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Sequential injection vs normal batched?...


yoeddynz
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The engine I am looking at has as standard sequential injection. I might try to keep the stock Ecu for now but eventually will go aftermarket- possibly have a crack at building a megasquirt (MS)

If I do go MS then I have to decide if I want sequential injection or not as this dictates which Ecu I should go for ie $ or $$$

From what I have read sequential is all good- allowing finer tuning and better economy plus possible extra power? I don't know..I am still learning!!

So i asked on a trademe listing for MS and asked about sequential....

'Im i right that this wont manage full sequential injection on v6? If not then how much for ms3 with ms3x? In built up or self assembly. yoeddynz 

Seller replied,

"That's right, it won't handle sequential, but in reality sequential has no performance or economy advantages, it's mainly for emissions. You also need crank and cam angle sensors on the V6 "

Is this bullshit? What's the deal- in fact in laymans terms can someone (Zac?..kpr..?..dave?...) explain sequential and it's benefits...

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Here's a really good explanation.

http://www.carsdirec...s-pros-and-cons

edit: actually, it goes weird near the end so I'll just post the good bits.

sequential fuel injection is a type of multi-port fuel injection system in which each injection valve will open just before the cylinder intake valve opens. So in essence, the individual injectors work by themselves because they are fired individually. Other multi-port systems will fire all the injectors in groups no matter if the cylinder is ready or not. While sequential variable fuel injection has many benefits, direct injection is quickly becoming the system of choice and is replacing the SEFI systems.

Advantages

The main advantage of a sequential system is that the entire system has a fast response time when the driver makes a quick change. More or less fuel can be released when the next intake valve opens. For systems that do not use sequential fuel injection it will be necessary for the entire engine to complete a revolution before the fuel to air ratio can be altered. This type of injection also produces much lower emissions and provides even better fuel economy. Because the fuel is altered for each cylinder, you can potentially get the best performance out of the engine that is possible. The throttle response is immediate, which allows for very rapid changes in the fuel to air mixture. Because fuel is used more economically, the emissions released are lower. This is very important where vehicles are being produced to meet stricter emissions.

Disadvantages

Because there is a single injector for each cylinder, the larger the engine the more expensive the system. A V6 engine will need 6 injectors and a V8 would need 8 injectors. Sequential systems are also more expensive because they require an additional wiring harness that is used to ensure that the injectors pulse sequentially. The electronic control is more complicated and requires additional equipment to run properly. Because the system is more complicated it is very difficult to install and most drivers will require professional installation. This in turn also increases the cost of the system.

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not entirely true

basically above 2000-3000rpm and under heavy load squential operation is not really different to batch fire as the injectors are open the whole time anyway.

at very low rpm there is definitely an economy and probably a power advantage unsure if any response difference would be perceptible.

but at WOT when you give it stick theres negligible difference.

personally I wouldn't bother with full sequential on an aftermarket ecu - to tune it to get those advantages would take a very long time

and running batch fire does not mean bad economy at all. just maybe a few percent worse than sequential at low rpm/low load.

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Yea around the early 90's allot of manufacturers went to sequential, as Tom says it only has advantages in the low RPM range, idle, cruise etc for response and more efficient burn. These cars use the same size injectors as their batch equivalents.

Full sequential on say a race car is more serious again, as rookie says they use resonably oversized low Z injectors, which are usually fairly expensive, there is power to be had with full sequential like this especially with the injector up high in the inlet tract. A few road bikes run full sequential and injectors high in the intake, a good source for awesome injectors for a smaller motor

Anyway as Tom says run batch and be happy

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"sequential fuel injection is a type of multi-port fuel injection system in which each injection valve will open just before the cylinder intake valve opens. So in essence, the individual injectors work by themselves because they are fired individually. Other multi-port systems will fire all the injectors in groups no matter if the cylinder is ready or not."

So with batch do some injectors fire whether or not needed? Sort of like wasted spark? I'm still feeling thick on this one...

Yea around the early 90's allot of manufacturers went to sequential, as Tom says it only has advantages in the low RPM range, idle, cruise etc for response and more efficient burn. These cars use the same size injectors as their batch equivalents.

I'm pretty sure the Mazda k series V6 ecus use sequential. The only thing I will be changing in the install will be getting rid of the stock ugly, heavy, huge inlet manifold and replacing it with a home made individual runners linked to one plenum chamber. Keeping the flanges and injectors in place. The Ecu will only see the vris manifold solenoids missing. Apparantly it'll still run fine according to the mx5 boys using these engines.

