Spark plug wires

What problem would that solve?

 

All Prius cars have a direct ignition system (distributorless ignition), with a separate ignition coil for each cylinder. The spark plug caps are part of the ignition coil assemblies, so there aren’t high-voltage spark plug wires like those in conventional or transistorized ignition systems of older design.

Indeed, the wires to the ignition coil assemblies are part of the engine wire harness. Unless there’s a problem that can’t be repaired using the methods described in the Electrical Wiring Diagram (more info), there should be no need for replacement.

 

Replacing that wiring harness would be very expensive, a lot of work. and unlikely to prevent any future problem. Best to leave it alone. The biggest threat some people face regarding the engine wiring is rodents chewing on it.

 

Hi everyone,

I need some advice regarding a problem with my 2019 Toyota Prius (75k miles). Recently, during a full service, I replaced the spark plugs for the first time. Before this, I had done several services but hadn’t changed the spark plugs. My combined MPG used to be around 67, but after changing the spark plugs, it dropped significantly to about 55 MPG.

There’s no error on the dashboard, but I’ve noticed something unusual. When accelerating sharply at speeds of 20-30 mph, the car feels a bit shaky, like it’s producing less power. I checked the spark plugs, and they’re fine—they were purchased from a Toyota dealership.

However, I did notice that when the mechanic was replacing the spark plugs, he struggled a bit to put the connectors back in and removed a small red rubber piece from the connectors. I’m wondering if this could be causing an issue, possibly leading to a misfire in one of the cylinders.

I’m completely clueless at this point. Could the connector issue be the root cause, or could something else be wrong? Any advice from the experts here would be greatly appreciated.

Thanks in advance!