Runs rough after heavy rain

[brillo_76]

T4R2014 is correct +1. You start noticing misfires etc only when raining its always a toyota coils or spark plug wires. In time, the coils break down/or plug wires and will short when raining causing this issue. Was a lot more common in the older toyotas models but with these being the age they are. Its showing up on occasion. Seems to be less common then the 80s and 90s though.

 

[T4R2014]

T4R2014 is correct +1. You start noticing misfires etc only when raining its always a toyota coils or spark plug wires. In time, the coils break down/or plug wires and will short when raining causing this issue. Was a lot more common in the older toyotas models but with these being the age they are. Its showing up on occasion. Seems to be less common then the 80s and 90s though.

TBH, I replaced all my coils thinking it would fix my cold start hesitation. It didn't, but it gave me a pretty noticeable power bump.

 

[brillo_76]

TBH, I replaced all my coils thinking it would fix my cold start hesitation. It didn't, but it gave me a pretty noticeable power bump.

I only change them when i have an issue. In the 5VZ-FE Waste spark systems. They really seem to be fairly durable. The older 22Rs and 90s 4 cylinders will more fleaky on coils and wires.

 

[Previologist]

This is a not infrequent problem on Previas, which have the distributor and coil under the vehicle. Dielectric grease usually solves it.

 

[desertegal7]

Fuel pump harness / terminal/ plug

hello i had the same issue, i did everything but couldn't figure out what gets wet and causing the issue until by accident saw water contamination inside the plug that goes into fuel tank, fixed it and sealed it and issue resolved.