Direct Injection: can somebody explain how it is setup

[kingtal0n]

Hello Enthusiasts, I am starting to learn about DI.

before I start through the FactorySManual to see how a DI is setup,

I'd like to hear from knowledgeable folks on the forum first. To kind of get my feet wet with the basics.

Couple of questions to get us started,
What kind of fuel pump(s) go in the tank, or on the engine, or both?
How do they work, i.e. PWM, drivers, control systems involved?
What sort of additional computers are necessary (if any) Does the 1 ECU do 'everything'?
Can you explain how the fuel goes from the tank to the injectors?

And if you are feeling extra saucy,
how does cam timing and injector timing play a role in both factory and added boost application?

thanks

[TCSS07]

I haven't really messed with DI tuning outside the LNF so I probably wont me much help since I never messed with the vvt or injection timing so hopefully someone else can but I can see how it will help with a cammed vehicle which now has changed the valve duration and lift so now the stock injection timing will now be incorrect - i have just tuned normal stuff on some of the V8 DI platform like for cai,tb,intakes,headers,exhaust,afr,tires and such

I can explain how the system works for you though
It has 2 fuel pumps - 1 in the tank like a typical vehicle has to feed fuel to the high pressure fuel pump which is mounted on the cylinder head and is ran off the camshaft fuel pump lobe (some manufacturers make camshafts with a larger lobe to allow for a increase in fuel pressure/flow) by a roller that pushes a spring/pump which then feeds fuel to the injectors
DI requires extremely high fuel pressure to work because the fuel injectors are actually inside the each cylinder spraying fuel - common problem with DI in my experience is that valves are no longer getting fuel sprayed on them which causes carbon buildup on the valves and potentially will cause driveability issues if you don't do proper maintenance like getting a induction service or upper engine cleaning service done ever 30k or so where the cleaner is introduced into the intake manifold whether through the throttle body (mister sprayer - best way imo) or vacuum source (be careful on this method as you can allow to much cleaner to be sucked in and hydro lock the engine) you will need 2 people, 1 in the car holding the rpms up to 3k and the 2nd introducing the cleaner through the vacuum source on the intake manifold with a vacuum hose - don't go to fast but don't go to slow and it'll smoke - the smell/fume always gives me a headache - but after the vacuum port/source method has been performed you let the vehicle sit for about a hour or so in cooler temps to saturate the carbon or if its hot out 2 hours max - you don't want the carbon to harden back up and always do the service (either way) when the vehicle is at operating temp and when your done take the vehicle out and do 3 or 4 wot runs to burn that shit out and it'll smoke like a MF fyi and then finish with oil change when your all done because that shit gets into the oil

Vehicles typically have 2 modules now controlling the fuel system - the fuel pump control module and the ecm
To gain access to the fuel pump control module it must also be licensed like the ecm

[kingtal0n]

Thanks!

Pretty soon I want to help my friend with a 5.3L DI engine (2013-2014) swap into an old car (70's). I'd like to tell him what to grab from the donor vehicle- does he need the fuel control module or can we simply run a typical walbro to feed the DI pump? And anything else he will need that you can recommend? So I can start learning on the engine platform (hopefully this leads to some tuning but the engine is stock so it wont be much)

[Redline MS]

Couple articles on the basics

http://www.superchevy.com/how-to/eng...-get-familiar/

http://www.superchevy.com/how-to/eng...n-the-gen-v-8/

[jpierro79]

ill keep it simple as possible
you have your main feed from tank to a high pressure pump then to your injectors.
the high pressure pump is often driven off of an extra lobe on the cam cause no electrical pump can delivery thousands of psi
the tip of the injectors sit directly in the combustion chamber make it more accurate but changing the injection window from 20 degrees to 6 degrees within optimal timing
the spray is much finer due to higher pressure but remember the pressure is so high to overcome compression. DI requires a return due to high pressures. it is driven just like regular injectors timing and pw difference being requiring more power and containing more pressure and accuracy allowing higher compression and better burn without causing detonation due uneven fuel distribution and temperature in combustion chambers.
in other words its far more accurate just like we start with carburetors, then throttle body injection, then port injection, and now DI.
The problem with DI is you can get enough volume to make 1000hp monster motors so people often combine DI with port to overcome the issue. its much easier to overcome 20 psi in the port side than it is in 200 plus psi in the combustion chamber so thats why you dont see 1000hp DI only motors. We simply cant get enough volume yet. I hope this helps explain reasoning for a few things with DI. The 2018 mustang has a huge advantage for power cause it has facory DI and port injection so they are going to make great power under forced induction applications. high rpm motors are great for turbo applications for spooling turbos. I wish Gm would do it. But the problem is over head cam motors like aluminators the cylinder heads are huge and wide cause the cams and rockers are on top of heads. It makes the overall motor complex bigger but more efficient. Not at low rpm at high rpm. Coyote motors dont have grunt or low rpm torque. Gm trades slightly older design so they can get more displacement into a smaller package. DOD and DI together works bye deactivating cylinders by not having certain valves open under low load so the car runs off halve the cylinders and is more fuel efficient. You cant have DOD and overhead cam.There is no design for it. GM had DOD with DI and variable cam so 6.2 liters in the lt4 making 650 hp is easy for them. You really dont change variable cam timing in a supercharger application cause it wont really benefit much unless you change the cam. Turbo cars on the other hand is another write up.

[kingtal0n]

So I see the pump is PWM driven by the fuel control module,
and it needs some kinda adapter for the 10mm fuel pressure sensor etc..

has anything been done to make this easier yet?

Also curious if an external pump that can be PWM driven at the required flow rate/pressure is available,

The sensor mounting it says "5 to 85* of horizontal to fuel flow" So this basically tells me that almost any angle except near 90* (perpendicular) is acceptable. Just checking? So like 45* is fine?
-> I asked that because in the article they chose 85* exactly for the position. Which makes me wonder why exactly 85 and not 80 or 75* since 85 is so close to 90. And also wondering if there is a 95-175* section as well (does it matter if I am 85* from the left or 85* from the right which would really be 85 + 90 = 175*)

and finally is there such a thing as a GM ECU for 2012-2013 5.3L DI engines that has a fuel control module built in somehow

[Ben Charles]

If you?re worriedabout fuel, keep it simple and just ditch Fpcm and use a simple Warbro or equivalent pump to control the low side...

Low side is simple, high side is where the magic happens

[Ben Charles]

https://www.hotrod.com/articles/518-...ght-crate/amp/

Decent little read toward bottom dealing with fuel