Four injection units used to be demanded few in the market that turbo and super chargers captured the shares of.
However, four injection units are bang these days among a great number of users.
Absolutely, even though the injection becomes more popular, not so many people seem to understand its features and works precisely.
As the result of it, a lot of users put questions to us on the injection units almost everyday.
Less knowledge often makes us anxious.
Now, Maruha will tell you the features and functions that four injection units have, though some tuning magazines and internet sites never point out.
Maruha Four Injection Units are free from user’s anxiety and troublesome.
An engine and four injection units have a close connection.
If you tune NA engines, how will you power up your car?
When it comes to increasing car power, you will hit on the idea of producing a strong spark, highly compressing an engine and sending more air into the engine.
Actually, we can increase a compression ratio by grinding an engine head, blowing the bore up or enlarging a piston crown area.
However, even if you improve your engine’s performance, there is no worth doing this in case of it cannot let enough air into the engine.
That is, enhancing the engine performance means that more fresh air can be sent into the engine.
Four injection units play a role of sending more air into it than normal throttle bodies.
It is useful to install a high camshaft to power up your car.
Engine performance is improved by increasing camshaft duration and a cam lift.
But unfortunately, whatever high performance camshafts you have, they never offer you the maximum engine performance.
For instance, a normal B6 engine with a high camshaft, which duration is an angle of 288 degrees, cannot work well in the mid to high RPM ranges, even if the engine reaches the highest RPM range at a stroke.
A normal surge tank causes this trouble.
It is unable to send enough air into the engine and is hard to let your car maximize its performance because of a total lack of air that is necessary in the high RPM ranges.
However, the air shortage is totally solved when you replace with four injection units.
These contexts tell you that ideal engine performance is available, only if a high camshaft and quad injections are used together.
Both of them are a match made in heaven like an athlete and his or her coach who can bring out hidden potential of him or her.
We do not doubt that four injection units are a part to power up our cars.
But in order to use them on the street, you would face problems such as an unstable idling condition and becoming a gas guzzler.
Therefore, it is the wisest choice to beat a rumor that all of four injection units can make cool street drive, at the same time, and that they run speedily to the high RPM ranges because the units are a tool for increasing your car’s power.
Unless it gains stable idling and lesser fuel costs, you can never get four injection units that are suitable for street drive.
In order to make four injection units more useful in street drive, to begin with, we have to control idle speed.
Idle should remain stable under variable conditions such as heat at engine start up, A/C idle up and some effects due to current consumer electric devices.
A carburetor is impossible to match exactly these conditions because fine adjustment of a flap is the only one thing to control the idling.
An idle adjust screw moves the flap up subtly to set the idling. However, there are several changes such as water temperature and loads of A/C or of lights.
Except for the control by the ECU, the air travels through an air bypass valve under heavy loads or we can use a diaphragm that forces a throttle to open slightly.
But these techniques are cheap skills in order to reach rough expected idling speed.
That is the reason why they are inferior to the control by the ECU.
The control by the ECU means that it moves the air bypass valve with a solenoid valve to approach the expected idling speed that has been already programmed. This control system is adopted with genuine MIATA engines to improve expected idling by controlling idle speed properly under every situation.
There are a limited number of four injection units that are controlled idle speed by solenoid valves.
The most of them set their idle by adjusting flaps subtly and also can reduce loads by changing ignition timing.
Some products tend to cause engine stop and rough & high idling because
they are totally unable to control their idle conditions.
The existence of these useless injections makes many users assume that four injection units are hard to be handled.
It is very welcomed to upgrade your car with more comfort by installing four injection units, but if you find them as gas guzzlers, they will waste resources and your money.
Actually, four injection units tend to increase your car’s power, while they consume more gas than a normal injection system.
This stone wall faced and annoyed us during we have developed our product.
It would be easy to think that less emission from injections can achieve fuel efficiency.
However, it causes a lack of car’s power, a heavy pickup in shifting, unstable idling and a stall.
Constant acceleration resulted from cutting gas consumption robs you of enjoyable cool drive brought by four injection units.
Maruha can solve the hard problems by finely controlling the amount of the emission under the ECU program.
Our injection units can bring you a more powerful and economical drive.
