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.
Importance of Service:
Problems can occur even with a slight buildup of deposits. Because the injector opening 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 vapor. Wear or deposits in the nozzle can create "streamers" of liquid fuel that vaporize and burn poorly. This, in turn, can cause hesitation, emissions and performance problems.
What May Happen if The Service is Not Performed:
Your fuel injectors may become 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 your engine to run lean and misfire, hesitate, or stall.