CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Car bogging down

My 2009 PT Cruiser has about 38800 miles on it and in the last two weeks, only when I turn my air on, it has started bogging down and missing when driving or idling…any ideas what would cause this??? Changed gas and that didn’t help

Is the check engine light on?

At that age & mileage there really shouldn’t be anything causing it - which just means that anything related to how the engine runs could be doing it. The basics are fuel, air & spark.

If you have no check engine light, then the first thing I would do would be basic maintenance things. I would do those things because they a) do not involve a lot of time or money and b) are good to do no matter what. My basic list would include new fuel and air filters; an inspection of spark plugs & wires; cleaning of the throttle body, idle air control valve and mass airflow sensor (if so equipped). I don’t know the recommended plug replacement interval but if it was even close I’d just replace the plugs.

I would do all of those things and if it didn’t help I’d feel fine about it anyway since all of that is good basic maintenance. But I would then be thinking about getting it on a high-end scantool. The AC puts a hefty load on the engine and the computer is supposed to adjust for the load. Perhaps there is a communication problem in there.

Plugs are due at 30k. That’s a good place to start.