Jim Grant's Tech Tips
‘99 Ford Escort, Jerky Car
I recently bought a used ’99 Ford Escort with an auto transmission and 87K Miles. I showed it to a mechanic and he okayed it with a recommendation to change the battery which I did. He also asked me to ensure if the Time Belt was changed which I could not get proof except for a verbal one. Now many times while driving especially on uphill, the car gives jerks (as if the accelerator is missing the power on and off) and then it drives normally again after few seconds. Please suggest what do I do?
A timing belt will not cause the type of problem you’re describing. What you seem to be describing is an ignition type misfire. The most common cause for that condition that we see is a bad plug wire. More often than not in our shop it is the boot that goes over the spark plug that has a crack in it that allows the spark to jump to ground. When this occurs a sudden jerky feeling will occur. Usually the condition will be most pronounced in the range of 45 to 55 MPH with foot lightly on the gas pedal, just enough to maintain vehicle speed. As the condition worsens the range of speed and load that it occurs in will become greater. Because your vehicle has the second generation of On Broad Diagnostic (OBD II) it will also turn the check engine light on. If the problem becomes too pronounced, the check engine light will start blinking. The blinking light means the computer is in a total panic and really doesn’t want you driving the vehicle. Have your ignition system checked, it is likely there is some spark jumping the wrong air gap every now and then.