A good chunk of the market is dominated by Toyota, and the good chunk of Toyotas sold come equipped with a modern direct inject turbo diesel engine. It's this huge market that prompted Dastek to develop a D4D engine specific diesel injector driver that delivers more power than Unichip can alone. So how does it work?

2kd engine

First of a primer on how the modern turbo diesel works and how it makes power.

The diesel engine is a compression iginited internal combustion engine, which simply means that the air fuel mixture goes bang when you squeeze it enough, unlike a gasoline engine whch needs a sparkplug to make the bang. Diesel engines inject the fuel directly into the combustion chamber and it ignites almost immediately once in. The more diesel you can inject into the engine, the bigger the bang and the more power you'll make. But simply throwing more fuel at a diesel engine doesn't immediately make power, but it could be a cause of excessive black smoke, which is always bad. When the injection starts and how long the fuel is injected is also very crucial in making power.

Let's the the typical 2.5L D4D Toyota engine that's found in everything from the Innova to the Hiace. In stock form, the engine's ECU relies on the mass air flow sensor to determine how much air is going into the engine, which then directs the injectors to open and close a certain amount at every rpm point. The amount of squirt each injector gives is dependent on the fuel pressure which is in the fuel rail, and this rail pressure is monitored by a fuel rail pressure sensor that checks if it's within the ECUs correct parameters, which adjusts the fuel pump according to how high or how low this sensor is reading

So how do we get the ECU to inject more fuel to make more power? Most of the plug and and play diesel boxes plug into the fuel rail pressure sensor. This sensor has an operating range of 0-5V, what the diesel boxes do is "lower" actual volatge coming from the sensor, whcih cause the ECU to think "Hey fuel opressure is low, must pump more fuel" thereby raising fuel pressure, giving more fuel per injector squirt. All diesel boxes from DP chip, to DTP to Racechip use this method to gain more power.

How then is Unichip different?

While Unichip does also tap and alter the fuel rail pressure sensor signal, it also gets input from the vehicle's mass air flow sensor and throttle position. Remember when the fuel is injected is just as important as how much fuel is injected? Unichip was the ability to advance the injection cycle, which means it can inject fuel earlier and longer. Diesel boxes simply provide a blanket value for the whole rpm range, which is why they can never optimze the whole rpm band, you either set it for early power, mid range or top end, but never all 3. Unichip adjust fuelling every 400rpm increments with a range of +/- 50%, this level of precision can never be matched by any diesel chip, no matter who makes it. Also of note, the rail pressure has a certain operating range, too much or too little will cause a check engine light. There is a maximum limit on the adjustment you can do just based on the rail pressure sensor.

We now have to look elsewhere to be able to add more fuel for more power. And the injectors are the next step.

Think of the fuel injector like the head of a garden hose with spray handle. Fuel pressure is the analogous to the water pressure inside the hose, which is attached to the end of the faucet. This is analogous to the fuel pressure, turn the knob for more, and close it for less. The spray handle is the fuel injector. How much water is squirted out is determined by how long you hold the sprayer open. This is what the Unichip D4D driver does, it lengthens the time the injector is open, thereby delivering more fuel into the combustion chamber. Longer squirt means more power.
garden hose

More fuel pressure and a longer injector open time equals more fuel per squirt, which equals more power.

The D4D injector driver was developed specifically for the Toyota D Series diesel engines which include the 1KD and 2KD found in the Fortuner, Innova and Hilux, and the 1VD found in the Land Cruiser 200. Its also compatible with the newly released 2.8L and 2.4L GD engines in the 2016 Fortuner, Innova and Hilux.

Here's the dyno chart of a Toyota Innova 2.5L 2KD engine. The specifications for this engine is 101hp and 192 ft-lbs torque according to the official brochure from Toyota. Note these are crank HP figures. Putting the Innova on the dyno shows us actual wheel HP is little under 70whp.

innova d4d stock

Blue Line - 69whp Stock Power
Purple Line - 85whp Unichip Tuned
Orange line - 98whp Unichip D4D added

With Unichip tuning alone, we managed to increase the power to 85whp. Adding the D4D driver and the power jumps to almost 100whp. And this is on a completely stock vehicle.

innova modified dyno

Now here's what happens when we have other modficiations such as front mount intercooler and full 3" exhaust installed.

Blue Line - 90whp with K&N filter, front mount intercooler, 3" full exhaust
Purple Line - 117whp Unichip Tuned
Orange line - 130whp Unichip D4D added

That's almost double the orignial power level of the vehicle! But will all these modifications break the engine you ask? The short answer is no. The reason being is that diesel engines are extermely overbuilt from the factory, way above the rated operating power level. Plus Toyota released a newer intercooled variant of the 2KD engine that makes 140hp with the same block and internals, which means the engine easily handled the 40hp increase with no changes to any of the internal components. In the case of the IMV family of vehicles, the Unichip and the D4D are installed behind the passenger glove compartment, which is where the ECU is located.

d4d driver innova

The D4D module can also be installed on the the V8 turbodiesel found in the Land Cruiser 200. We will be needing 2 of them since each module controls 4 injectors. The 40hp power gain is great but the real hero of the story is the torque! 130 ft-lbs gain over stock!

d4d lc200 install

l200 d4d dyno

Red Broken -  203whp 444 ft-lbs stock
Red Dotted - 229whp 530 ft-lbs Unichip Tuned
Blue Line - 240whp 570 ft-lbs Unichip D4D added