Chevrolet Cavalier, year 2000, 2400 engine, automatic, 115,000 miles.
Lately, when I am driving and my foot is on the gas pedal, suddenly the engine seems to hesitate briefly and the speedometer needle drops say from 60 to 40 for a fraction of a second, and then goes back up. The driving speed certainly does not decrease by anything like that. This does not occur when my foot is off the gas pedal.
I brought the car to an expert in fuel injection. He hooked up his computerized sensor and found nothing wrong.
What could the problem be?
There is a service bulletin out describing your problem. The service bulletin number is 00-06-04-044 dated October 2000. It describes a hesitation or stall condition on the 2000 Cavalier. The fuel modular strainer in the fuel tank should be checked out to see if it is clogged. It should be replaced if it is clogged.
If you have further problem let us know and we will look deeper into the electrical system.
The speedometer dropping erratically at the same time the hesitation occurred may be an indication that there's a computer-based issue causing the problem.
Did you notice if the Check Engine light flashed on at the same time?
The Vehicle Speed Sensor (VSS) sends a speed signal to the Powertrain Control Module (PCM), from there the PCM sends a speed signal to the speedometer by means of a serial data line.
It's possible that a circuit interruption (bad PCM, poor ground, poor connection) may have killed both spark or fuel, and the speed signal at the same time.
Just losing the VSS signal shouldn't cause a true hesitation, but may affect transmission operation.