Spark plug help? ::: Solved

Alrighty,

I hit 60k and decided to go ahead and do my own plugs. Several YouTubes later, I felt confident. I went back to front, passenger side first. Fully completing each plug prior to moving on to the next. Disconnected the battery ground prior and reconnected after.

Fired it up after all six and it sounded good… then it seemed to be missing a little. Drove down to the local gas station to fill up and definitely missing a little. I whipped up an OBD Fusion screen and it’s definitely logging misfires. Added another screen to look at all 6 cylinders. Cylinder 5 is the culprit.

Pulled #5 out and checked the gap and all is good. Put it back in and similar result. Pulled it out and put an old plug back in. That *seemed* to resolve the issue. Pulled that one out and put the new one back in. Same misfire issue. I’m going to put an old one back in and test that theory again.

Any advice at this point?

<edit for solution and conclusion>
Well, my replacement plug arrived in the mail a few days early. Pulled the old-old plug out and put in the new-new plug. No misfires at idle for 3 minute. I’m not going through the trouble of putting the old-new plug back in to test the conclusion that I got a bad plug in my original six.

Thanks everyone for the contributions.

 

What type of plugs? I've heard these are picky about oem/denso only...

 

OEM. I checked the gap on each prior to install. Guess I’ll swap two coils and see if the problem moves. Thankfully it’s #5, literally the easiest plug to change.

 

sub'd for the outcome.

 

How about buying 1 additional new plug for #5 and see if that solves the misfire. Moving the coils may not help if it was running fine on 6 old plugs.

 

If replacing with old plug gave same result, then gotta suspect the coil. Unless you dropped something in the hole. Swap the coul as you suggested.
Also check the coil plug connection. Inside the boot will be a spring. Check that the parts are not bent or broken, or missing.

 

Where did you get the plugs? Amazon and eBay are riddled with counterfeits.

Did you torque them to spec with no anti-seize?

 

yup.
If they seem too good to be true...

 

What did plug 5 look like?

 

Alrighty everyone…. Thanks for the advice so far.

Anti-seize: guilty.
Plugs from Autozone.
Torqued to spec.
Swapped coil packs and the problem didn’t go away. 4 mile drive and several stop/idle.
Swapped plug back out and again it seems to clear up the issue. 3 mile drive and several stop/idle.

Plug #5 didn’t look any different than the others. In general, not bad but they definitely have 60k on them.

I’ll take it to work tomorrow with a cold engine and see how it does. If it does well, then hey, perhaps it’s a bad plug.

 

It’s a little frustrating. The total job wasn’t that hard. Passenger’s side maybe 30 minutes. Driver’s side a solid 45-60 minutes. Debugging??? 1hr so far.

My low profile jack arrived today, so next week the weekender goes up on the stands for its plug change. Gotta take the back tires off for that one. Lol.

 

Get a new plug.

 

The plugs you put in are they denso iridium?

 

My original suggestion would have been to swap the #5 coil to a different cylinder and swap new #5 plug to an other different cylinder, that way in one operation you can see if it follows the plug or the coil.

That said at this point with all the plug swapping youve done I would just go buy one new plug and replace the #5 new plug, most likely that will fix it.

 

Old on the right, new culprit (a few miles) on the left

 

Yep, that would have done it in one go. At this point, I could put the culprit in cylinder 3 and see if it goes there. But the $10 solution is an extra plug at this point. I wonder if Autozone will warranty it for me.

 

Here are some tips working with Iridium plugs.

https://www.densoautoparts.com/spark-plug-installation

 

Bad plugs happen, new just means new, doesn't mean good. I'd get a new plug

 

Have you changed the coil yet? Definitely a fan of doing that to see if the problem follows then replace with new whichever the problem persists (plug if still 5, coil if problem moves to whichever new spot)

Best of luck