"The Tune-up of the Nineties," is what the literature claimed. It was said to clean enough carbon deposits and other contaminants from an engine to improve fuel economy, ease cold-starting, promote a smoother idle, quicker acceleration, and increase power. All this while lowering exhaust emissions. Pretty strong claims. Strong enough to arouse a good bit of skepticism from one who’s experienced any number of snake oil salesmen over the years. The product is usually some magic elixir which, when added to the gas tank, is supposed to miraculously cure whatever ails an engine. You know, do damn near everything but lower your cholesterol. Baloney. This one, however, wasn’t an additive. Called MotorVac, it was a procedure that sounded pretty logical, and importantly, the results of which could immediately be measured. That got our attention.
The fact is that even a one-year old car’s engine has accumulated carbon deposits, gum, varnishes, dirt and other contaminants that build up in the air intake, fuel delivery system, combustion chamber, and exhaust system. Yes, modern engine computers monitor and adjust for some of these changes, but in time, as these systems get further and further from original spec, inevitably, engine efficiency suffers. The way we usually experience this is subtle at first. Perhaps the car is a little harder to start when cold, or the idle is a bit lumpy, or the engine occasionally stalls, or gas mileage begins to edge downward. It is most likely a combination of the above. Left unaided, these symptoms get worse as the miles pile up. Acceleration suffers, power is down generally, and the engine is no longer smooth. A major contributor is incomplete combustion, which means along with the symptoms we notice, is one we frequently don’t - increased tailpipe emissions. An inefficient motor pumps significantly larger amounts of Hydrocarbons, Carbon Dioxide, and Carbon Monoxide out the tailpipe. In California, where Smog-Check II, a stringent new smog certification standard, has been adopted, some drivers have been unpleasantly surprised to find their year-old cars need substantial "fixing" in order to be certified.
As a matter of course, contaminated spark plugs are cleaned or replaced and engine computer sensors and functions checked to improve performance and bring tailpipe emissions in line. All well and good. But it stands to reason that maximum performance and fuel economy simply cannot be achieved if problem-causing sludge and deposits are in the fuel delivery system, not to mention the combustion chamber and exhaust system. These contaminants can be removed in two ways; by a time-consuming - and costly - teardown or by introducing some cleaning detergent. Here’s a rule of thumb. If it’s added to the gas tank, it’ll do a great job - of cleaning the gas tank. The trouble is, whatever sludge and deposits are dislodged from the tank usually just end up clogging the fuel delivery system, which can be thought of as a series of progressively finer filters on the way to the intake valves. Pack up any of those filters along the way and there are further problems.
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The fact is that even a one-year old car’s engine has accumulated carbon deposits, gum, varnishes, dirt and other contaminants that build up in the air intake, fuel delivery system, combustion chamber, and exhaust system. Yes, modern engine computers monitor and adjust for some of these changes, but in time, as these systems get further and further from original spec, inevitably, engine efficiency suffers. The way we usually experience this is subtle at first. Perhaps the car is a little harder to start when cold, or the idle is a bit lumpy, or the engine occasionally stalls, or gas mileage begins to edge downward. It is most likely a combination of the above. Left unaided, these symptoms get worse as the miles pile up. Acceleration suffers, power is down generally, and the engine is no longer smooth. A major contributor is incomplete combustion, which means along with the symptoms we notice, is one we frequently don’t - increased tailpipe emissions. An inefficient motor pumps significantly larger amounts of Hydrocarbons, Carbon Dioxide, and Carbon Monoxide out the tailpipe. In California, where Smog-Check II, a stringent new smog certification standard, has been adopted, some drivers have been unpleasantly surprised to find their year-old cars need substantial "fixing" in order to be certified.
As a matter of course, contaminated spark plugs are cleaned or replaced and engine computer sensors and functions checked to improve performance and bring tailpipe emissions in line. All well and good. But it stands to reason that maximum performance and fuel economy simply cannot be achieved if problem-causing sludge and deposits are in the fuel delivery system, not to mention the combustion chamber and exhaust system. These contaminants can be removed in two ways; by a time-consuming - and costly - teardown or by introducing some cleaning detergent. Here’s a rule of thumb. If it’s added to the gas tank, it’ll do a great job - of cleaning the gas tank. The trouble is, whatever sludge and deposits are dislodged from the tank usually just end up clogging the fuel delivery system, which can be thought of as a series of progressively finer filters on the way to the intake valves. Pack up any of those filters along the way and there are further problems.
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