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Old 10-22-2012, 01:25 PM   #15
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You can find most of the codes at this link:
Fuel Injection Technical Library » 3 Digit Self-test Codes 111-171

Attached is a PDF of one persons way of doing an extra fuel pump.
Attached Files
File Type: pdf Dirt Rod's external fuel pump.pdf (299.4 KB, 41 views)
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Old 10-22-2012, 04:57 PM   #16
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Quote:
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But if something is restricting air into the engine like a dirty air filter this will throw the vacuum higher so the MAP sensor will send the wrong signal frequency to the computer and the computer will hold the injectors to ground for the wrong amount of time.
Now higher vacuum will mean less fuel as based on the signal frequency to the engine and it will run leaner with less power. Now the TPS is saying the throttle is wide open so these will be conflicting signals to the computer. I am not sure what the computer will do. It may go back to another look up table and use its values./
That's not what happens if the air filter is restricted. A carburettor meters fuel according to the Volume of air flow. If its air filter is restricted, or if it is at high altitude, it will measure the same volume, but due to the restriction, the mass of air will be less, and so the mass of fuel supplied will be too high, so the carburetted engine runs rich.

An injected system with a mass air flow sensor measures the mass of air flowing through it, so it can compensate for density changes, and keep the ratio of mass of fuel to mass of air correct.

The speed density injection systems that the 460 F53s use rely on the Ideal Gas Law rules that say that mass of air is proportional to pressure of air for every combustion chamber fill. So if a clogged air filter causes reduced air flow, it will also cause reduced Manifold Absolute Pressure, and so th ECU will compute a lower (but correct) mass air flow, and so the mixture will still be correct.

In order that the fuel injector can inject a mass of fuel that is proportional to the duration of the injector pulse, the pressure drop across the injector needs to be constant. That is why we have fuel pressure regulators. As the manifold pressure varies from maybe 6 inches of Mercury to 28 inches of mercury, that manifold pressure is the pressure at the output port of the injector. So to keep the pressure between the input to the injector (the fuel rail) and the output of the injector (the manifold) at a constant 39 psig, we need a fuel pressure regulator that senses that pressure and adjusts the fuel rail pressure accordingly.

So although a restricted air filter could limit the amount of air going into the engine, a fuel injection system operating with a Mass Air system(like the V10 F53), or a Speed Density system(like the 460 F53) will not cause mixture errors.

If the restriction is very bad, then the ECU may well recognize that the TPS and the mass measurement devices are not in agreement, and run off a different sensor from normal.
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Old 10-22-2012, 06:10 PM   #17
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True with a perfect system but I think you missed the point.
The TPS tells the computer how aggressively we want to drive, the computer is programmed to enrich fuel mixtures the further the throttle is opened.
With a restriction in the air cleaner the balance is off and the computer will try to enrich the fuel but there will a lack of air for it with the throttle at WOT.
Who does the computer believe, the MAP sensor or the TPS?

Also what are the sensors your are talking about when you say "run off a different sensor from normal"?
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Old 10-22-2012, 09:21 PM   #18
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True with a perfect system but I think you missed the point.
Hmmm. Well I didn't THINK I did, but lets try again.
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The TPS tells the computer how aggressively we want to drive, the computer is programmed to enrich fuel mixtures the further the throttle is opened.
No, Bill, that isn't what happens. Everybody's gasoline engine ECU evaluate the air mass entering the engine, then evaluates how much of the engine's total air consumption capacity is being used, and then works out what mixture is required for that operating condition, and makes that happen.

With a MAF system, then the MAF is the primary airflow determining sensor, with a Speed Density system it is the MAP sensor, and that about covers street cars. Race cars and motorcycles might use an Alpha N system where the TPS would be primary, but that would be very unlikely on an emissions tested vehicle.

