MAP sensor
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From: Detroit Subs
A MAP sensor measures the Manifold Absolute Pressure (hence MAP) and is a means of determining an engine's load condition.
A high vacuum is a low manifold absolute pressure. The two are inversely related, so under high load, you have a low vacuum and high manifold absolute pressure. It is normally found after an engine's throttle body, just before or on the intake manifold. I don't know where it's specifically located on the 7.3L.
A high vacuum is a low manifold absolute pressure. The two are inversely related, so under high load, you have a low vacuum and high manifold absolute pressure. It is normally found after an engine's throttle body, just before or on the intake manifold. I don't know where it's specifically located on the 7.3L.
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From: Detroit Subs
Originally posted by gburkett
Thanks guys, I appreciate the reply. How much does it have to do with the fuel milage?
Thanks guys, I appreciate the reply. How much does it have to do with the fuel milage?
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Joined: May 2001
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From: Cabot, Arkansas
A couple of diesel specific points that I think are applicable to this thread.
1. There is no throttle body.
2. There is no vaccuum, only pressure.
3. Diesels always run lean.
On the PSD the MAP sensors basic function is to measure the engine load via the amount of boost being produced and send that info to the PCM so that it can adjust the fuel curve accordingly. It's possible that a "slightly bad" MAP sensor could affect the milage, but I would think there would be other, more severe symptoms associated with it. Bad idle, poor running, lack of power, check engine light....that sort of thing.
1. There is no throttle body.
2. There is no vaccuum, only pressure.
3. Diesels always run lean.
On the PSD the MAP sensors basic function is to measure the engine load via the amount of boost being produced and send that info to the PCM so that it can adjust the fuel curve accordingly. It's possible that a "slightly bad" MAP sensor could affect the milage, but I would think there would be other, more severe symptoms associated with it. Bad idle, poor running, lack of power, check engine light....that sort of thing.
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Joined: Apr 2003
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From: idaho
Would an air leak in the line also cause the milage to go down? meybe I'm crazy or just don't know what it's suppose to sound like but the engine sounds like it's getting air in the line to the injectors. is there a way to tell if you have an air leak in the fuel lines? I appreciate the help from everyone, makes this forum great!
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From: Central PA
Originally posted by gburkett
Would an air leak in the line also cause the milage to go down? meybe I'm crazy or just don't know what it's suppose to sound like but the engine sounds like it's getting air in the line to the injectors. is there a way to tell if you have an air leak in the fuel lines? I appreciate the help from everyone, makes this forum great!
Would an air leak in the line also cause the milage to go down? meybe I'm crazy or just don't know what it's suppose to sound like but the engine sounds like it's getting air in the line to the injectors. is there a way to tell if you have an air leak in the fuel lines? I appreciate the help from everyone, makes this forum great!
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From: Cabot, Arkansas
What year is the truck? If it's a Superduty with a stock fuel system then it is very likely that the fuel system is drawing air.
Do a search for "tank mods" and "pre-pump mod" and let us know if the descriptions found there in are similar to your situation.
How poor is the milage that spawned the thread?
Do a search for "tank mods" and "pre-pump mod" and let us know if the descriptions found there in are similar to your situation.
How poor is the milage that spawned the thread?
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Senior User
Joined: Apr 2003
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From: idaho
Cookie, I have a 01 crew, 4x4. I have done the fuel tank mods and put the inline filter on and changed the clamps like the mod says to. When I bought the truck I was getting about 16mpg. Now I can't get better than 13.5mpg. I have the stinger w/chip and a 203 thermostat so I thought I would be getting better than this! The sounds isn't a hiss or anything.....just sounds like it's missing at low speeds. to me it sounds like it would if there was air in the line but I have no smoke out the exhaust either. I did talk to the dealer once and was told that this was normal milage but I have seen to many others to know that this isn't true. Oh, by the way, I do drive conservately (most of the time).
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Joined: May 2001
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From: Cabot, Arkansas
Is it still cold in Idaho? Might just be winter fuel. Mine got low 15's for the last couple months, but with the return of summer fuel down south it's back to the mid 17's the last 2+ tanks.
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