Newb Question About 3.0 injection

FillMarr · Mar 6, 2018

Learning about fuel injection and I can’t find anything about this. I know my 2003 3.0 Vulcan is fuel injected, but is it direct or indirect injection?

Thanks!

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adsm08 · Mar 6, 2018

Ok, so here is a break down of the types of fuel injection.

There are two major types, as you already noted. Direct and indirect. Indirect has several sub-types.

Direct injection has the injector stuck directly into the cylinder, pointing at the piston, kind of like a spark plug is.

Forms of indirect injection:

Indirect injection as it is used with diesels (DI vs IDI 7.3s for example) still have the injector sticking into the cylinder, but instead of pointing straight at the piston it shoots into a small chamber in the combustion chamber part of the head.

Ported injection, or Multi port injection is when you have multiple injectors (usually one per cylinder) shooting at the back of the intake valve, right at the end of the runner. This is what you have.

Spider injection, is a Chevy-specific stupid version of ported injection. The injectors are in the intake, and each is fed individually by a tube running through the intake. It is called spider injection because the unit kind of looks like a spider.

Throttle body or Central fuel injection (TBI or CFI) is more like a carb than it is fuel injection. You have one or two injectors shooting fuel in at a vertical throttle body, similar to how the jets in a carb work. The only difference there is that rather than rely on venturi vacuum to draw the fuel in you have pressure from the pump pushing it and spraying for better atomization, and the injectors can be opened to closed dynamically so it can effectively re-jet on the go. This eliminates the need for secondaries, primaries, and having to tune the carb periodically.

FillMarr · Mar 6, 2018

"Spider injection, is a Chevy-specific stupid version of ported injection..."

^My favorite part of this.

Thank you so much for this breakdown. I became interested because of an awesome video on Jalopnik: https://jalopnik.com/here-are-the-pros-and-cons-of-direct-injection-1823295996.

My followup question is, how would I have known the Vulcan 3.0 that I have was port indirect injected? I was reading everywhere I could about the Vulcan, but all i ever rear was "Fuel Injected". Is there are "tell" somewhere when reading about engines?

Thanks again,

Phil

adsm08 · Mar 6, 2018

Unless you run across a description that specifies there is usually not a "tell" per se in the spec sheets. Some times you will find "MPI" or "Ported Injection" or "Multi Port Fuel Injection" stamped somewhere on an intake or valve cover.

Almost all diesels are direct injected, as technically even the IDI diesels are still almost DI.

GDI (gas direct inject) systems are almost non-existent before 2010. They started gaining prevalence around then with Ford's Ecoboost setup, and a few other GTDI (gas turbo direct inject) systems from other makers.

Generally a ported system, which is still by far the most common, is easily identified by the relatively small injectors, being on a small rail with push-clip fittings and arranged one per cylinder.

The spider system, which I have only ever seen on a 4.3L would have been a less terrible design if the spider runners had been more durable, but they are easy to damage and hard to replace. It is like a great many other ideas that GM has had and tried over the years, such as side-post batteries, the 3.5L I5, PassKey (the security keys with the resistor chip in them) and "door module" window regulators. They all looked great on paper, but GM manged to build them in a way that made them terrible.

Rearanger · Mar 8, 2018

adsm08 said:
GDI (gas direct inject) systems are almost non-existent before 2010. They started gaining prevalence around then with Ford's Ecoboost setup, and a few other GTDI (gas turbo direct inject) systems from other makers.

My new Sonata is GDI. There is web talk about this type producing more soot in the combustion chamber and dirty intake valve seats as there's no "washing" as the injector fires.

I always thought the fuel needs time to vaporize with the intake air for a better burn.

rusty ol ranger · Mar 8, 2018

Rearanger said:
I always thought the fuel needs time to vaporize with the intake air for a better burn.

It does.

This is why a (properly tuned, and in good shape) carburator would atomize fuel better then any EFI system, besides TBI. The fuel had to travel a long distance through an hot intake manifold to reach the cylinder.

adsm08 · Mar 8, 2018

rusty ol ranger said:
It does.

This is why a (properly tuned, and in good shape) carburator would atomize fuel better then any EFI system, besides TBI. The fuel had to travel a long distance through an hot intake manifold to reach the cylinder.

Yes, that is why EFI runs so much cleaner and more efficiently across a much wider range of conditions than any carb ever could.

Face it, carbs suck and it isn't just because of the venturii effect. There is no metric by which they are superior to an EFI system, especially an OBD2 one, and the only reason we used them for as long as we did is because that was the best we could do with the technology we had.

Carbs atomize fuel in exactly the way Rusty says, and it works. They push low pressure fuel into the jets and let the heat and distance atomize the fuel. That is also why there are performance gains to be had by using a throttle body spacer with a carb.

EFI does it differently. It pushes high pressure fuel through 3 or 4 smaller openings right at the valve. This is actually a very efficient way to deliver a precisely metered amount of fuel to an individual cylinder and, generally avoids issues like fuel pooling in the intake, cold start problems, and uneven delivery.

