spark plug/ignition wires?

Hello, I bought a 2017 sr5 with 118k mi on it a few weeks ago. yesterday, my CEL came on with the TRAC OFF light and a rough idle. Threw code P0301, cylinder 1 misfire. Being at 100k+ with an unknown history, I went ahead and changed all spark plugs AND ignition coils. This is where I ask you to please be nice, as that is mostly the extent of my knowledge as a backyard "mechanic". The lights went away and idle got smooth for about 24 hours, then it started up again: rough idle and both warning lights. Doing research, I came across the conclusion that it is likely my spark plug WIRES? My question, which may be a silly one, is where are my spark plug wires located, and how can I replace them?? For some reason, this is a completely dead topic on google and Youtube and I feel like I am missing something obvious, lol. Can anyone provide a pic/diagram of the actual spark plug/ignition WIRES? TIA

 

The ignition coil is the “wire”.
What name brand were the coils?

What are the current codes?

 

Ohhhhhh okay that’s starting to make sense. The coils were called Carquest premium.

I’m going to get the codes read again now, I don’t have a reader.

 

As stated, you dont have spark plug wires, & you shouldn't just replace spark plug wires on a high mileage vehicle without doing spark plugs.
In your case, you have individual the hangout above the valve cover....
If youre just going to throw parts at it vs diagnosing it...
You will need to replace your coil boot & spark plug, dont ever do a plug without a boot,
The boot gets carbon tracked & will just transfer / damage the new plug & continue to misfire...
Also your valve cover sparkplug well o-rings which is pretty much your valve cover gasket could be leaking engine oil onto the spark plug & coil boot...
If its saturated with oil, just replacing the plug & boot would be a temporary band-aid....

My point, could get complicated & not as simple as just looking on the internet for causes.
Also dont recommend driving with a misfire, as raw fuel getting dumped into the cat converter will overheat & damage the very costly cat converter..
good luck

 

Typically the Toyota ignition coils aren't a wear item and can last the life of the vehicle. A more efficient way to confirm would have been to swap the coil from cyl #1 with that from neighboring cyl #3, and see if the misfire moves to cyl #3. Water under the bridge now.

After replacing all the plugs and coils, have you confirmed the code is still cyl #1 misfire? If it's still cyl #1, that rules out bad fuel quality. The fact it ran fine for 24hrs makes a low compression less likely as well. Could be a bad #1 fuel injector or mice chewed wiring to either the #1 fuel injector or #1 coil. Remove the intake tube between the airbox and throttle body and examine the aforementioned wiring. #1 cylinder is passenger side frontmost cylinder, so access is a bit easier.

 

Sorry, didnt read that you already replaced all coils & spark plugs.
Question now is, same code p0301?
If it is the same code....
Could be an injector, could be a cylinder with low compression, needs to be diagnosed vs rolling the dice.
Or, remove spark plug & inspect, verify gapped correctly...
can be a numerous reasons....

 

I had a series of misfire codes in my 2008 T4R, which doesn't get driven much except for wheeling/road trips (just enough to stop the battery from running down) which went away when I put a half tank of fresh gas and some injector cleaner into the tank. Not driving much means that sometimes the gas in the tank can get to be 5-6 weeks old, and I'm not as diligent about adding stabilizer as I really should be.

I won't promise that it'll fix things, but running a tank of chevron premium and some lucas injector cleaner through the engine isn't very expensive and can't possibly do any damage to anything.

 

Also, do you have a V6 or 4 cylinder?

 

Good point but both a coil on plug from research I did...
My toyota engine specific characteristics / common faults is very limited other than head gasket issue on the v6....

I can go all day long, when it comes to ford, you name it, theres a list of common failure points...

 

OP, I am happy and admire you for trying to fix the issue yourself.
But this is a case where it would have been nice to catch you before you tried to fix it.

The chances are, those coils you put in, will fail in the future.
Toyotas in general don’t do well with Non-OEM ignition parts or sensors.

I’d keep your old coils. Just for spares if you need them later.

Until then, get us the current codes.
I’m hoping the code(s) are different.

 

True, I thinking a cylinder 1 misfire could feel different depending on the number of cylinders.

 

officially, you shouldn't gap iridium-tipped spark plugs. they should come pre-gapped. or in other words, the gap doesn't matter like it used to.

but you neglected to tell us what brand of parts you used.

non-oem coils are well known to be inconsistent in performance. i don't like paying oem prices, but this is a situation where it results in trouble-free operation. each coil has a lot of high-tolerance electronic components in it to get the timing of the spark output correct. it's easy to undercut toyota-spec stuff by using a larger tolerance of electronics, but results in a less consistent spark output, and life span of the coil.

second, the plugs needs to be a specific DENSO plug. again, i specifically recommend getting them from a dealer, despite the cost, because other brands or sources generally don't perform as well, or are outright knock-offs. Amazon, and ebay have both had their share of documented plugs that appear genuine, but are entirely fake, with some working good, to others just being a hunk of non-conductive ceramic that can easily break off and damage the engine.