Just learned how much a single spark plug gap can change fuel burn

I was reading an old service manual for a 2002 Honda Civic and it said a gap off by just 0.010 inches can drop fuel economy by almost 2 mpg on that model. Found it while looking up a misfire code for a customer's car. Always knew gap mattered, but seeing the exact number for a common engine was a real eye-opener. Makes you double-check every set you put in now. Has anyone else come across a small spec that had a bigger impact than you expected?

2 comments

2 Comments

cameron7631mo ago

That's a huge drop for such a tiny measurement. It really shows how precise these systems are. Makes you respect the factory specs a lot more.

henry1011mo ago

Always check your own work first.