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Old 01-22-2019, 09:11 AM   #1
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Mfi? Idi?

Quick question for you smart people.

If an engine is described as a 7.3L MFI, (which I understand stands for multi-port fuel injection), is that the right engine?

I'm looking at parts and some of the places I'm looking do not have 7.3L IDI on the list, but they do have MFI.
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Old 01-22-2019, 11:15 AM   #2
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MFI would refer to a gasoline engine normally.
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Old 01-22-2019, 11:17 AM   #3
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MFI would refer to a gasoline engine normally.
I don't think there's a 7.3L gasoline engine for a '91 Ford, is there? The specific description is 7.3L MFI.
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Old 01-22-2019, 11:24 AM   #4
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Hard to say if it's a typo, or they mean the powerstroke engine.

What parts are you looking for?
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Old 01-22-2019, 11:25 AM   #5
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Hard to say if it's a typo, or they mean the powerstroke engine.

What parts are you looking for?
Freeze plug heater. I actually found the right one on Amazon but this was the only vehicle description that was even close on two different sites.
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Old 01-22-2019, 11:29 AM   #6
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It could be either the IDI or the Powestroke (T444e).

The year should tell you which one.
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Old 01-22-2019, 11:35 AM   #7
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Quote:
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It could be either the IDI or the Powestroke (T444e).

The year should tell you which one.
Are the blocks different. freeze plugs are pretty standard in size. I would think a freeze plug heater would work in either engine, correct me if I'm wrong.
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Old 01-22-2019, 11:35 AM   #8
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It could be either the IDI or the Powestroke (T444e).

The year should tell you which one.
Yeah, just never saw that "MFI" reference before.

I got what I needed so I'm not going to worry about it.
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Old 01-22-2019, 11:36 AM   #9
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Are the blocks different. freeze plugs are pretty standard in size. I would think a freeze plug heater would work in either engine, correct me if I'm wrong.
That did not turn out to be the case. But I did find the right one.
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Old 01-22-2019, 11:38 AM   #10
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All of my buses & trucks have a single injector for each cylinder.

Sounds like multiport fuel injection to me.......
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Old 01-22-2019, 11:43 AM   #11
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From Wikipedia (which of course doesn't make it right, but there it is):

"An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a prechamber, where combustion begins and then spreads into the main combustion chamber. The prechamber is carefully designed to ensure adequate mixing of the atomized fuel with the compression-heated air."

"Multipoint fuel injection (MPI), also called port fuel injection (PFI), injects fuel into the intake ports just upstream of each cylinder's intake valve, rather than at a central point within an intake manifold."
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Old 01-22-2019, 11:50 AM   #12
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Quote:
Originally Posted by PNW_Steve View Post
All of my buses & trucks have a single injector for each cylinder.

Sounds like multiport fuel injection to me.......
OK I'll call it fuel injected at multiple points. FIMP
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Old 01-22-2019, 12:34 PM   #13
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OK I'll call it fuel injected at multiple points. FIMP
Which is commonly referred to as MPFI.
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Old 01-22-2019, 01:05 PM   #14
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I'm going to call it FIMPFI. Maybe that will be the name of my next bus.
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Old 01-22-2019, 01:28 PM   #15
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MFI cant work in a diesel... IDI does..



in an IDI the pre-chamber is still in the compressed-air of the cylinder.. in an MFI engine, fuel being injected into the intake manifold and not into the cylinder itself..



in a gasoline engine this is OK because the timing of the fire is controlled by the spark plug firing.



in a diesel engine if you injected fuel into the intake, the cylionder would fire way too early and cause power loss or ptemtioal engine damage..



the diesel engine fire timing is controlled by when the fuel shot is injected into the cylinder..



in an IDI there is a small chamber that is connected to the cylinder.. where the fuel goes in.. and then the explosion blows out from that chamber into the cylinder..



in a Direct injection diesel, the fuel is just injected right into the main part of the cylinder..



what works better?? everyone has there reasons for design..



the objective of an engine is to burn fuel and turn it into the most rotational power it can for the amount of fuel burned..



I personally like Computer controlled direct injection.. the flame spread can be controlled by the signal sent to the injector electronically.. but thats me.. im in the minority here.. most like mechanical engines like yours..


-Christopher
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Old 01-22-2019, 01:40 PM   #16
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MFI cant work in a diesel... IDI does..
Well, then, the question remains as to why some auto parts dealers are listing a 1991 Ford E-350 7.3L MFI, when the 7.3 is a diesel engine. I thought those guys might be smarter than me. Seems not.
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Old 01-22-2019, 01:43 PM   #17
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maybe they mix it up with the 460 which in 91 had gone to MFI I believe.. the 460 is technically I think 7.5 liter but ,aybe they list it as a 7.3
-Christopher
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Old 01-22-2019, 01:44 PM   #18
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Quote:
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maybe they mix it up with the 460 which in 91 had gone to MFI I believe.. the 460 is technically I think 7.5 liter but ,aybe they list it as a 7.3
-Christopher
They have 7.5 on the list as well
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Old 01-22-2019, 01:55 PM   #19
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Well, then, the question remains as to why some auto parts dealers are listing a 1991 Ford E-350 7.3L MFI, when the 7.3 is a diesel engine. I thought those guys might be smarter than me. Seems not.
Parts suppliers don't know everything. The windshield wiper lookup book at AutoZone listed the completely wrong size for the rear wiper for my wife's Impreza (like 2 inches and smacking into stuff, too long).
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Old 01-22-2019, 01:58 PM   #20
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Hopefully you got one for a 1.5 inch hole. I believe it's kats #30403.

The heater must go in the rear most passenger side hole. The others won't work because they're cut to use a welch type freeze plug, while the hole you have to use is cut for a cup type plug.

Did you ever check that it didn't have one in it to begin with? I've seen certain times where every engine on the line got a heater. The difference was the ones that ordered it where given the cord to use it.
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