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MECHANICALLY SPEAKING: More MacGyvering for the 21st Century

Two weeks ago I alluded to the fact that modern day automobiles can be MacGyvered the same as your thirty or forty year old automobiles. I suggested some additional tools are required. Well …. I lied. Just kidding.

The modern day tool kit requires smaller strong tools (we all know there is not a lot of space under the hood for working), a multimeter and a scan tool. Modern day repairs place considerably more emphasis on Ohm’s Law i.e. there is a lot of electricity/electronics involved.  They also require a little computerized intervention from that aforementioned scan tool.

Many people curse that little orange engine light I have written about many times, only because it seems like it is always on for something (another article for that subject). In reality that little orange light is your friend. You never had a little light to guide you through dark when you were working on your seventies’ muscle car.

Take a choke problem. Yes, you may remember the days of the carburetor and the manual choke which then begat the automatic choke which begat the electrically assisted automatic choke. Yes, those were better days…..not.

The choke was there to essentially mechanically reduce airflow and increase fuel flow when starting and running a cold engine. Cold engines need more fuel mixed with air to start and run.  As the engine warms up the fuel to air ratio must be reduced. With a manual choke the driver was in charge of balancing the air fuel mixture. The automatic choke took away that level of control. You old timers might equate it to my lamenting the replacement of manual transmissions with automatics.

So your seventies behemoth won’t start when it gets below zero. What did you do? Is the choke working? Open the hood, remove the air cleaner. Look at the flap on the top up the carburetor.  Is it closed? Does the choke open partially while the engine is cranking over? Is the engine over choked or under choked? Pry it open with a stick (seventies MacGyver). Try starting it. Will it start now? You may know the drill.

Step into the twenty first century. Out to start your fuel sipping compact car in the cold. It cranks over fine but won’t start. What to do? Connect up your scan tool. Read the codes. No codes. Check the sensor inputs to the engine computer. The modern day choke is much simpler. It is an electrical sensor that reads engine temperature directly from the coolant. Let’s see, the outside temperature is zero. My scan tool reports that the engine thinks it is minus thirty degrees (too much choke). Modern day MacGyver thinks. This vehicle has both an outside air temperature sensor and an engine coolant temperature sensor. The outside air temperature sensor reads zero as it should. Lift the hood. Find the coolant temperature sensor and disconnect it. The engine computer recognizes the missing information, turns on the check engine light and seeks the input of the second best choke information from the outside air temperature sensor. The engine starts on the first try.

Modern day MacGyver thinking gets you out of a jam. A choke is a choke be it the seventies version or the two thousands version.

In our pursuit of the non polluting automobile the engine performance control system has become fairly complex. With complexity has come redundancy. There are many backup strategies that keep an engine running. Sometimes the modern day MacGyver can force a backup strategy to get you home to your favorite mechanic.

E-mail: nutechauto@telus.net

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