2001 Corolla - Clinder Misfire, Catalyst System Failure, ECAP

[crispy1260]

2001 Toyota Corolla - 177,000 miles

My codes when reading the engine codes are

• P0304 - 4th Cylinder Misfire
• P0420 - Catalyst System Failure (Had this before the current problem)
• P0446 - EVAP System Vent Control Circuit

When idling or in drive, the engine shakes and I can hear the engine tripping as less air randomly gets pulled into the engine.


Recently, I have replaced the spark plugs and replaced a spark plug boot on Cylinder 4 due to oil leakage into that cylinder(should be fixed now).

Note on my P0420

I have read that the P0420 can be triggered by other engine issues so I have not been looking to deeply into that one. Also, the dealership and a few smaller shops couldn't figure that code out.

​

What would be your order of things to check when diagnosing the errors?

 

[crispy1260]

Solution to my problem was I had an engine coil go bad on me in cylinder 4.

 

[con-man1]

:thumbsup:

Solution to my problem was I had an engine coil go bad on me in cylinder 4.

Thanks for being one of the few that comes back and post the solution.:yes:

 

[Scott O'Kashan]

Keep in mind, that's a guess, not a solution.

Diagnose before spending your money on a potentially totally unneeded part.

 

[crispy1260]

Problem Still Fixed.

Well, either way it fixed the problem and it hasn't reoccurred yet so I would think it is safe to say I got unlucky with a badly constructed engine coil.

 

[Scott O'Kashan]

:thumbsup:

Thanks for being one of the few that comes back and post the solution.:yes:

Here, here! :clap::thumbup1: The folks who posts questions asking for help with their vehicles who then receive it and never reply as to the end result, they sure get old. It seems very selfish to me not to share that information with others here in the Corolla Forum so everyone can benefit.

 

[porschpow]

How do you diagnose a bad coil???

 

[Kev250R]

This seems to be a fairly common problem on a lot of modern cars. The way I've checked in the past is to swap the suspect coil with another cylinder and see if the problem follows to the new cylinder. Most of the time each cylinder has it's own coil or shares one coil with two cylinders.

Kevin

 

[IFMJohn]

Sometimes you can swap coils.

You can do a resistance test on each winding to see if they are good.

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[porschpow]

Are you able to Take the bolt fastening the coil pack off aand remove the coil a little bit to see if the idle changes? (while the car is running)

 

[IFMJohn]

Why would unbolting the coil pack effect the idle?

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[IFMJohn]

Nevermind, I see what you're saying. Could you? Sure. Ideally it would kill one cylinder.

Would I? No. Ever been shocked by 50,000+ volts? I have and I don't want to do it again.

I would swap the coils and see if your misfire moves. On your vehicle all coils are the same so its not an issue.

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[porschpow]

I don't have the scanner with me.I saw youtube videos of people lifting the coil a little bit off the spark plug to see if the idle changes

 

[IFMJohn]

You could do that. It would kill a cylinder. If your idle does not change then that cylinder was dead all along.

I wouldn't do it because I don't like getting shocked by tens of thousands of volts.

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[porschpow]

Do you know where #2 Cylinder is?

 

[Donabed Kopoian]

Get a multimeter, and I really do not recommend unplugging any electronics while the engine is running, including ignition system components. If you really can't get a multimeter, then shut the engine down before disconnecting anything. You shouldn't need the engine running while messing with a coil pack to tell the difference in idle.

Cylinder #2 is the second one from the drive belt.

 

[Donabed Kopoian]

And you can unplug the coil connector and accomplish the same task without having to completely remove it.

 

[porschpow]

gotcha, where would you hook up the multimeter to? Would you be checking for curent or voltage?

 

[IFMJohn]

You'd be checking voltage at the coil packs. Remove that connector from the coil packs and check for voltage on pins inside the connector (the one hooked up to the wires, not the connector on the coil itself).

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[IFMJohn]

Wouldn't you need to check that with the engine running though, Donabed?

*Disclaimer: the engines I work on don't have ignition systems so don't listen to me.*

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[Donabed Kopoian]

Yes, the engine would need to be running to check for voltage at the connector, but to check the coil itself, you'd check for resistance on the terminals at the ignition coil (engine off).