What to do with my Prius and the Stealership

So my car has been through two sets of spark plugs and it still seems to misfire after long and frequent stops. I I deliver meds to nursing homes so I do alot of miles. The hybrid system lights have come on once in a while, about 3 times in the last 3 months. I took it to the dealer and they said that the check engine light was on due to the misfire. They told me that they received a code for the hybrid system computer which is still covered under the warranty. They told me that the misfire could be causing the hybrid system computer code to come up. They told me to replace the spark plugs so I did. Well, now the car is still misfiring, although not as much, and they told me that it could be a coil pack, I have already replaced one coil pack on my own. Also, they told me that it the check engine light comes on again then I should bring it back in because it might really be the computer that needs to be replaced. What should I make of all of this? Should they really be replacing the computer now and they are just giving me the business? Please help!

Have they cleaned the throttle body? This is a common problem for earlier Prius.

Tom

Have you changed or checked your Spark plug wires?

How many miles on the odometer?

Prius does not have spark plug wires.

Rather than blindly continue to replace parts, I suggest that you need to identify what DTC (diagnostic trouble code) has been logged by your car. Then you'll have a clue about what the problem is, including which cylinder(s) is(are) misfiring.

What caused you to replace one spark igniter (aka coil pack), and what did the other three look like? Any corrosion, cracking, burn marks, etc.?

Did you use the correct NGK or Denso iridium spark plugs; or some other brand? If the latter, that can be part of your problem.

Did you check the new spark plug gap (1 to 1.1 mm) before installing? Are the spark plugs properly torqued to 13 ft.-lb, and the wiring harness connectors snug and tight? Check the connectors to the spark igniters and the fuel injectors: any corrosion on the terminals?

Usually a cylinder misfire can be attributed to the spark plug, the spark igniter, the fuel injector, the wiring harnesses feeding the spark igniter and fuel injector, or bad cylinder compression.

63,000 miles on it.

How's the 12V battery? A low or failing 12V battery can cause all kinds of "ghost problems".

But I'd have a look down the throttle body. It's easy to check, just remove the air cleaner and you can stare down there to see if it's black with soot and other junk.

swap coil packs around and see if your misfire code moves around to other cylinders in response. if not, you know the coil pack is not the problem.

... Brad

Haven't dug into the engine compartment and am curious? No plug wires correct? Does coil pack / connectors replace what would be the coil and plug wires in older model cars? Spark igniter / other name for spark plug?

Interested in how this works.

You can see the tops of the spark igniters if you take a look at the engine valve cover. The tops are small, black, and rectangular and have a wiring harness connector which provides low voltage pulses from the engine ECU to fire each spark plug according to the correct timing.

If you were to remove a spark igniter, you would see that it extends several inches into the engine head. The spark igniter contains the individual ignition coil for the cylinder, and the bottom of the igniter has the high voltage coil output.

The spark plug sits immediately below the spark igniter, hence no wire is required to connect the two components.