![]() ![]() The L12A, L13A and L15A use ( Japanese : i-DSI), or “intelligent Dual & Sequential Ignition”. Two different valvetrains are present on this engine series. The 1.5t engine is relatively new and still doesn't have many consumer reports about carbon deposition, but some other fresh Honda's DI engines started bringing problems related to carbon build-up at mileage about 50-60k miles. This process is exacerbated even more during short trips on a cold engine. The manufacturer knows about that problem and already introduced a solution that consists of several service campaigns that will include software updates, oil change, a new drain plug washer, and in some cases, the replacing of the climate control unit.Ĭarbon build-up on the backside of the intake valves is a problem of all engines with direct injection and no port injection. The problem with diluted oil has common symptoms: gas smells inside a cabin a higher-than-normal engine oil level check engine light comes on engine misfires. That all lead to the most reported problem for vehicles with Honda 1.5L turbo engine - a high or rising engine oil level due to oil/gas dilution problem. A direct fuel injection aggravates that problem because fuel, sprayed into the combustion chamber directly, sticks to the cylinder walls. A cold engine can develop condensation and excess fuel vapors that travel down into the crankcase and mix with the engine oil in the oil pan. This issue doesn't allow the engines to fully reach operating temperature on short trips. Many owners say it won't produce any heat until they start driving. The engine is so efficient and has minimal wasted heat. This feature is a disadvantage for a cold climate operation. ![]() The 1.5T engine doesn't warm up and produces enough heat while idling. Honda 1.5T L15B7 Engine Problems and Reliability The boost pressure of the Honda Accord is higher - 20.2 psi power output is 192 hp and 192 lb-ft. The boost pressure of the Honda CR-V is 18.5 psi it produces 190 hp and 179 lb-ft. More air needs more fuel - in this case, the Si engine was equipped with more productive fuel direct injectors.Įngines for the Accord and CR-V are based on the Si engine. The standard connecting rods were replaced by reinforced ones. Able to handle raised boost, this version has a lower compression ratio at 10.3 from 10.6 due to other pistons. The gain in power was achieved using more performance intake camshaft and higher boost pressure - 20.3 psi. The 1.5-liter turbo engine for the Honda Civic Si copies the European 1.5T VTEC Turbo engine specs. Only the 2.0L VTEC TURBO has i-VTEC (intelligent Variable Valve Timing and Lift Electronic Control) with the dual VTC. The manufacturer did not apply the true Honda's VTEC for the 1.5-liter turbo engine - there is no variable lift mechanism, only dual VT?. That means there is no mechanical connection between the acceleration pedal and the throttle valve. The engine speed is controlled by the electronic drive-by-wire throttle. After the intercooler, air goes into a plastic intake manifold. To reduce the temperature of intake air compressed and heated by the turbocharger, Honda's 1.5t engine uses a more common air-to-air intercooler. Boost pressure is 16.5 psi for a standard US Civic with a 1.5t engine and a 10.6:1 compression ratio. ![]() The small size turbo with electronic control minimizes a "turbo lag" effect and provides rapidly responds to acceleration. The L15B7 engine has a mono/single-scroll turbocharger MHI-TD03 with small-diameter turbines and electric wastegate. Exhaust gas cooling (by 100 degree C) prolongs the life of the turbocharger components and also helps the engine warm-up faster. The 1.5T engine also has a water-cooled exhaust manifold built into the cylinder-head - exhaust-port passages cast directly into the head. The cylinder head has high tumble intake ports (tumble ratio is 1.9) that strengthen intake airflow and promote efficient fuel combustion. Each multi-hole direct fuel injector is placed between two intake valves the spark plug is on top in the center of a combustion chamber. The intake and exhaust camshafts are equipped with actuators of the VTC. The head design includes four valves for each cylinder and DOHC (dual overhead cam) driven by the timing chain. Pistons are cooled by oil spray jets directed at the bottom of the piston. The manufacturers applied plateau honing (grinding process) for cylinder walls to reduce friction between pistons and cylinders even more. There are also new cavity-shaped pistons with an optimized skirt design to minimize vibration and friction and increase operating efficiency. The engine block is equipped with lightweight steel connecting rods (heat-forged for higher strength) to withstand high loads. The engine uses an aluminum open-deck cylinder block and aluminum cylinder head. Let's take a closer look at what makes the Honda 1.5l turbo engine so efficient and powerful. ![]()
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