FIXED!.. I think ;) Need help chasing down sudden rough idle!

if the wires don't solve my issue (and I doubt they will) I will pick up another coil pack and try swapping them one at a time to see if it solves anything. even if it doesn't, it never hurts to have a spare.

I think you got the wrong plugs, the two prong plugs for the 3.4 engine come pregapped at 0.43 and these are different plugs then what is used in the 4 cylinder engines which use a different gap setting

 

You know what, I'm not convinced about the default gap set by the dealer only because of what I say earlier in this thread about getting the new NGK plugs first, and seeing they were factory set to .021-+. Both NGK, and the Toyota Dealer plugs are not supposed to be gapped. Besides the indicator of the plastic tube on the threads (supposedly that indicates that they're there to protect the electrodes from moving from their set positions while in the box/transporting/shipping, etc), is the info I've read online (NGK related) that says "do not gap" and the people at the parts dept. at Toyota that exclaim "do not gap these Denso plugs!"

1. What doesn't convince me about the gaps is why two huge companies like NGK and Denso have different gaps for the same application...???
2. And why is the only spec that I can find from Toyota for our specific 3.4, V6, 5fze trucks - state that the gap is supposed to be .044 when the appropriate plugs are dual electrode that require .021-.025 gap from each electrode to the center electorode... ????????? Freakin head cracker trying to figure that one out.

I've even thought that this may be why I have some residual small tremble in my idle some of the time.

 

my dual electrode denso plugs all came from the dealer in a sealed box properly gapped at 0.43.

someone is not giving you, or you are not asking for the right plugs

 

Something doesn't add up. I won't quote the part numbers I've used because I don't remember off the top of my head what they were, but the numbers are in many of my previous early posts. The part numbers are 100% correct on both of my purchases - first the NGK's and then with the dealer Denso's. I can't tell you how much time I spent alone just triple, quadruple, quintuple, (you get the picture) checking those particular part numbers before, during and after all this.

I'm not alone. Other related sites have users confused as to why the gaps are the way they are. If you got them from the dealer, and you measured with a good multi blade gauge tool, and the factory set distance from one of the electrodes to the center electrode is .043 and so is the other electrode to the center, then I don't know what because your plugs would be an anomaly from everything I've read (I've spent about 3 months researching tons).

The only other explanation I've found (maybe this is what your situation is if I'm not understanding correctly), is that when the distance from both sides of the dual electrode to the center electrode are added together, then you get about .043-.044. and even that doesn't make total sense in the case of the plugs you'd think are the fail safe - the dealer plugs which are .025 each side to center electrode. .025+.025=.050. Still, everything I've researched says to not gap either the factory NGK's or the Densos.

 

these are the type I bought http://www.ebay.com/itm/6-PCS-TOYOT...NGS-K16TR11-/141721201644?hash=item20ff3debec

denso k16tr11 and they come gapped at both prongs .043 from center electrode and it is impossible to gap them with a feeler gage, you have to use a wire gap tool like pictured below to check the gap because the prong has a curve to it to follow the shape of the center electrode. I rechecked all gaps to be sure but they were all spot on right out of the box on the denso but the ngk set I bought the first time, I had one plug with one prongs gap that was off

 

Each gap should be .043" checked with a wire gauge because the electrode is curved. A blade can not measure a curved gap and if used will show a much smaller gap.
The person on the phone at NGK was wrong, there is no "adding" the gaps. Additionally the spark fires across one of the gaps until it erodes to the point that the other gap is an easier path. Back and forth thru the life of the plug.
Both plugs for a given coil fire with opposite polarity (they are in series), one from center to ground and the other from ground to center. After some time the "wear" will look different.
Both the Denso and NGK plugs are pre-gapped, sometimes perfect sometimes not. NGKs have been known to sometimes come pre-gapped with the incorrect gap (smaller).
I have bought and installed at least 100 Densos, 7 sets in my truck alone and they were all .043" aside from one here and there slightly off.

And of course everyone knows that the 3.4 came from the factory with 3 Densos on one side and 3 NGKs on the other.

Stolen pic.

 

Well there you go. I, as well as many other people, were unaware of using the wire gauge to fit in the groove of the electrode to get the proper distance measurement! I guess you guys knew that when I mentioned using the blade gauge. Therefore, since I didn't gap my dealer plugs, I can somewhat assume that they are gapped properly. I'm glad to have learned something new today.

It's funny, I even went back to the dealer to show the guy at the counter the "weird" .025 gap with my blade gauges, and he had no explanation. Apparently, even they all don't know, and they're the dealer! Where were you guys at the beginning of this thread!!! Haha!

 

those guys at the parts counter often don't even know enough to change plugs. just because they work the counter doesn't mean they know anything.

you should only take advice from actual mechanics to rely on and even then be skeptical that it may not be 100% accurate

 

You know how often I've wished I could walk back into the repair bays to pester a mechanic with questions? Unfortunately, we can't do that. It would be great to have a mechanic who specializes in our particular vehicles at our disposal, but most of us don't. These forums help somewhat, they really come through when a poster gets lucky enough to write a post that's seen right off the bat by an actual mechanic who know what he's talking about, rather than lingering in page after page of posts (which the help is obviously appreciated, but kind of like my thread here). I know many actually do belong to these forums and contribute greatly or to a large extent.

 

there are several regular mechanics on here and many genuine certified mechanics and there are some that are the absolute know it all as far as the correct way things should be done so trust me you will get some help from them if you ask for help from trained mechanics in the thread title.

DP is one of those guys I would consider to be an expert on most things and I wont list the other for fear of omitting some but there is no shortage of trained Toyota mechanics on these forums

 

Good to know.

 

Holy crap... this is me!
I searched for rough idle and came across this thread. My 03 V6 Manual Tacoma does this exact thing as you mentioned above.

I see you replaced a coil pack. How should I go about testing each one of mine ot determine if it is in fact one of them acting up?

 

I'll admit I didn't read every single post so this may or may not help you or maybe someone has already mentioned it, if your still getting a rough idle, make sure you tightened that flat looking braided ground wire that's bolted to the intake on the drivers side when you did the plugs. I changed out my plugs and wires last year and only hand tightened it during tear down so I wouldn't forget where it went when I put it all together, well I forgot to torque it down, and the truck ran/idled like shit until I snapped that it was loose. New O2 and MAF sensor later, that was the problem the whole time...like I say may be irrelevant but it could help you.

 

Very useful thread...I need to buy a wire guage when i change the plugs - - just hitting 150k on originals.

 

what's proper resistance for a plug-wire? specifically 5->2 ... been trying to track down a rough idle condition that has finally thrown a code for mis-fire in 2 ... changed injector, new plug (mostly properly gapped - ngk (all were gapped small near .03+)). i went ahead & ohm'd the wire - only reading 1619ohms set on 2K.

This is the closest thread i've seen for very similar issue - changed all my wires, plugs, & coils early march of '19