Nissan Qashqai LPG - half-priced power
When launched in 2007 (debut in Paris in 2006), the Nissan Qashqai was a market niche in its own right. By "melting” together a compact and a small SUV, the Japanese firm created a successor to the Almera and the Terrano II in just one vehicle, thus creating a new category altogether. The effect? A compact, but rugged-looking new model, offering a higher driving position and some off-road ability (not too far away from asphalt, though). Well-known flavours were blended into a cocktail where no ingredient dominates the other one. In other words, the Qashqai is a 100% crossover – the sum is different from the parts included.
Under the bonnet there can be one of the petrol engines – 1,6 l (117 HP) or 2,0 l (140 HP) or any of the three dCi diesels – 1,5 l (110 HP), 1,6 l (130 HP) or 2,0 (150 HP). Since only petrol motors can be easily and effectively converted to run on LPG, we focus our interest on them exclusively. Even though these engines have sadly been "cost optimised” and are generally regarded as sensitive in terms of valves and valve seats durability, opinions circulating the Web show that Qashqais do not fear autogas adaptations. Still, investing a little more to get a valve saver kit, protecting valves and seats from premature wear, might be a good idea.
The test car
The Qashqai we were given to drive for a while had the more powerful petrol powerplant up front – the 2-litre four-pot. As for power, it was supposed to have 140 HP, but a dyno test showed something different. We will come to that later on. The car belongs to an autogas systems producer from Radom – Auto-Gaz Centrum – so naturally it was converted with the company's top product, the Zenit Pro. The Qashqai was converted to show how things should be done and serve as a prop during technical trainings held for installers cooperating with Auto-Gaz Centrum.
Zenit Pro – a controller for sequential injection autogas systems – may be used with the most technologically advanced petrol engines. Depending od version, it fits 4-, 6- and 8-cylinder motors.
The ECU used for the conversion of the test Qashqai had an OBD module, which utilises on-board diagnostics system signals to adjust the composition of the gas-air mixture in real time so that OBD corrections remain in the same range as when driving on petrol. Zenit Pro supports all data transmission protocols available – both analogue and digital ones, among them ISO, KWP 2000 and CAN.
The ECU's circuit board has four layers and the efficient processor, together with high-capacity memory, ensure high-speed data processing. Gas injectors are controlled with high electric efficiency (12 A) semiconductor elements equipped with overload and thermal protection, as well as built-in self-diagnostics. As for the ECU, electromechanical conductors have been eliminated from the construction. Instead, semiconductors have been used for controlling electrovalves and cutting off petrol injectors in the emulator circuit. Also these semiconductors are protected against electrical and thermal overload and have their own diagnostics systems.
The diagnostic connector is quite interesting. Normally, in everyday use, it is utilised for connecting the cabin petrol-to-gas switch. At the time of occasional maintenance, the connector is used for plugging in a diagnostic interface. Switching over is then available as a software option. For connecting a computer into the ECU, a specialised USB key is required. This eliminates the risk of unauthorised change of parameters attempts. Every time a diagnostic interface is plugged in, a trace containing the date and hour, as well as the computer's unique number, is left in the ECU. On top of that, access may be limited by setting up a password.
The ECU's cutting-edge technology made it possible to implement several interesting options, among them "fuel overlapping”. This means fine-tuning of the petrol-to-gas switchover in such a manner that the precise moment is undetectable for the driver. Also, the Zenit Pro allows partial petrol injections while the engine is running on gas, which is helpful for fine-tuning certain engines, particularly in high RPM ranges, so that they have the same parameters as when running purely on petrol.
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