Direct Injection is a little like a diesel engine in that it uses a high pressure (for gas), engine-driven fuel pump, with fuel sprayed directly in the cylinder. It is more like newer "common-rail" diesel injection, but at line pressures ~300 psi instead of ~20,000 psi (I think). Both have electric solenoid injectors. In both, the main advantage is the ability to schedule the spray. In diesels, they can avoid the sharp ping from a poppet valve opening (our cars), so don't need a pre-chamber to keep noise down in a car engine. In gas, they inject a lean charge, with a rich region at the spark plug to insure ignition.

My son bought a Chevy Cruze Eco a year ago, so I looked it up wondering if "too new, don't be GM's guinea pig like their Olds diesels" but found direct injection gas has been in production ~10 years and has no reliability issues. Still, I imagine repair parts will be much higher than MPFI when needed in 10 or 20 years.

I have worked on repairing this PITA technology when mitsubishi introduced it in the late 90s, the injectors are placed in the combustion chamber and squirt fuel at 1800 psi into the "ball" of air that the piston is rotating at tornado rating, The piston itself has a crescent on top of it to make this work.

The fuel injection was two step, once in the intake stroke to take advantage by "evaporating heat" as it is sprayed a little into the charge, then as the piston ascends the final injection is done at a few degrees before the coil is fired. This meant the engine could even operate at 20:1 fuel air ratio easily with no knock and the 1.8 litre engine could twist out the torque a 2.5 or 3.0 engine could. Its CR was very high too
Uptil now its pretty fantastic.

Now comes the ugly part. Due to the high CR and such special ignition charecteristics the engine produces soot like a diesel (no problem - we can use a diesel rated oil in there) - it also has an EGR the size of throttle blades in normal cars. so cleaning the massive intake manifold (the runners actually go through the valve cover as a straight shot into the cylinder) is required regularly.

Please read that it has a special shaped combustion chamber in the middle of the piston that makes the engine work, This high cr, high EGR and low speed running will coke it up and if the air tornado cannot happen the engine will balk and misfire.

It was required to decoke every 40,000 miles with walnut shells being blasted onto the piston face and vacuumed out. The injector faces and pintles can also coke up and clog. Operating at 1800 psi with a common rail type setup and being buried at the back of the head of the 4 cyl was a major PITA to remove and install and broke the bank to replace - If the HP pump on the head took a vacation - you were looking at costs usually reserved for servicing W140 S600 benz.

Technology has come ahead but has its own set of criteria to fulfill, its not like the old anvil engines of yesteryear. Aligning it with todays business model in USA regarding cars it would work as cars are disposed to be crushed every 5 years.

btw- these electric solenoid lifters... are these a modernised version of rhoads type lifters

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

DI engines are extremely efficient and reliable, and tmk not all that unreliable. Guess things have come a long way. My little hatchback has more hp and torque than muscle cars of a decade ago while returning 30-35 mpg. About time they came around!

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth