2000 Toyota Avalon misfire issue

Hello all,

I’ve been having issues with my 2000 Toyota Avalon for the past few days. After troubleshooting with my mechanic this morning, we discovered that the front three ignition coils (when looking at the car from the front bumper) do not function when the car idles. However, they seem to work perfectly once the RPM increases past about 2500. I bought some new ignition coils to replace the originals, but no joy with those. The idle is still very rough and one can feel the misfire any time the engine is not revving higher than 2500 RPM. During our tests, we also found that the original coils do not produce a spark when the spark plugs are inserted. I did the same test with the new coils and had the same result, although the middle plug sparked briefly. The fuse for the ignition coils has been checked (it’s fine) so I’m fresh out of ideas. I know it must be electrical but was wondering where exactly the problem lies? I would greatly appreciate any and all feedback.


Since no one has responded to a very weird problem, I’ll start by asking a few questions.

Any codes present?

How many miles on the car?

Just how many miles do those plugs have on them?

Offhand, I’m leaning toward a misdiagnosis of the coil problem.

I suspect the signals from the crank and cam position sensors are weak at low rpms.
This is something that can be tested. Don’t just throw parts at it.

Thanks for the replies. I believe it was a “12 code” that was causing the check engine light, hence the conclusion of the ignition coils being faulty. The readout was saying it was a random misfire. The car is high mileage, about 244k and the plugs actually needed to be changed and will be as soon as it is possible. As far as the signals from the different sensors, how exactly does one go about getting this tested? Is this something that any accomplished mechanic should be able to do?