Two Killed by Carbon Monoxide Poisoning in Modified Ford Fiesta ST

The British driver had installed a modified exhaust system in a bid to boost performance.

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If you're looking to shave a few seconds off your car's quarter-mile time, there are a few straightforward routes you can take. You can tinker with the drivetrain setup, find a good ECU tune, add lightness—hell, even new tires alone can make an appreciable difference. But if you're going to open up the exhaust and mess around with the catalytic converter, the tragic deaths of two people in a modified Ford Fiesta ST in England shows the danger created when everything is put back together incorrectly.

20-year-old former Ford engineering apprentice Tom Putt and his friend Nikki Willis were sitting in the car outside Willis's house on the night of December 5, 2016. Neighbors say they heard the engine running around 4:30am, and their bodies were discovered later that morning. 

Police announced their findings today after working with Ford over the last few months to pin down the cause.

Putt apparently modified the Fiesta's exhaust system last year, removing the catalytic converter and adding vents in the hood. While local articles vaguely point to the missing cat as the reason the dangerous fumes were allowed to escape, a straight pipe on its own wouldn't cause this, and given Putt's experience it seems more likely there was a problem with the reassembly—possibly something as simple as missing or broken gasket, or a loose connection.

So leaking exhaust was allowed to build up under the hood since the car wasn't moving, eventually coming up through the added vents and entering the cabin through the fresh air intakes at the base of the windshield. It's also believed cold weather kept the gas concentrated around the front of the car. 

The report released today confirmed CO levels in the cabin were more than 1,000 times higher than the country's legal limit.

It's a tragic tale all around, and a sobering reminder of the inherent risks in messing around with complex machines. Check, check, and check your work again —your (or your loved one's) life could depend on it.