Spark plug PSA

Just got done checking all of my passenger side bank of spark plugs, all now seem to be at least torqued to 13 ft lbs. did not pull any of them, just checked the tightness of each one. During one of my repeat trips to the dealer, they found cylinder #3 spark plug loose and replaced it, after it was throwing a misfire check code for that cylinder.

But I still have a rough idle when the truck has warmed up. Seems to go away a bit when I put it in neutral or park. But when idling in drive or reverse, it's idling rough. Doesn't do it all of the time, but seemingly more than not. Like it's missing.

I took a pic of that #3 cylinder spark plug well and the coil pack. The spark plug well is just nasty and the coil; well it speaks for itself. Do you think that the coil is going bad after the truck has warmed up, not throwing any codes at the moment. Should I replace the coil pack?





Fixing to check torque and coil condition on the driver's side bank of spark plugs next.

 

So I finished checking torque on the driver's side spark plugs. No loose plugs. However I discovered some more things "dealer centric".

I had posted previously in other threads, about misfire codes and other issues, culminating in three ignition coils being replaced on the driver's side engine bank (P0352, P0354, P0356 Cylinders No 2,4 and 6). Well, just discovered that the No 4 ignition coil was never replaced:



Cylinders No 2 and 6 have nice, shiny new coils

Also, looks like they damaged the driver's side insulating cover that goes over the No 6 coil pack. It was broke right in half where it attaches with a screw to the engine head. They just wedged the insulating cover under the intake bracket:





Just disgusted right now. Truck still runs rough at idle when warmed up. No codes being thrown. I have half a mind to buy two ignition coils myself to see if that helps with the rough idling, but the dealer should of replaced them under warranty.

 

Looks like they cleaned it up a little unless it's dirty again because it's still leaking somehow. Mine cleaned up better than that. I would have replaced the plug. The torque for used plugs is slightly different. I linked a page in post #32 that shows doesn't even use torque it uses angle. You can easily check the resistance of the coil with an ohm meter. I don't know the spec but research or a fellow TW member would come up with it as well as which terminals to measure from. Could also compare to the other coils to check for balance.

Why did they replace the plenum gasket? I didn't remove the plenum to get to the driver's side but maybe they did as that's the factory procedure.

 

More bad dealer workmanship. Sorry to hear that. They owe you a new insulating piece for sure as well as the labor to install it.

You can tell that the #4 coil is not new? Does it look like the one in your previous post? I only ask because my coils looked brand new too so I'm curious how you are differentiating. I hope you find the source of your misfire. I just bought one of those OBDII connectors with the OBD Fusion app and it counts misfires. Maybe that would be a useful tool for your diagnosis as well as something to show to your mechanic.

 

Well this inspired me to also check my 2019 OR, at ~25k miles I found all 6 of my plugs to be barely finger tight. Plugs all look ok, coils look in good condition too.

 

How do coils cause detonation?

 

When I looked up the service records on my 17 I found no mention of plugs being changed. Not surprising as it had no records of anything other than a couple oil changes with Toyota anyhow. At 89k (bought it with 88) I changed them. I don't recall which part number I used but it was a denso iridium plug. I didn't find any loose plugs or discolored coils. And it did have the OE plugs in it. It definitely ran noticeably better with new plugs though. On one of my first gens (regular cab V6) I swapped out the plugs for those horrible Bosch platinum plus 4's. Even used a torque wrench to install them (which I honestly normally don't) and those kept coming loose. One even backed out to the point where it pulled the last few threads out of the head and busted the coil pack in half. On a truck that uses one coil for 2 cylinders that was an awful drive home. Used a thread insert to fix it, put NGK's in it and never had an issue again.

 

Yes, post #41 shows the cylinder #3 coil. My later post, #42 shows the cylinder #4 coil that wasn't replaced after I took my truck in for the first visit after it registered the P0352, P0354, P0356 codes.

Both cylinder coils #2 and #6 are new, nice and shiny, Cylinder coil #4 is stained as shown in the picture. It was never replaced.

I really wonder if the new plenum (replaced due to the ACIS shaft inside of it snapping off) on the second repair visit was damaged during installation. How can I check it for a leak?

 

https://www.collinsdictionary.com/us/dictionary/english/twas



Normally I wouldn’t give a shit but since you were a dick in the first place.

Apologies if you were already called on it - TL;DR.

 

Not the plenum gasket, they replaced the entire plenum due to the ACIS door shaft snapping off within it. I posted in this below referenced thread about it.

2016 Tacoma in limp mode, FIXED!

 

Weak spark or too much spark can cause detonation.

 

I'm going to run back to the dealer today and see if they will address the coils that I remarked upthread, as well as the broken insulating cover.

Also, I am also going to see if they cracked my new plenum assembly when they installed it. I will be making a smoke machine of sorts (many of DIY examples on Youtube) to see if I have a plenum or intake leak, or a vacuum leak elsewhere.

https://youtu.be/GOhl4r0GSiE

There has GOT to be a reason for this rough idle when the truck is warmed up.

 

I just got done checking for vacuum leaks on the top end of my 'Taco. The cigar method worked EXTREMELY well, that Harbor Freight pump smoked that cigar like no one's business and I got A LOT of smoke into the top end. I took a pic of the throttle body, I had it taped up well before the test, and you could see the tape ballooning outwards as I was pumping cigar smoke into the top end of the engine.



During the smoke test, I saw a lot of smoke coming out of the area where the blue arrow points towards. The electronic side control of the throttle body. Shouldn't this be well sealed and not leak?


I don't have a can of WD40 handy so I could spray under that to see if the idle increased while the engine was running.

 

Also, just got OBD2 Fusion installed with the 2018 Toyota Add On. The Veepak OBD2 adapter works well with it. A plethora of PID's to pick and monitor from. This thing is better than sliced bread!



Set up a dashboard with Misfire counts on all cylinders. Now I'll know if those coils are misbehaving (I am suspecting No #3 and #4 coils). Better armed with more data to bring to the dealer next week.

 

man, mine has a slight miss at low rpms, especially when cold. might have to torque those spark plugs today.