Yeah, this is strange! When I let up on the gas pedal, the speedo needle sort of jumps around and drops to zero. It remains at zero (it may bounce a bit) as long as the car is decelerating. The instant I push on the pedal, the needle returns to the proper speed reading. It is absolutely steady and working as expected as long as there is some acceleration. If cruising with very little throttle, the needle is steady but may show some instability. As the signal from the vehicle speed sensor is a sinusoidal AC signal, there should be no change in it's output dependant on whether it is speeding or slowing up, just a change in the frequency of the signal. From the FSM, it appears that the speed signal goes from the sensor to the speedo unit and then on to the ECU. This likely means the ECU is not a suspect. The only thing I can think of related to accel,decel is the throttle position sensor. The ony link would seem to be the ECU or a grounding problem.

Anyone had a similar problem?

 

I think it may be the speed sensor. The sensor is geared to the ring gear in the differential. When under accel load, the sensor operates properly. But, under the opposing load of decelleration, something in the broken sensor does not connect properly.

If you have a friend with a Max, try swapping sensors for aminute and see if that isolates the problem.

The TPS and ECU are not connected to the speedo in any way. The only signal it receives is from the speed sensor in the transmission.

 

Thanks MZMTG,
I think you are probably right. I had a speed sensor fail in my 1990 Accord but I don't recall if it had the accel/decel symptoms. My bro-in-law has a 95 as well so I will try a swap and see if that's it.