So for the sake of extra economy I take it that am I not going to see much benefit by going to aftermarket Ecu (for the cost and time involved)

How effective are the early to mid 90's ecus compared to the latest offerings? Are they archaic or not? What advantages are there, if any, by going after market if keeping a fairly stock engine?

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the thing is most factory ecu's have a very safe mild tune.

I have seen MASSIVE power results just from the fitment if an aftermarket ecu and some decent dunno time ( with a tuner who knows what he is doing)

problem with a mega squirt is that your local tuner might not be familiar with how it works.

if I was doing it I would go visit the dyno shop and ask them what they recommend and are familiar with- any savings on ecu are quickly wasted if the tuner takes a few extra hours working out how to use its features and interface properly

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"sequential fuel injection is a type of multi-port fuel injection system in which each injection valve will open just before the cylinder intake valve opens. So in essence, the individual injectors work by themselves because they are fired individually. Other multi-port systems will fire all the injectors in groups no matter if the cylinder is ready or not."

So with batch do some injectors fire whether or not needed? Sort of like wasted spark? I'm still feeling thick on this one...

Not really like wasted spark, because that would mean (on a V6) you would have pairs of injectors going and you'd end up using twice the fuel you require.

Basically the ecu looks at the parameters of the engine and calculates how much fuel is needed for a complete cycle of the engine (all 6 cylinders firing) and puts that much fuel in with all injectors at once. At lower engine speeds you can see why this isn't ideal, but as Tom and Spence mention, at higher RPM the engine cycles are so fast it doesn't really matter that it only fires all of the injectors at the same time, because even if they were sequential they are basically "on" anyway.

So for the sake of extra economy I take it that am I not going to see much benefit by going to aftermarket Ecu (for the cost and time involved)

How effective are the early to mid 90's ecus compared to the latest offerings? Are they archaic or not? What advantages are there, if any, by going after market if keeping a fairly stock engine?

Late 80's and early 90's ecu's obviously use well outdated technology, but look at what they are trying to do. All they need to be able to do is put the right amount of fuel in at the right time, and fire a spark also at the right time. Granted they can be improved upon, but I don't really think this is what you are after on this build. In my opinion, the money you save in sticking with the original ecu if possible will far out weigh the economy increase in finely tuning the engine on an A/M ecu.

The biggest advantages with aftermarket ecu's is that it allows you to easily make changes to the engine and setup which otherwise are not so easily done with most factory ecu's. You would be able to run throttle bodies and lean the engine right up, a few things like that to make a bit more power and fine tune the engine to run at maximum efficiency.

tldr: try make factory ecu work

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or not needed? Sort of like wasted spark? I'm still feeling thick on this one...

I think you are over thinking this, both batch and sequential essentially supply the the same ammount of fuel to the engine depending on what the ECU/tune and operating conditions dictate. Sequential tries to take advantage of a small gain that can be made by timing the injection event to just before the intake opens, you need a cam angle sensor so you know the engine is on the intake stroke. Batch just says hey lets fire this bank of injectors for x amount of time after this crank angle event, this may be firing on a closed valve but the valves are opening very quicky so this is hardly a big concern. You still have a resonably precise amount of fuel injected for each cylinder, it just may not be perfectly timied for that extra small gain

So you can imagine that as RPM increases it becomes more difficult to deliver the requred amount of fuel in such a small window and sequential becomes harder to implement with cheap equipment. These early 90's port injection sequentail ECU's simply used sequential injection as a easy small % gain they could get in fuel economy and emisions at idle/cruise speeds

Also if a tuner cant use the MS software I would seriously question them, once you set up the initail parameters its simple table tuning. PLus if you are going MS get a wideband, they have become very affordable and you will get the car 99% sorted with a road tune

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My jag runs batch injection. 6 injectors at a time. One bank every 2 revoloutions.

Tis simple as sweet.

The fuel air mix just sits in the runners until its needed. Which at idle, is like 1/4 of a second.

At full song, It makes no difference.

Try and use factory stuff. Otherewise batch fired MS will be quicker, cheaper and easier. And pretty much the same performance as doing a sequential setup.

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Ahhhhhhhhhhhh. Suddenly it became clear.

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Cool. I like that feeling I get when suddenly something that was confusing becomes simple. I shall stick with factory Ecu- this appeals muchly to my wallet.

So this weekend once the eunos is running i shall try my best to isolate the factory Ecu and get it down to just the bare minimum to keep engine running. Once at that point I can remove wiring and engine. Basically try to make the setup as standalone as possible to make life easier when retro fitting it into the viva.

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