JeffTexas7

Howdy
Got the dreaded P0305 cylinder plug misfire detected. Ended up being quite easy for me to resolve. I havent fixed it yet, but I was surprised how little help all the forums were and you tube. It ended up being a bad spark plug. Not the ignition pack. I was surprised nobody mentioned moving the ignition pack and plug to another cylinder to see if the code changes cylinder. Also, I noticed if you run the engine, and pull out the ignition pack, you can hear it firing in the tube. A good way to test the pack itself.

Here is the simple troubleshooting.
(drivers side, 1-3-5-7)
Pax( 2-4-6-8)
That is front to back

-ID which cylinder with scanner or by pulling each chord to the cylinder pack. If there is no change, thats the bad cylinder.
-pull out the ignition pack. Mark it, and swap it to another cylinder. Clear the codes, and restart the engine.
- if the new code shows a different cylinder. Its a new $85 pack.

If not change, try moving the spark plug itself. (That is what happened to me)
- I moved the plug to a new hole, and guess what. The code when from 5 to 3.
I also noticed if I ran the engine, and pulled the ignition pack out a few inches, I could here it fire in the tube. I wish I discovered this sooner. By doing this, I knew two things... the ignition pack was getting power, the problem was likely down stream of the pack.

Im heading to the store now for a new spark plug. The only hard part was getting the right length socket extension to work. I used 3 extensions to come up with just the correct length to the wrench.

Coleroad

Glad you got it resolved. I am confused about the lack of help from the forum statement. This looks like the first time you have posted the problem here. Was it not answered somewhere else?

Bgw70

Sure enough, I did an advanced search and there has never been a thread on fault code p0305 in the SC430 forum. Other forum areas have it.

so, you are the first in the SC430 forum and you gave a good set of instructions for others to use. Thanks! And welcome.

Coleroad

Ok, I get it now. That there was not a thread already discussing this issue. Thanks for adding to the book of knowledge on here.

JohnnyCake

Definitely thanks for the post. You have definitely helped someone. In the words of Bogart, "Maybe not today, maybe not tomorrow, but soon....."

Chaditotx

iTrader: (1)

I went through a similar issue on a 2014 4 runner. Changed plugs, swapped coils, decided to start motor with plug and coil out on offending cylinder. Couldn't smell any fuel. Squirrel had eaten through injector connector on #6 . Took me a minute to figure out

Jabberwock

Was there any discernible visible damage or wear on the bad plug?

Coleroad

You can also run mode $06 diagnosis. With this you can spot problems before they get to the point of setting a cel. Something good to run periodically to find failing parts before they leave you stranded. It should also be part of your pre purchase inspection.

HardTimes

Today is the day!! Thanks y'all for the thread and droppin' the knowledge. I've been posting a lot here lately about all I've been doing to my SC. I've driven 3 or 4 days now with no error codes popping up - was feeling pretty good about myself and my SC, until .....

Driving home from work tonight (had to step into the gas to hear the Injen) and thought I heard a "pop" from the engine compartment - engine sounded a bit different. The car also became "doggy" as well as came up with the VSC/VSC OFF lights and CEL. Hooked up my code reader and came up with P0306 - misfire cylinder 6.

After glancing this thread, opened the hood and swapped coils from cylinders 6 and 4 (adjacent cylinders - KISS!!) Cleared codes and test drove down my street. Code reappears, this time P0304 - misfire cylinder 4. Eureka!!

Planning on going to O'Reilly tomorrow to get an (expensive) aftermarket coil so I can run the car to verify hitting on all cylinders and problem solved. Then I plan on locating a Denso OEM to swap as soon as it comes in. I have a service appointment scheduled for Wednesday so need to at least get the car running well temporarily .... lol.

Thanks to ClubLexus and especially SC430 contributors. This is truly an invaluable resource. I can't tell you the despair I felt when I saw the P0306 code pop up with all the new symptoms. If I can get out of this with a simple coil-over-plug replacement, I will be delighted!! Time will tell.

DshngDaryl

you could probably get a denso over nighted to you from Amazon. That way you save the cost of buying a temporary one

Cavedog

Same code on my old LS430. Swapped coils and the coil was bad. Gambled on eBay part for $11 and won. Ran till I traded for an LS460.