My 95 Accord EX/V6 with auto trans has a strange intermittent problem with the tach needle bouncing or not working. Sometimes at road speed after apparent torque converter lockup, if the tach starts bouncing crazily the car will have a surge effect as if shifting between gears.I found a wiring diagram that shows a signal line coming off of ignition coil that goes to the tach and trans control module. It makes sense to me that this signal is failing intermittently. The surging effect is not apparent if I keep the gear selector in 3 and not 4.I would have to say that the coil itself works ok because when stopped and in neutral, even if the tach is crazy, I can rev the engine without any faltering. Wiring diagram shows some "circuitry" sealed inside the coil. I am thinking this is the problem..coil works, but not providing constant signal to tach and TSM.Any ideas or diag hints.Dealer was no help.

 

you have a bad ignition coil its on the left front of the engine under the distributor! just replaced one today on a customers car

 

Just wanted to bump this old thread because the OP described exactly the problem I had last week. I pulled the coil and found the back of it was all cracked; replaced it and everything is fine. When removing the coil there are 3 spacer washers between the coil and the bracket. Don't lose them and make sure to put them back when putting the new coil on. Without them you could potentially crack the body of the coil when tightening the bolts.

Thanks Honda-Tech community for the useful information.