It means that you do not need to worry about the fuel cost in sport drive.
ECU, including a sub computer and a full computer, plays a very important role in four injection units.
Sub computers have an advantage in their low prices and ease of use.
Low price-oriented customers will accept them as tuning items.
They also have a disadvantage.
It is impossible to control injection systems precisely, unlike full computers do because they have different specifications.
Sub computers send dummy signals to genuine ECUs, while full computers make engines run following programmed data.
That is, sub computers force the ECUs to be controlled broadly by altering data with revolution ranges that are roughly allotted.
These computers cannot make fine control.
Conversely, they also have a reason to exist in the world.
When you input data into full computers, personal computers or command interpreters are essential, while sub computers can be changed their settings only by turning the dials.
They control four injection units at a rough level, but it is not enough to control quad injections for street drive.
The Freedom ECU, which is one of full computers, deals with specific engines and also has couplers and functions that correspond to the engines.
In these points, the Freedom ECU is easier to be handled than the other all-purpose products.
As we mentioned earlier, a full computer has to be input data.
It is difficult to program following engine specifications.
Needless to say, unless the programming is completed, the engine cannot work and your car is never powered up.
Programming is the biggest key to powering up cars.
Generally, people say that full computers are pricey, even though the Freedom ECU has a reasonable price.
That is the reason why the latter is accepted in the market.
However, it is not a state-of-the-art computer as it does not deal with 3D programming.
In addition to this, it has particular features corresponding to specific engines and it is far from an all-purpose ECU to apply to other cars.
It is welcomed for full computers to serve us space to program what we need by ourselves, but some manufacturers never allow to program their ECU unless people pay high contract payments.
In order to get enough power with four injection units, it is important to select an individual running throttle body (IRTB) cleverly.
You would not have any problem when you choose an IRTB which diameter is suitable for your car’s displacement and tuning contents, but the other hand we have a problem.
IRTBs which diameters are 43.0mm or 45.0mm are generally used, while they are slightly large in some cases.
Maruha recommends you a 40.0mm IRTB that can make enough power in B6 and BP series.
The diameter is also suitable for stable idling and a drive in the low RPM ranges.
Our IRTB line includes 40.0mm, 42.0mm, 45.0mm, 48.0mm and 50.0mm of diameters to match your needs.
First and foremost you have to keep balances among flaps when you install IRTBs in your car.
As Maruha’s IRTBs are the twin choke type, you need to have 2 IRTBs. All you do is adjust a linkage between them.
On the other hand, IRTBs made by other manufacturers are necessary to be adjusted each of them because they are the single choke type.
It is hard to keep their balances as they are linked with pillow rods.
In case of being linked with throttle pulleys, it is more difficult to be balanced because of their complicated specifications.
Genuine injectors and solenoid valves make wiring easy.
You have to wire electrical parts such as an injector, a throttle position sensor (TPS), a controlled combustion system and a vacuum sensor (PIM) because Maruha’s IRTB is totally controlled by the Freedom ECU.
Whenever you use electrical parts excluding the genuines, electrical wiring should be done.
Patient and careful work will bring less problems, but actually many people tend to mistake how to connect up.
For example, electro-tap connectors cause contact failure.
Bad connections would be possible to damage ECUs and you may waste time to locate sources of trouble.
Wiring should have a simple specification.
Our products are suitable for couplers by means of the Freedom ECU for the MIATA only.
You do not have to wire up. The solenoid valve for idle control and the injector are the genuines.
The throttle position sensor and the other sensors have wiring tags in order to wire up easily.
Maruha’s IRTB is proud of its wiring specification that will be the easiest-handling kit in the world.
Simple wiring means easy replacement.
In case of parting with your own car, it is not difficult to restore its genuine state by detaching the IRTBs.
SIMPLE IS BEST.
You know that ECU programs are the keys to success in driving four injection units effectively. (In detail, see “ 5. ECUs and their strong & weak points” page.)
In order to maintain the quality of the ECU system, Maruha allots serial numbers to all of our ECUs.
The numbers allow us to find information related with each of the ECUs: sold to whom, date of purchase, which specification we sold to the customer.
We have big reason to save the information around our product, that is, we need to protect the data that our ECU contents.
