Fuel Injection Improves Power, Reduces Emissions

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: If you are driving a car that you bought in the last three years in the metros, then you are in all probability driving a fuel-injected car. From the humble Maruti 800 to the mighty Mercedes SL500, all are fuel injected.

While many people feel that fuel injection was introduced to meet government emission norms, equally important is the fact that fuel injection is an all-round better fuel delivery system. Fuel injection has no choke, but sprays atomised fuel directly into the engine. This eliminates most of the starting problems associated with carburettors.

Electronic fuel injection also integrates more easily with computerised engine control systems because the injectors are more easily controlled than a mechanical carburettor with electronic add-ons. Multipoint fuel injection (where each cylinder has its own injector) delivers a more evenly distributed mixture of air and fuel to each of the engine’s cylinders, which improves power and performance.

Sequential fuel injection (where the firing of each individual injector is controlled separately by the computer and timed to the engine’s firing sequence) improves power and reduces emissions. So there are some valid engineering reasons as well for using fuel injection.

The earliest fuel injection systems were mechanical and were more complex than carburettors. Consequently, they were expensive and their use was limited. Chevrolet introduced a Rochester mechanical fuel injection system way back in 1957. The Europeans, however, were the real leaders in fuel injection technology. Bosch offered an early electronic system on Volkswagen Squarebacks in the late 1960s and early 1970s.

By the early 1980s, almost all European automakers were using some type of Bosch multipoint fuel injection system. Engines with multipoint injection have a separate fuel injector for each cylinder, mounted in the intake manifold or head just above the intake port. Thus, a four-cylinder engine would have four injectors, a six-cylinder would have six injectors and a V8 would have eight injectors.

Multipoint injection systems are more expensive because of the added number of injectors. But having a separate injector for each cylinder makes a big difference in performance. Injecting fuel directly into the intake ports also eliminates the need to preheat the intake manifold since only air flows through the manifold.

This, in turn, provides more freedom for tuning the intake plumbing to produce maximum torque. It also eliminates the need to preheat the incoming air by forcing it to pass through a stove around the exhaust manifold. Due to our adulterated fuel, these injectors might get clogged leading to symptoms like knocking, low pick-up, bad fuel efficiency and increased emissions.

This is often attributed to fuel injectors becoming ‘dirty’. The term ‘dirty’ is actually a misnomer. Rarely are injectors clogged with dirt. Rather, they are usually clogged or restricted by a buildup of fuel varnish deposits. This reduces the amount of fuel that the injector sprays, which, in turn, may cause the engine to run lean and misfire, hesitate or stall. A fuel injector is nothing more than spray nozzle. The truth is any injector can clog.

Nobody’s injectors are immune to this kind of problem, but some are obviously better than others. Problems can occur even with a slight buildup of deposits. Because the injector orifice is so small, it doesn’t take much crud to restrict the flow of fuel or to disrupt the spray pattern. For good combustion, the injectors must produce a fine cone-shaped mist of fuel vapour. Wear or deposits in the nozzle can create ‘streamers’ of liquid fuel that vapourise and burn poorly.

This, in turn, can cause hesitation, emissions and performance problems. The cure for a set of clogged injectors is cleaning. If your injectors are clogged, they can be cleaned with pressurised solvent, or removed for off-car cleaning. There are also fuel tank additives that claim to clean clogged injectors, but the cleaning such products do is usually minimal. So save your money and put it towards a professional cleaning. On-car injector cleaning involves feeding solvent under pressure into the injector fuel rail or supply line.

The concentrated solvent passes through the injectors and loosens and washes away the accumulated varnish deposits. The results are usually good and make a noticeable difference in idle smoothness, emissions and fuel economy. I remember an incident some time ago, when a gentleman had imported a brand new Lexus LS400 in 1993, one of the early cars. Being a bit of a penny-wise-pound-foolish man, he would get his Lexus serviced at the local Maruti service station. In about 25,000 kilometres, he was complaining about rough idling and loss of power from his 4,000cc V8.

I knew the symptoms immediately and got all eight injectors removed and cleaned. Back then, most of the service facilities as we know today did not exist and we had to depend on the cleaning qualities of kerosene and spirit. The results were, however, dramatic and soon the car was back to its normal self. Today, the scenario is totally different. Besides having a number of after-market injector cleaners available, there are also premium fuels available like Speed, Power, Premium, etc. I thoroughly recommend using these new age fuels so that at least your Lexus keeps running like new!