With the 460 Speed Density system, the TPS is NOT primary, and so the mixture is NOT affected as you describe.[/QUOTE]
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With a restriction in the air cleaner the balance is off and the computer will try to enrich the fuel but there will a lack of air for it with the throttle at WOT.
The computer will NOT try to enrich the air because the MAP sensor is Primary, and the MAP sensor is correctly reporting the Manifold Absolute Pressure, and the correct amount of fuel for that air mass is being injected.
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Who does the computer believe, the MAP sensor or the TPS?
As I said in the earlier post, it believes the MAP sesnor for a 460 and the MAF sensor for the V10.

It uses the TPS primarily to detect WOT, or Idle, and to model the injection version of an accelerator pump.

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Also what are the sensors your are talking about when you say "run off a different sensor from normal"?
While MAP or MAF are Primary, the ECUs do have tests to detect malfunctions in those sensors, and if either of those malfunctions are detected, then and only then would the TPS be used as a backup primary means of estimating air flow.
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Old 10-23-2012, 07:07 AM   #19
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I will have to take your word for the above as I have not read the source code for our computers line for line like you have.
I was just going by what I have read in the book by Charles O. Probst, SAE “Ford Fuel Injection & Electronic Engine Control” and on the site OldFuelInjection.com.
I even coped a quote from OldFuelInjection.com that you said was wrong about the TPS so I guess the old saying is true “do not believe everything you read on the Internet”.


Thanks again for the clarification as I always enjoy reading what you have to say about FI on our 460 F53 chassis as I know you have researched it and know what you are talking about.
I was hoping that you would have joined in this post earlier and when did not I made a stab at it.


But as I said above my guess is lack of fuel to the OP engine after the fuel filter. It could be be the fuel filter but I see that replaced a lot over on the other site and it does not fix the problem a lot of the times.
When it does there is a big problem with rust and other junk in the tank with the sock on the bottom of the fuel pump being bad also.
The OP has a 1998 so it came out with the newer style turbine pump and it was to have fixed this problem of lack of fuel. Someone could have replace his fuel pump with older stile pump that all the auto part stores sell. This would have brought the problem back again.


He needs to put a fuel gauge on the fuel rail and drive it to see if it is fuel pressure or not. But he still needs to run all of the Self-Tests to see if any codes come up before he does anything else.
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Old 10-23-2012, 01:20 PM   #20
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I will have to take your word for the above as I have not read the source code for our computers line for line like you have.
I was just going by what I have read in the book by Charles O. Probst, SAE “Ford Fuel Injection & Electronic Engine Control” and on the site OldFuelInjection.com.
I even coped a quote from OldFuelInjection.com that you said was wrong about the TPS so I guess the old saying is true “do not believe everything you read on the Internet”.
That's OK. Which was the OldFuelinjection quote? Maybe I can clarify that. I also have the later revision of the Probst book, so maybe I can also clear that up.

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But as I said above my guess is lack of fuel to the OP engine after the fuel filter. It could be be the fuel filter but I see that replaced a lot over on the other site and it does not fix the problem a lot of the times.

He needs to put a fuel gauge on the fuel rail and drive it to see if it is fuel pressure or not. But he still needs to run all of the Self-Tests to see if any codes come up before he does anything else.
Yes, I suspect this little digression, although interesting didn't help the OP very much. Correct fuel pressure is key to these systems functioning propery, and it is not monitored by the ECU. Later Ford systems used a returnless fuel system where the pump is controlled so as to create an appropriate fuel pressure, but we don't have that on the 460.

So I agree, the OP should attempt to monitor fuel pressure while going up his hill, and he it should always be a constant 39psi above the absolute manifold pressure. Of course the absolute manifold pressure varies while you drive, so your description of what to look for on the gauges we use is pretty good. Wonder how expensive it is to get a differential gauge with 2 hookups for fuel rail and manifold. Then it would be easy to spot these kinds of problems.
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Old 10-23-2012, 01:33 PM   #21
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The OldFuelinjection quote:
"The TPS tells the computer how aggressively we want to drive, the computer is programmed to enrich fuel mixtures the further the throttle is opened."

Maybe OldFuelinjection just copied it from the Probst book.
It was the 1988-1993 Probst book dated 1993.
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Old 10-24-2012, 10:34 AM   #22
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Dam you guys are way above my head.
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