i've got the same problem with my '95 ex v6. the tach bounce doesn't start until after the engine warms up, but when driving, the engine misses periodically when the needle plummets. it occurs at idle also (needle bounce, not the missing). i changed out the icm (ignition control module), but no luck. i just read about another guy with the same problem, and he said that replacing the ignition coil will solve the problem. i've got one on order from rock-auto, and will post the results.

 

i forgot to mention, i tried a diagnostic on the obd at checker auto (they do it for free), but unfortunately it returned no error codes. also, i was told a computer will only pull codes if the check engine light is lit (i don't know how accurate that statements is, but it's what the checker guy said).

 

An internal problem in the ignition coil is the most likely cause of a jumping tach on a v6. It's a common problem.

 

what he said



could also be bad ignition module as well or voltage is not at properl levels (13..8-14.7)

 

i just got the ignition coil today, and installed it. sure enough, the tach has stopped bouncing, and the engine has stopped missing.