1995 Ls400 - Suttle Misfire?

[sonyman]

For a few months now, my LS400 has had a misfire between 45-60 MPH. Applying throttle pressure only makes it worse. It makes its presence known as subtle vibration. I changed the spark plugs, wires, caps and rotors and gained some power, but it didn't fix the problem. The last time I took my car in to the shop my mechanic told me it was a misfire, but he doesn't recall making this diagnosis and now doesn't seem to know the cause of the problem. Another reason why he thought it was a misfire is because one time I started the car and the engine was violently shaking for 20-30 seconds before it smoothed out. If it's not a misfire, then what is it, and what can I do to fix it?

[sonyman]

After driving the car some today, I have found that the mis is actually still present at higher speeds, but barely detectable. For all I know, it's the same way at lower speeds but too suttle to notice.

[etex]

Try a search on "ignition coils" and see if you find some similarities.

[sonyman]

Try a search on "ignition coils" and see if you find some similarities.

I thought it might be a coil, but my mechanic says that typically, if a coil goes bad, it doesn't work. Period. Meaning, I'd be running on 4 cylinders. What's your take?

[dcfish]

Try a search on "ignition coils" and see if you find some similarities.

I thought it might be a coil, but my mechanic says that typically, if a coil goes bad, it doesn't work. Period. Meaning, I'd be running on 4 cylinders. What's your take?

Intermittent fuel injector ? Have them tested.

[LScott400]

I thought it might be a coil, but my mechanic says that typically, if a coil goes bad, it doesn't work. Period. Meaning, I'd be running on 4 cylinders. What's your take?

Here is a Link that explains coils and makes the point that a basic resistance test may test good while the coil may start to fail under load.