My car won’t start after I buy vanilla ice cream! HELP ME FIGURE OUT WHY.

The following story, once shared on PBS by the Car Talk  brothers Click and Clack, turned out to be an urban legend.  But I’ve rewritten the story to engage you in solving the puzzle and offering a valuable lesson in strategic thinking. The story supposedly involves “Fred” complaining to Ford Headquarters that his car won’t start whenever he buys vanilla ice cream.  Let’s hear from Fred:

“We have a family tradition of sending me out to buy ice cream after dinner each night.  We vote on what kind of ice cream we should have, then I drive two miles to the store to get it. But every time I buy vanilla ice-cream, my new Ford won’t start. If I get any other of ice cream, the car starts just fine.  Please explain why my car is allergic to vanilla ice cream?”

Ford headquarters asked him to carefully document his next four nights of buying ice cream.   The first night the family voted for vanilla ice cream, and sure enough, after he bought vanilla from the store and came back to the car, it wouldn’t start. The second night, he chose strawberry, and the car started promptly. The third night, chocolate was the choice and the car started fine. But the fourth night when he ordered vanilla, the car failed to start again.

What’s going on? Now, dear reader, think about it for a moment. What do you think the reason is?   What’s your working hypothesis (fancy word for “best guess”) as to why his car won’t start?  What additional information would you need to be sure?

Ford asked Fed to repeat his ice cream visits but to carefully capture data concerning time of day, type of gas used, outside temperature, time it takes to purchase, drive time back and forth, flavor selected, and whether the car started or not.

Scrunching the data provided a clue:  It always took Fred less time to buy vanilla then any other flavor.  With that additional insight, what’s your new working hypothesis about the root cause of the problem?

Ford then sent an engineer to the store to investigate further.  The engineer studied the store layout, noting that vanilla, being the most popular flavor, was placed in a separate case at the front of the store for quick pick up.

All the other flavors were kept in the back of the store at a different counter where it took considerably longer to get served. It was clear that now the issue was why the car wouldn’t start when buying ice cream took less time. Once time became the key variable– not the flavor of ice cream –  the solution became apparent: vapor lock.

Before cars had fuel injection, when a car was shut off, it needed time to cool down before it would restart.  This happened to his car every night but because Fred got vanilla more quickly, the engine was still too hot for the vapor lock to dissipate. But the extra time needed to get the fancy flavors allowed the engine to cool down sufficiently to start. Problem solved.

Lesson Learned: If your initial interpretation of the solution to a problem doesn’t make logical sense, search for alternative solutions. Refine and test your initial initial, dig deeper, get data.

Don’t confuse correlation with causation.  Just because buying vanilla correlated with a stalled car, that was not the causative factor. The rooster crowing in the morning doesn’t cause the sun to rise, though it may like to think it does.

The practical business application:  when your team is underperforming, it’s easy to blame the people. But as W. Edwards Deming reminded us long ago, look deeper at the system, the process, and the interfaces to see if they are working in sync. That’s likely where the problem is.

Be strategic and intelligent about discovering root causes.   And be assured that your car should start regardless of what ice-cream flavor you are hungry for.