Confused
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Confused
Just replaced the head gaskets on my 97 f150. It runs, but is missing!
Replaced the plugs, wires and coils. Still a miss on bank 1 side (p0171 code).
Now, the only things I haven't tried are pulling the plugs to ensure proper gap. And there's a broken manifold stud on that side. With a pretty good leak. Now, would a leak before the 02 sensor cause it to read lean enough to dump excessive fuel, and cause a miss?
Very frustrating.
Oh, and it's a 4.6. Vin code 6.
Replaced the plugs, wires and coils. Still a miss on bank 1 side (p0171 code).
Now, the only things I haven't tried are pulling the plugs to ensure proper gap. And there's a broken manifold stud on that side. With a pretty good leak. Now, would a leak before the 02 sensor cause it to read lean enough to dump excessive fuel, and cause a miss?
Very frustrating.
Oh, and it's a 4.6. Vin code 6.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
That's why the code is set.
Believe in what it tells you.
Fuel injection and ignition timing are updated for every cylinder on a seperate basis for every power stroke revolutuon.
The system is that fast reacting.
Matter of fact, the distance the OX sensors are from the head ports in the manifold is a designed in distance.
This is so it can include all cylinders distances within for a reasonable amount of time for the system's reaction for corrections it makes for each cylinder's fuel and ignition timing.
Those people who change OX sensor locations in tube headers placing them farther down the line or install them in one of the tubes actually upset the feed back timing of the system as well as the temperature they operate at..
Bottom line is the OX sensors must see a very close average exhaust content for all the cylinders to have good overall system accuracy so some cylinders don't go lean and some go richer than they should operate at.
.
Last items are when you look at the spark plugs in a good running motor, they will look whitesh because of this very tight total system control of fuel mixtures.
If a missfire code is set for a cylinder, it tells you the crank sensor fed back a 'timed' signal to the PCM for that cylinder that was to 'slow rotation' indicating the cylinder is not making the same average power as compaired to the average of all the other cylinders.
It does this by compairing the time to a table in software.
Out of limits = a code set after it's 'logics' the misfire is a permant event.
Very clever, them Ford engineers, huh?
I know it's more than you asked for but it may be of interest to others.
Good luck.
Believe in what it tells you.
Fuel injection and ignition timing are updated for every cylinder on a seperate basis for every power stroke revolutuon.
The system is that fast reacting.
Matter of fact, the distance the OX sensors are from the head ports in the manifold is a designed in distance.
This is so it can include all cylinders distances within for a reasonable amount of time for the system's reaction for corrections it makes for each cylinder's fuel and ignition timing.
Those people who change OX sensor locations in tube headers placing them farther down the line or install them in one of the tubes actually upset the feed back timing of the system as well as the temperature they operate at..
Bottom line is the OX sensors must see a very close average exhaust content for all the cylinders to have good overall system accuracy so some cylinders don't go lean and some go richer than they should operate at.
.
Last items are when you look at the spark plugs in a good running motor, they will look whitesh because of this very tight total system control of fuel mixtures.
If a missfire code is set for a cylinder, it tells you the crank sensor fed back a 'timed' signal to the PCM for that cylinder that was to 'slow rotation' indicating the cylinder is not making the same average power as compaired to the average of all the other cylinders.
It does this by compairing the time to a table in software.
Out of limits = a code set after it's 'logics' the misfire is a permant event.
Very clever, them Ford engineers, huh?
I know it's more than you asked for but it may be of interest to others.
Good luck.
Senior User
Joined: Dec 2011
Posts: 484
Likes: 0
From: Rockland Ontario
That's why the code is set.
Believe in what it tells you.
Fuel injection and ignition timing are updated for every cylinder on a seperate basis for every power stroke revolutuon.
The system is that fast reacting.
Matter of fact, the distance the OX sensors are from the head ports in the manifold is a designed in distance.
This is so it can include all cylinders distances within for a reasonable amount of time for the system's reaction for corrections it makes for each cylinder's fuel and ignition timing.
Those people who change OX sensor locations in tube headers placing them farther down the line or install them in one of the tubes actually upset the feed back timing of the system as well as the temperature they operate at..
Bottom line is the OX sensors must see a very close average exhaust content for all the cylinders to have good overall system accuracy so some cylinders don't go lean and some go richer than they should operate at.
.
Last items are when you look at the spark plugs in a good running motor, they will look whitesh because of this very tight total system control of fuel mixtures.
If a missfire code is set for a cylinder, it tells you the crank sensor fed back a 'timed' signal to the PCM for that cylinder that was to 'slow rotation' indicating the cylinder is not making the same average power as compaired to the average of all the other cylinders.
It does this by compairing the time to a table in software.
Out of limits = a code set after it's 'logics' the misfire is a permant event.
Very clever, them Ford engineers, huh?
I know it's more than you asked for but it may be of interest to others.
Good luck.
Believe in what it tells you.
Fuel injection and ignition timing are updated for every cylinder on a seperate basis for every power stroke revolutuon.
The system is that fast reacting.
Matter of fact, the distance the OX sensors are from the head ports in the manifold is a designed in distance.
This is so it can include all cylinders distances within for a reasonable amount of time for the system's reaction for corrections it makes for each cylinder's fuel and ignition timing.
Those people who change OX sensor locations in tube headers placing them farther down the line or install them in one of the tubes actually upset the feed back timing of the system as well as the temperature they operate at..
Bottom line is the OX sensors must see a very close average exhaust content for all the cylinders to have good overall system accuracy so some cylinders don't go lean and some go richer than they should operate at.
.
Last items are when you look at the spark plugs in a good running motor, they will look whitesh because of this very tight total system control of fuel mixtures.
If a missfire code is set for a cylinder, it tells you the crank sensor fed back a 'timed' signal to the PCM for that cylinder that was to 'slow rotation' indicating the cylinder is not making the same average power as compaired to the average of all the other cylinders.
It does this by compairing the time to a table in software.
Out of limits = a code set after it's 'logics' the misfire is a permant event.
Very clever, them Ford engineers, huh?
I know it's more than you asked for but it may be of interest to others.
Good luck.
Thanks.
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