My son noticed that for a couple of months before we took it in to our mechanic, at (106,300 M, 06-30-2006) that the car was having "hiccups" when the air conditioning was on, the automatic gear was on D,3,2 or R and while his foot was on the brake. The jerk-like movement didn't happen in P or N. I drove it, and found the car to be experiencing some kind of a forward jerking like motion when stopped at a red light or a stop sign. It would start the hiccup after having stopped for a few seconds, and have the jerking movement about every two or three seconds. When you took your foot off the brake and drove, everything was fine. Our mechanic didn't know what the problem was, but he replaced the belt tensioner bearing. That reduced the jerking motion a little, and was not happening as often.The problem came back a thousand miles later. He changed the spark plugs. It worked, for now. PS Should my mechanic changed the belt tension pulley as well at time?
My car has 110000 miles.
My car has an automatic transmission.
Hello, thanks for writing in. I’d be happy to provide my insight. Most of the time that this occurs, it is because of a slight misfire, or it is due to an engine mount problem. I usually start by checking the engine mounts. If those are fine then I install a computer scan tool to monitor the sensor readings and to see if there are fluctuations in engine rpm. This can be caused be a fuel injector that is a little dirty or an ignition coil that is failing. Both are common problems. I would wait to change the belt tensioner pulley until it is confirmed that that is a problem.
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