Among the direct-injection diesel engines of the VAG concern with a volume of 1.9 liters were atmospheric variants. They are designated by the abbreviation SDI – from the German Saugdiesel Direkt Einspritzung (atmospheric diesel and direct injection).
The first SDI appeared at the end of 1995 – it was put on VW Caddy (1.9 SDI (AEY)). Then different variants of SDI engines with power from 64 to 68 hp appeared on Fox, Polo, Golf 4, Jetta, as well as on Skoda Fabia, Octavia and Seat. For Europe, these engines were produced until 2006, and, for example, in Argentina they were also found on cars produced before the beginning of 2010.
Structurally, these diesels differ in attachments and its location. They are also close to turbodiesel 1.9 TDI, but, of course, they are simpler due to the lack of a turbine, intercooler, sensors and control valves. There is no mass fuel consumption sensor on SDI motors either.
For fuel injection on 1.9 SDI engines is responsible Bosch VP37 fuel injector with electronic control. The gas pedal on all these engines is electronic.
VW AEY 1.9 SDI engine specifications
| Parameter | Characteristics |
|---|---|
| Exact volume | 1896 cm³ |
| Power system | Direct injection |
| Engine power | 64 hp |
| Torque | 125 Nm |
| Cylinder block | Cast iron, R4 |
| Cylinder head | Aluminum, 8 valves |
| Cylinder diameter | 79.5 mm |
| Piston stroke | 95.5 mm |
| Compression ratio | 19.5 |
| Engine Features | SOHC |
| Hydrocompensators | Yes |
| Transmission timing | Belt drive |
| Fasoregulator | No |
| Turbocharger | No |
| Oil | 4.3 liters 5W-40 |
| Fuel type | Diesel |
| Environmental class | Euro 2 |
| Example service life | 500,000 km |
Is the 1.9 SDI engine reliable?
Direct-injection diesels 1.9 are quite reliable, well diagnosed, very many parameters of their work are perfectly readable by diagnostic equipment. It cannot be said that SDI variants are much more reliable than TDI. Although yes, the absence of a turbine simplifies a lot in operation. At the same time, many criticize SDI for a very modest power.
Engine cushions
Often owners of cars with a 1.9 SDI engine are concerned about strong vibrations of the motor when working. In most cases, it is not the engine that is to blame, but the destroyed cushions of its supports. And the cushions may be intact. They must be replaced with the original or an expensive analog. On cheap substitutes, the engine 1.9 SDI can continue to vibrate strongly.
Oil leaks
Often on the 1.9 SDI engine there are oil leaks on the valve cover, heat exchanger. If the gasket for the heat exchanger is sold separately, then the valve cover gasket is original together with it. You cannot buy it separately, and a new valve cover costs more than $100. There are already non-original gaskets on sale, but they don’t always fit. It remains the installation of the cover on the sealant or buying a good cover from the dismantler.
Starter engine 1.9 SDI
“Weary” starter engine 1.9 SDI (and 1.9 TDI) can also be the culprit of a bad start of the engine on hot. It always seems that the starter turns perfectly, but the engine does not start. But the thing is that the ECU of this engine does not give a command to fuel injection until the crankshaft speed at antifreeze temperature above 70° does not reach 250 rpm. The battery and all power wiring should be fine too.
Coolant temperature sensor
The antifreeze temperature sensor can also be the cause of poor starting of the 1.9 SDI engine. The sensor is notorious for not lasting very long. And it does not fail, but gives incorrect data about the temperature of antifreeze. Accordingly, the ECU sets inappropriate injection parameters for starting a cold engine, from which it starts for a long time or does not start at all. Because of the antifreeze temperature sensor, the motor 1.9 SDI starts badly both cold and hot. To check it, you can remove its chip – after that the engine is likely to start, because the ECU will set the injection parameters as at -30°.
HPVD
The Bosch VP37 high-pressure fuel pump is quite reliable and unpretentious, it serves properly for several hundred thousand kilometers. When the plunger pair is worn out, floating idle speed is observed. Also, the revolutions can float due to contamination of the inductive sensor of the rotor position of the fuel injector. In this case, cleaning the mechanism and the rotor surface helps.
Also because of a worn plunger, the motor stops starting on hot. To diagnose the hot pump is poured cold water – cooled – and start the engine. If it starts – the fuel pump is to be reassembled.
Though usually it doesn’t come to reassembly of this fuel injector, but it may require adjustment of fuel supply and injection advance angle. If there are doubts about the serviceability of the fuel injector, you need to make sure that it is supplied with fuel. If it is supplied, it is necessary to check the fuel pressure in the return – it should be about 1 bar when cranking the starter. Usually, it is found that there is a blockage, and the fuel injector needs to be pumped.
MUKT
The fuel quantity control mechanism (FQCM) is located on the pump itself. If you loosen the four bolts of its mounting, you can adjust the cycle feed. This is done by moving the mechanism longitudinally by a fraction of a millimeter. Moving the ICCT towards the tubes increases the feed rate. Such adjustment should be done with the diagnostic software connected to the control unit (on a laptop) and accurately set the actual feed parameters – they must coincide with the required ones. All these parameters are immediately visible in the software. The cycle feed can also be set using the diagnostic software.
Adjustment of the injection advance angle is performed by moving the pump. For this purpose, the bolts of the fuel injector mounting are loosened, after which it must be moved slightly. For example, in order to change the RPM towards advance (to make it earlier), it is necessary to move the fuel injection pump towards the engine block. Again, all injection parameters – required and actual – can be seen in real time when a laptop with the appropriate software is connected.
There is a rubber gasket around the perimeter of the MCT cover. It keeps fuel from leaking even when the cap is loosened for adjustment. If fuel leaks through it, the cap must be removed and the gasket replaced.
Injectors
Among the four mechanical injectors of the 1.9 SDI engine, there is one special one with a needle lift sensor, by which the injection delay is taken into account. If it fails, the engine goes into emergency mode. Diagnostics clearly indicates a malfunction of the control injector.
On repairing the injectors – they need to replace the atomizers, which over time begin to pour fuel.
EGR valve
The EGR valve is controlled by vacuum and the corresponding valve N18. Accordingly, EGR valve malfunctions can occur due to vacuum leaks in the tubes or fittings, as well as a malfunction of the control electro-vacuum valve. In most cases, when the EGR valve malfunctions, there are short-term power dips or jerks in a certain rpm range.
The 1.9 SDI engine oil burn
The 1.9 SDI engine can be frustrating when the oil level drops. Sometimes the cause is oil leaks on some seals. But there are also known cases of oil consumption due to oil rings. It is worth measuring the compression in the cylinders before the repair.
When replacing piston rings, it is not superfluous to measure the diameter of the cylinders – it is possible that ellipticity will be detected. In this case, replacing the piston rings will not help. You will have to either have the block sharpened or buy a contract block.