Focus Fanatics - View Single Post - anyone using premium gas ?
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Old 01-25-2013, 11:12 AM   #103
Ranx0r0x
Focus Rookie
 
Join Date: Jan 2013
Fan#: 109077
Location: Austin, TX
What I Drive: 2013, White, SE Hatch

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Stumbling...

dan50,

If you're getting stumbling with either 87 or 91 I'd say there's something wrong worth checking. I'm a new SE owner so don't know all the details of the engine operation of our vehicles.

In most new cars if the crank senses a difference in the amount of power from cylinder to cylinder the ECU changes operation. A common source of this problem is misfire. Plugs are a suspect and they are the cheapest to check and fix. A typical sign of plugs misfiring is stumbling at low RPM which smooths out at higher RPM.

Have you changed the plugs or wires recently? If so, did you switch from a colder to hotter or hotter to colder plug? Have you pulled the plugs to give them an eye?

Again, I'm a new owner of this vehicle/engine so I'm not up on its actual operation but this would be my first suspect.
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