Tech Tip of the month

We have recently received numerous reports of vehicles exhibiting trouble codes relating to lean conditions and mass air sensor or air temperature sensor codes. Manufacturers repair recommendations usually involve basic testing after which the daining of the fuel tank and replacement of the fuel and prolonged driving is the ultimate repair. Technicians find this an effective short term repair but receive little of no explanation. Not only can you provide an explanation, but you can also provide a much better and profitable solution.

First the root cause of the problem, High ethanol content in today's fuel allows it to absorb large amounts of water. When the fuel reaches it's saturation point it is prone for phase separation. Phase separation is a condition where the ethanol/water mixture actually separates from the gasoline. Ethanol is added to fuel for it's oxygenating properties. Extra oxygen is emitted when ethanol burns helping the exhaust emissions components (especially the Catalytic Converter) eliminate left over hydrocarbons. When the ehtanol mixture separates due to phase separation it drops to the bottom of the fuel tanks and is drawn into the fuel delivery system. Running on a high concentration of ethanol "tricks" the oxygen sensors into telling the computer that the engine is running to lean. The computer holds the injectors opened longer but that only adds ethanol which adds to the extra oxygen in the exhaust. A leand code is set. Eventually the computer may even set a code for an intake air temperature sensor or an air flow sensor as the computer is tricked into thinking that it must be improperly measuring the amount of air being brought in.

If the ethanol mixture at the bottom of the tank gets completely used up, the remaining fuel in the tank is octane deficient because thanol is an octane improver. The remaining fuel, after the ethanol is used up, may be 2 to 4 points lower in octane.

A proper repair can be completed with the following steps:

1) Drain 10 to 20 percent of the fuel into an appropriate container for proper disposal. (disconnect the fuel line at the filter and energize the pump)

2) Add Octi-Plus to remaining fuel to eliminate remaining water and restore Octane.

3) Perform Induction Service  to remove deposits formed from burning Ethanoll/Water mixture.

4) Road test vehicle