..
By definition, the codes are telling that the engine's fuel has shifted too 'rich' hence the drop in fuel mileage. The OX sensors do this in reaction to the fault.
Do not confuse this with the code discription saying 'lean'.
The lean is the computer tables are set to their lean side in an attempt to correct an "engine" rich condition. There is only so far the tables can be shifted and lights the CEL lamp to that effect.
Look for bad hoses, anything that will let air into the intake system where it should not..