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injecting on close valves

stonie

stonie

New member
Joined
Apr 3, 2016
Location
Switzerland
looking on lh 2.4 wiring diagrams, all 4 injectors are connected to 1 signal, that means all injectors are injecting all the time also when the valves are closed!? what happends to this fuel and why is this system working like that? only cooling?

maybe im to stupid for the diagram...
 
How many time per second does that valve open and close with the engine turning 5000 rpm?

Does the air flow really stop and start that quickly?

You are reading it right, its called batch fire, and somehow it seems to work...
 
megulon-7 said:
How many time per second does that valve open and close with the engine turning 5000 rpm?

Does the air flow really stop and start that quickly?

You are reading it right, its called batch fire, and somehow it seems to work...
Click to expand...

83times a minute with " batch fire "

41.5 imho would be enough :-P
 
Yeah it's called batch fire......

Carbs can dump fuel even when the engine isn't running with a pumper. They also manage to work.
 
Sequential injection is good for emissions, maybe some better idle, startup I think ECU's on the new stuff read the cam position sensor and inject fuel in to the open valves for a quicker start....better low speed stuff? Doesn't matter that much, run a boosted engine with decapped injectors on batch fire and it'll run just fine lol. Sequential ignition on the other hand...that's some good stuff for hot sparks lighting off rich mixes!
 
Every single modern OEM sequential port injected engine I've worked with completes the injection event on a closed valve. This is far more beneficial at lower loads and engine speeds than injecting on an open valve.

There's nothing magical about batch fire injection. It's metered fuel just like any other method of delivering fuel to the engine.
 
Interesting stuff! I'd like to learn more about modern ECU's and engines, I got into this stuff late in the game and man there is alot to absorb! With injecting on a closed valve, what does it accomplish?
 
Tentshedtrev said:
Interesting stuff! I'd like to learn more about modern ECU's and engines, I got into this stuff late in the game and man there is alot to absorb! With injecting on a closed valve, what does it accomplish?
Click to expand...

A few things:

When an engine is at operating temp the intake valve is quite hot. By injecting fuel on a hot intake valve before it opens the fuel is further vaporized before it enters the chamber.

The fuel that doesn't get further vaporized, or when the engine is cold, the moment the valve comes off the seat there's a high velocity shear as the valve begins to open. This shear will atomized fuel effectively.

Injecting across an open valve at low speeds or loads usually results in poor fuel atomization and distribution within the chamber.

This doesn't work well with engines that have cams with significant overlap as some of the fuel charge is scavenged through the exhaust valve during overlap. In this case you delay the injection event until the exhaust valve is closed.
 
thanks for your answers , the reason why im asking this is because im actually installing MaxxEcu on my project and i was wondering if i should wire each injector and programm it sequential or should let it like it is?
 
If you go through the cost and work of installing an ecu i would add those 4 wires.
The Maxxecu also monitors current per injector and trims fuel per injector via EGT (per port, if you have the sensors) so it would be quite good to wire it up already.
But thats mostly gathered from reading the Maxx manual. No experience with making it work yet. Thinking of buying a Maxxecu as well.
 
JW240 said:
If you go through the cost and work of installing an ecu i would add those 4 wires.
The Maxxecu also monitors current per injector and trims fuel per injector via EGT (per port, if you have the sensors) so it would be quite good to wire it up already.
But thats mostly gathered from reading the Maxx manual. No experience with making it work yet. Thinking of buying a Maxxecu as well.
Click to expand...



good point,

the thing is i want to let original harness like it is for the posibility to plug lh 2.4 ecu in and car is still working (because of the law in my country)
 
stonie said:
thanks for your answers , the reason why im asking this is because im actually installing MaxxEcu on my project and i was wondering if i should wire each injector and programm it sequential or should let it like it is?
Click to expand...

stonie said:
good point,

the thing is i want to let original harness like it is for the posibility to plug lh 2.4 ecu in and car is still working (because of the law in my country)
Click to expand...

??? If you are installing an aftermarket EMS, you will already be making changes to the system... If your intention was to make bridge connectors to go from the LH2.4 and EZK ECU connectors (to keep the bay wiring stock), then splitting out the injector feeds with a relay or other control circuit that will revert to batch fire (single feed) when you plug the LH back in, should be relatively simple.

If you have no clue how to go about any of this, you have much more research to do, and studying of the stock wiring schematics to determine the best way to interface your new EMS...
 
As already mentioned, spraying fuel on a warm (when the engine is running) closed valve gives the fuel more time to atomize.

Although 'time' is a rather relative term. It's not 83 times a minute. At 1000 rpm idle, that's 500 combustion events per minute per cylinder (2 complete rotations to complete the 4 stroke cycle), which is 8.3 per second. Rev it up a bit and it really becomes rather meaningless where exactly in the 2 rotations per cylinder firing the injector fires.

I have my 245 wired up sequentially, so with a click or two in Tuner Studio I can change it from batch to sequential, and in sequential mode I can alter the timing of the injection pretty much over the whole 720 degrees. I messed around with that some not long after I got the car running on the new setup (MS3X and coil on plugs and DSM CAS) and really couldn't tell much of a difference even at idle. Might make more of a difference on a cold start, but I haven't had the time or inclination to worry much about that (beyond the basic 'it starts without drama when its cold'.

I'm pretty sure (but not absolutely) that Bosch LH is firing multiple times over the course of all 4 cylinders firing, even though all 4 cylinders get spritzed at the same time. I think it's 4 times per 2 rotations, though, maybe 2? So all 4 cylinders get the same pattern of spritzes - 3 on a closed valve, 1 on an open valve (or very close to it).
 
ill plug the maxx ecu in the original plug from lh and add some wires for MAF etc.

car should work also when i remove maxxecu and plug in back oem Lh ECU

think ill stay on batch fire, cant read any disadvantage out of you guys posts.
 
CAPT_BLOTTO said:
Yeah it's called batch fire......

Carbs can dump fuel even when the engine isn't running with a pumper. They also manage to work.
Click to expand...

More to the point, they worked and passed US and other emissions standards for cold start and running...and engines racked up hundreds of thousands of happy mile..or kms as the case may be.
Obviously no major detriment batch or sequential...probably no concrete reasons why one or the other like a million other either/ors in life..
 
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