Most carbs run fuel pressure between 5 and 10 PSI. Early EFI systems ran about 35, and modern ported injection runs around 70. GDI systems can have upwards of 3000 PSI at the injector. Going from high pressure to low pressure through a small restricted orifice does wonders for atomization.

GDI systems do have issues with carbon build up on the back of the intake valve because on a ported system the injector spray does wash the valve. This is why early and frequent induction services are important on GDI engines. It is also why a lot of manufacturers with GDI are starting to use a "dual fuel" system where they have ported injection running when full power is not needed, then switch to the direct injectors at high load.

fastpakr · Mar 8, 2018

rusty ol ranger said:
It does.

This is why a (properly tuned, and in good shape) carburator would atomize fuel better then any EFI system, besides TBI. The fuel had to travel a long distance through an hot intake manifold to reach the cylinder.

Rearanger · Mar 8, 2018

adsm08 said:
This is why early and frequent induction services are important on GDI engines.

So using an intake applied valve and cylinder cleaner would work - like "Mopar Combustion Chamber Cleaner"?

My owner's manual just states "fuel additive" at every 7500 miles. I use Red Line SI-1.

rusty ol ranger · Mar 8, 2018

Actually, carbs are superior in the fact they are easy to work on. I can tear down and put back togther a 2150 motorcraft in 30 minutes and spend 15 of those looking for a screwdriver.

Im not here to argue the merits of which is better, and i dont know really how well DI atomizes fuel, however, regular port i njection is inferior to a carb when it comes to fuel atomization. They make up for this by being able to adjust "on the fly" to changine load conditions.

Personally, im indifferent to EFI or carb, ive just ALWAYS had better luck with carbs, my 77 will start and run in the cold just as good as my wifes escape. I will admit, EFI does run cleaner and is eaiser for the latte sippers of today to operate.

ericbphoto · Mar 8, 2018

"I can tear down and put back togther a 2150 motorcraft in 30 minutes and spend 15 of those looking for a screwdriver."

That is awesome for you. But, here in the 21st century, you are part of an ever-decreasing minority. For the rest of us, a good fuel injection system is the way to go.

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fastpakr · Mar 8, 2018

rusty ol ranger said:
Im not here to argue the merits of which is better, and i dont know really how well DI atomizes fuel, however, regular port i njection is inferior to a carb when it comes to fuel atomization. They make up for this by being able to adjust "on the fly" to changine load conditions.

The idea that carburetors create better fuel atomization is categorically false. It's not a matter of opinion, just the reality of higher fuel pressure and nozzle design at work.

rusty ol ranger · Mar 8, 2018

ericbphoto said:
"I can tear down and put back togther a 2150 motorcraft in 30 minutes and spend 15 of those looking for a screwdriver."

That is awesome for you. But, here in the 21st century, you are part of an ever-decreasing minority. For the rest of us, a good fuel injection system is the way to go.

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Thats fine and dandy for the majority. Just means parts are cheaper for me. When something fails in your EFI system (lets say, a fuel pump), youre dead in the water. Carbs can usually be "patched" well enough to get you home. If im on a trail somewhere then i see this as a huge asset.

Fast,
Exactly how? A carb jet sprays somewhat of a mist as it is, then the fuel rides thru a hot intake for 8 or 10 inches, allowing further evaporation of liquid, leaving less liquid hitting the cylinder and more vapor.

An port injection travels not even half the distance, therefore having less time to evaporate into vapor.

adsm08 · Mar 8, 2018

rusty ol ranger said:
Thats fine and dandy for the majority. Just means parts are cheaper for me. When something fails in your EFI system (lets say, a fuel pump), youre dead in the water. Carbs can usually be "patched" well enough to get you home. If im on a trail somewhere then i see this as a huge asset.

Fast,
Exactly how? A carb jet sprays somewhat of a mist as it is, then the fuel rides thru a hot intake for 8 or 10 inches, allowing further evaporation of liquid, leaving less liquid hitting the cylinder and more vapor.

An port injection travels not even half the distance, therefore having less time to evaporate into vapor.

Vaporization is not atomization. Vaporization turns a liquid to a vapor. Atomization turns a liquid to a fine mist.

Additionally dropping pressure quickly (the 35 to 70 PSI fuel rail into the intake manifold that is under vacuum) causes vaporization. This is the entire reason that air conditioning works. The refrigerant is under high pressure coming out of the compressor, it gets pushed up against the orifice tube and then as it goes through there it drops pressure drastically on the suction side and turns into a gas. The pressures involved in AC are a lot different than EFI, but that is because AC refrigerant is already a gas at room temperature, gasoline is not, and we are not trying to make the gas cold.

FillMarr · Mar 8, 2018

This is the most active thread I’ve ever started in my life, so thank you everyone for the input.

I have been looking at other Rangers to replace mine, which is high on heart but low on power ...thanks to the 3.0 and a slight manifold exhaust leak. I could rebuild the head, and I might, but it would be my first time and I’d probably still be disappointed with the power out put.

But now Rusty Old Ranger now has me thinking about getting one of the old boxy Rangers (1990?). And his comment reminds me, nothing sounds more bad ass than those old carb’d engines. That’s +1 for the carbs for sure!

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Newb Question About 3.0 injection

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