Questions and Answers

Nissan Idle Problem

Q. I have a 1993 Nissan NX 2000, with a 4 cylinder, 2 liter engine, with manual transmission, 127,000 miles, fuel injected, no ABS, power steering, cruise control, rack and pinion steering. My problem is my car when it is warm and I am driving, I take it out of gear to come to a stop, as soon as I take my foot off the gas, the idle drops down to about 300 then goes back up to 1000 then drops back down to about 300 again, then it goes back up to 1000 and stays there. When the idle drops to 300 the light go really dim ad the heater goes really low. Do you know what the problem might be?

A. Three possibilities come to mind for this problem. There is an Idle Speed Control (ISC) motor that might be bad. A bad Throttle Position Sensor (TPS) or a bad idle dash pot. The idle dash pot slows the speed of the throttle plate down so it closes gradually and doesn't slam shut. Since this dash pot is not an electronic device, the computer can't keep an eye on it. Nissan has a tester called CONSULT which plugs right into the car and will determine quickly and easily which of these is causing the problem.