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2008 Honda Civic 1.8L rough idle when the heater turns on
She says that when she's gets in her car and is idling, it's runs rough when she turns her heater on. Would like to know where to start, I've no access to Mitchell or anything like that but I do have scope and dvom and tools. Any tips would be great. Thanks
Does she notice that the engine runs rough at any other time? Like, driving down the road, or sitting at a stop in Drive?
To be honest, my first suspicion is a torn engine mount. Specifically, the big one at the front of the engine, or on the passenger side of the engine bay. They like to tear and cause all kinds of vibration to carry into the body of the car.
It may be that this mount is torn, and the symptom is more noticeable with the heater on because you're adding loads to the engine. If there's no codes and the scan data looks OK, I'd be looking at the mounts. The easiest way to check for this is to use a floor jack and a block of wood to gently lift the engine by the oil pan. If the front mount is torn, I'll be clearly visible when the engine is raised.
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