In 2002, VAG introduced its first 3-cylinder gasoline engines with a displacement of 1.2 liters. Their production continued until about 2015. In the model range there are engines with both 2 and 4 valves per cylinder. The weakest copy develops 54 hp, and the most powerful – 70 hp.
Engines 1.2 HTP with three cylinders (indices AWY, AZQ, BME, BMD, BBM, BZG, CEVA, CHFA, CGPA) have the same cylinder blocks and cylinder heads (they come with 2- and 4-valves per cylinder). The attachments on these engines are different.
The marketing acronym HTP stands for High Torque Perfomance, which stands for High Torque Perfomance engine. These 1.2-liter motors develop between 106 and 112 hp at 3,000 Nm. In principle, a 3-cylinder engine is enough for a small car like the Fabia. Although, according to some owners, this motor is not so economical and consumes about the same amount of fuel as its 1.4-cylinder counterpart.
Spark plugs and coils
The coils and spark plugs on the 1.2 HTP engine are not very durable. Due to frequent idling and sluggish driving in traffic jams, the spark plugs are covered with deposits. As a result, ignition misses occur. Faulty spark plugs create conditions for ignition coil failure.
Ignition problems are indicated by corresponding errors. Plus, the control unit simply disconnects the corresponding cylinder, for which too many ignition skips are registered. Then the engine loses a lot of power and vibrates. After restarting the engine, the problem cylinder works for some time before another disconnection.
You can check the performance of the coils on a running engine: if the engine trots at idle and its behavior does not change after disconnecting the coil connector, it is the coil that is defective. If the engine starts to run harder, the coil is faulty. On the cylinder with a faulty coil it is very desirable to disconnect the injector, if it is necessary to drive to the service station on your own.
Injectors
The injectors of the engine 1.2 HTP are sensitive to the quality of fuel. Often the cause of the engine 1.2 HTP trojan is the clogging of one of the injectors. Fuel is not injected and ignition misses occur.
The injector can be “revived” by ultrasonic cleaning, and it is better to clean the whole set at once.
Antifreeze temperature sensor
Failure of the coolant temperature sensor can be the reason that the engine 1.2 HTP starts badly on hot. If through the problem is repeated, and the engine starts normally in the morning or after cooling down, then almost certainly the breakdown can be eliminated by replacing the antifreeze temperature sensor.
Throttle valve
The need to clean the throttle valve is often indicated by a poor mixture error, cases of engine stalling when idling, as well as “dulling” of the engine in response to the gas. After removal and installation, the choke must be adapted. This can be done either with proprietary software or without it – by manipulating the key and ignition switch.
VAC valve
The 1.2 HTP engine uses a fairly standard crankcase ventilation valve. If something happens to it, it is the destruction of the diaphragm. In this case, the engine starts to run rough at idle, and it “shakes” even more when the oil filler plug is removed. And, of course, excessive gas pressure begins to escape through the neck. If you do not notice the problems with the VKG valve in time, there will be ignition misses and oil consumption will increase significantly. The valve is relatively inexpensive, there is also a repair option with the installation of a non-original diaphragm.
However, it was on the 1.2 engine with index BMD initially used a defective valve, because of which the ventilation was broken, and valve gases squeezed out oil through the dipstick. Surviving engines have been replaced under warranty with a serviceable valve (03D 103 765A).
Transmission timing chain failure
VAG 3-cylinder engines are still notorious for chain overshoot. The 6-valve variants can survive a small jump of 1-2 teeth – the pistons and valves will not meet. But the 12-valve version of the engine is scrapped in any case because of the jump.
On this engine, the chain is strongly stretched and can jump already at a mileage of 50,000 km.
This mishap happens both on early 1.2 HTP engines and on the latest ones. It is actually impossible to check chain stretching when buying a car or engine without opening the timing cover. You can and should listen to the engine 1.2 HTP in the first seconds after cold start. Extraneous noise, clanking and knocking will indicate chain stretching. In general, it is better to change the chain preventively: when you buy a 1.2 HTP engine or when you buy a car with this engine. Further – at an interval of about 70 000 km. There is no official regulation of chain replacement on the 1.2 HTP engine.
And when operating a car with a 1.2 HTP engine, we advise you never to leave the car parked in gear, especially on a backward slope. The point is that here too there is no backstop in the hydraulic tensioner, and therefore the risk of chain “sagging” when the car is parked in gear is very high.
To prolong the service life of the engine 1.2 HTP will help to change the oil every 7-8 thousand kilometers. The full volume of oil in this motor is 2.8 liters, so it loses its best properties rather quickly. When replacing, 2.5 liters are placed, so the oil service is inexpensive.
Chain tensioner
Engineers, who created the engine 1.2 HTP, seriously miscalculated with the guide bars and the hydraulic chain tensioner. It is not known how many motors died because of this. But it is known that the engineers tried to correct their mistakes.
The factory-recognized problem with the 1.2 HTP engine, which they addressed in the early years after production began, had to do with extraneous sounds from the timing chain in the first few seconds after starting the motor. If a knocking or clanking sound was heard, the source was the hydraulic tensioner. It was either the tensioner piston or the tensioner bar hitting the housing.
In 2003 and 2005, respectively, improved tensioner guide bars and hydraulic tensioners were released, as well as repair kits with improved parts. Generally speaking, the hydraulic tensioner and guides are included in timing chain kits along with the gears.
HBTs and valve burnout
Many 1.2 HTP engines suffered from poor quality gasoline during their youth (i.e., from 2002 to 2010). We have already talked about the failure of plugs, coils and injectors. But the most unpleasant cause of this motor was a drop in compression. In most cases, the valves on one of the cylinders stopped seating normally.
Because of low-grade gasoline, the catalytic converter was destroyed and clogged – as a result, there were conditions for overheating and burning of exhaust valves. High temperatures and gas pressure from the exhaust manifold also caused wear on the valve stems and valve guides. Usually one of the cylinders suffers because of the valves and problems in the cylinder head. With any manifestations of engine 1.2 HTP trojan, experts advise to immediately check the compression.
Pistons
Usually, the 1.2 HTP engine does not suffer from piston ring seizure. But ring seizure and the accompanying decrease in compression can occur when using low-quality or counterfeit oil.
Liners
The 1.2 HTP engine block is cast from an aluminum alloy, with cast iron liners placed in the block during casting. The block is split in two along the crankshaft axis. Repair instructions forbid removing the lower part of the cylinder block, as it is fraught with deformation of the bed of the main liners. Therefore, for the 1.2 HTP engine, the factory does not offer original main liners of nominal size. However, it is possible to find good repair size liners on sale. And yes, practice shows that the block of this motor can be hollowed out, overhauled and reassembled. There is no deformation of the bed.
Balancer shaft
To balance the moments of inertia of a 3-cylinder engine, a balancer shaft with a spring chain tensioner is used. If for any reason the 1.2 HTP engine stalls, it is possible that the balancer weight will move slightly off its shaft. It will be impossible to get it back to its nominal position. It will have to be replaced.