Questions and Answers

Ford Explorer Torque Converter Clutch Q. Vince, I recently had a transmission rebuilt for a 1992 Ford Explorer. It's an A4LD. Here's my problem: While driving at highway speeds, usually in excess of 60 mph, the torque converter unlocks, and the engine rpm jumps up about 500 or 600 rpm. If I speed up to about 68 to 70, it will engage, but if I slow down to around 66 to 64, it will again disengage. It does fine at all other speed ranges.

The proprietor of the transmission shop said I have an electrical "glitch" somewhere, that causes the converter to unlock. Start with fuel system cleaner, as the idle rpm, and curb idle seemed to fluctuate about 150 to 200 rpm.

He said possibly TPS, but don't just start changing out parts randomly. Can you give me your best shot at this?? I have run several tanks of fuel, with cleaner, and have less fluctuation at idle speeds.

He did demonstrate how touching the brake pedal, with converter engaged causes it to unlock, explaining that several things are "computed" to cause engagement.

Thank you for your time, and your web site.
Claude

A. It is true there are several things computed to cause engagement of the torque converter clutch. In your case and situation I would first check the vehicle speed sensor. A visual inspection of the tone ring to ensure there is no damage, and I would give the sensor itself a good cleaning

If the sensor itself appears to be in good adjustment and the wiring is intact. I would then disconnect the negative battery terminal for 1 minute, depress the brake pedal for 5 seconds, reconnect battery and test drive.