Because it is programmed on the basis of our four injection units, copied data will be unsuitable for other quad systems.
If you give your ECU to someone else, we can match the next user’s needs following the information.
Maruha’s ECU is aimed at users who love programming by yourself.
It has 4 channels and 3 of them are prepared as “Power Mode”, “Economy Mode” and “Circuit Mode”, which are initially programmed before we release the Freedom ECU to the market.
D Control System (DCS), which computing is based on a vacuum sensor, is used among a large number of economy cars.
The ECU calculates how much air the vacuum sensor includes.
There are several measurement methods for air inflow.
For instance, DCS computes the amount of air under manifold pressure.
DCS has an advantage of stable idling, even though it responses little slowly in severe conditions such as races because the manifold pressure is changeable whenever throttles are open.
Throttle position control is a good solution to this problem.
It can response immediately by adjusting the amount of air according to the opening angles of the throttle valves.
However, you have to bear in mind that the throttle position control also has a disadvantage of idling control.
We recommend using Circuit Mode under race situations.
The vacant channel is placed for customers who plan to program following your intention.
Programming on the basis of Maruha’s initial programs would prevent your engine blowing caused by programming failures.
You can arrange these 4 channels by adjusting the dials on the ECU with small screwdrivers.
If you need sensors when you buy Maruha’s four injection units, we can offer you them at about 1/20 price than products spread over the market.
The reason we sell them at very low prices is that they are widely-used and second-hand sensors that we have stocked.
For your information, it costs $170, more or less when you buy a new product.
It is natural to think that you might be worried if these used sensors fulfill safety standards of if they work properly.
CHILL OUT! We examine their performances carefully before the products are released.
Furthermore, we also sell couplers that are suitable for the sensors.
Connect tags are attached to them in order that you can wire up smoothly.
Our controlled combustion sensor and vacuum sensor are really good deals.
You will be fulfilled with their low prices and high quality.
Maruha Four Injection Units Price Table
| Product | Price |
| System kit for NA6CE | |
| System kit for NA8C (before M/C) | |
| System kit for NA8C (after M/C) | |
| WindowsR software cable | |
| Options: | |
| Controlled combustion sensor (USED) | |
| Vacuum sensor (PIM) (USED) | |
| Fuel Socks Air | |
| Cleaner Set (4 cleaners contained) |
Contains of Maruha Four Injection Units
| intake manifold | fuel regulator |
| fuel delivery pipe | throttle linkage set |
| vacuum block | the Freedom ECU |
| O-ring for the genuine | injectors 1 set of hoses |
| throttle body (IRTB) | 1 set of stays |
| throttle sensor | 1 set of bolts AND nuts |
| idle control block | hole plug for the genuine |
| air funnel | injector(for B6 engine model only) |
| manifold insulator |
The price and content tables can show you that our four injection units include the essential parts and that Maruha provides our products with other necessary options.
When you need to know the full cost roughly, you only have to check up the price table or contact us.
The table is clear accounting.
We avoid vague pricing methods such as camouflaging products as inexpensive ones by showing prices of main parts without notifying the other parts prices at all.
We never cheat you.
Maruha is convinced that our products and services will fulfill your needs.
The content table will help you to understand how our four injection units work.
Some of our customers try to fix their four injection units single-handedly to save the expenses.
They often ask us a question, “You know, can I install my injections without your help?” Whenever we hear the words, our hearts begin to beat too fast as there is a chance of serious accidents or bad performances.
Although an instruction book is available, our four injection units are designed and manufactured on the premises that skilled mechanics install our product at well-equipped workrooms.
Only their skills and experiences can adjust accurately the engine condition and the balance of the IRTBs.
We urge you to install Maruha Four Injection Units at pro shops.
An uncovered funnel has good and bad points.
It really looks hip, on the other hand, it is dangerous as dust and dirt easily blow into the funnel.
In order to prevent the damage, we recommend you to cover your funnels with Funnel Socks Air Cleaners.
The product is extremely handy. All you have to do is put it over the funnel.
It is free from air resistance and prevents almost completely dust &
dirt.
We machine funnel diameters smaller for free to make more clearances among the funnels for everyone who purchases both Funnel Socks Air Cleaner Set and Maruha Four Injection Units.
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