jwsch
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jwsch
I'm having trouble with my 4.6 1997 f150 ford. it is bucking at low speeds checked code with my obd2 and it was po174 lean mix on #2 bank cleaned the map but still no luck check for vacuum leak non found. the bucking and hesitation is at starting out driving at low speed it clears up after 45mph please give me some help thankyou jw
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First begin with what the code means.
A 174 tells you the computer fuel table has shifted to it's lean end out of limits. This causes the code to be set.
It does this 'trying' to correct for an "over rich" fuel condition that is detected by the OX sensor.
The low speed missing would seem to be a flooding condition until the rpm gets high enough to clean out.
Look for some cause of excess fuel.
Excess fuel pressure, leaking/faulty regulator, possible faulty fuel injector on that bank etc.
BTW you didnot clean a MAP sensor because there is none on these motors. You may mean a Mass Air sensor.
Good luck.
A 174 tells you the computer fuel table has shifted to it's lean end out of limits. This causes the code to be set.
It does this 'trying' to correct for an "over rich" fuel condition that is detected by the OX sensor.
The low speed missing would seem to be a flooding condition until the rpm gets high enough to clean out.
Look for some cause of excess fuel.
Excess fuel pressure, leaking/faulty regulator, possible faulty fuel injector on that bank etc.
BTW you didnot clean a MAP sensor because there is none on these motors. You may mean a Mass Air sensor.
Good luck.
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tankyou for your direction with my problem, yes i did mean mass air flow sensor. I will check things out,I'm old schooled ford mechanic, at ford motor company schools many years ago these systems now make me wish that i kept up again many thanks
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Actually, P0174 is set when the fuel trim is at the rich correction limit indicating that bank 2 to is running too lean. Things that can cause this are air leaks after the MAF, vacuum leaks, leaking fuel pressure regulator, low fuel pressure or running out of fuel, contaminated fuel injectors, malfunctioning pcv system, exhaust leaks before the o2 sensor, and leaking egr valve. I would check for air leaks and vacuum leaks that would only affect bank 2 first.
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The rich/lean codes often are the result of 'crossover' conditions before the system settles down to a final code.
It can start as either a rich or a lean condition according to the Ford shop manuel on discriptions of these codes.
I 'guessed' the poster's missfires were the results of an over rich condition until the motor cleaned out at higher rpm but that could be wrong.
This was the basis of assuming the condition was an over rich issue.
The system can sometimes chase it's own tail due to overlapping monitors of system performance until it gets out of limits at some point.
The first limit to be reached dictates the code set and can sometimes be misleading.
It can start as either a rich or a lean condition according to the Ford shop manuel on discriptions of these codes.
I 'guessed' the poster's missfires were the results of an over rich condition until the motor cleaned out at higher rpm but that could be wrong.
This was the basis of assuming the condition was an over rich issue.
The system can sometimes chase it's own tail due to overlapping monitors of system performance until it gets out of limits at some point.
The first limit to be reached dictates the code set and can sometimes be misleading.
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