Anybody good at reading plugs?

Nope

 

All sorts of maintenance threads here.

You should also read the owners manual to see what’s original for your truck. Yota doesn’t recommend Iridiums for an ‘08 4.0.

I would go ahead and change all fluids and filters. Start fresh with everything including the brake fluid...

Research further about the Auto Transmission fluid- some recommend not changing, others recommend changing...Maybe @gearcruncher can offer an opinion.

 

Can anyone tell me what decrease in engine performance/functionality comes from using an iridium plug in this engine?

I didn’t go with iridium to improve performance. I assumed they would perform the same but last longer. For some reason my old 22-RE did actually run a lot better on Bosch Platinum 2s than the NGK V-powers, that were called for originally, but I don’t expect that from every engine. The iridiums in the 4.0 right now are running great, but that’s compared to some pretty worn out plugs. I don’t know how they’d compare to a new copper.

 

Replace those plugs ASAP. Spark plugs are cheap and easy. Pick up a can of Seafoam Upper Intake Cleaner and enjoy having your horsepower back

 

My truck is at 160k miles I should do the same.

 

I replaced the plugs immediately, the question was essentially whether or not the one darker plug was pointing toward a clogged or otherwise faulty injector. I e decided that cylinder was almost certainly running rich. Once I get through this tank and see how much fuel economy was improved by the plugs alone, I’ll run a tank or two with SeaFoam and see if that cylinder stops running rich. If not, then I’ll be considering a set of matched injectors.

 

Well it sounds like you've got this covered! Good luck and congrats on the best purchase you'll ever make

 

I definitely wish it was a manual. I kinda wish it was the 2.7L.

 

A) you’re surprised that I haven’t had a blowout from running the pressure the tire is rated for, but at far lower loads that it is rated for and far lower loads that would require that pressure? Right...

B) I own two Tacomas. The one that is the subject of the thread is an ‘08 access cab, 4x4 V6 A/T. I’ve had it for a month, but have only been driving it for one week. It came with 10-ply GoodYear Wranglers that are the stock size. The reason I’m concerned about it’s gas mileage is primarily because it was a fair bit below what it SHOULD be. That’s suggests that something is amiss. The dealer had replaced a faulty cat. That sometimes suggests that the engine is either running rich or burning oil. The plugs did not show signs of burning oil, but one may show that one injector is having issues. If the plug replacement brings the fuel economy up to, or near to, the expected 16mpg, then I’ll likely not worry too much about the injector. However, I don’t want to ruin another $600 cat because I ignored a problem that I could have been fixed. My other Tacoma, which came up for other reasons, is a 2010 single-cab 4x4 4-cylinder M/T that I bought in 2010. I have stock size BFGs on it. It still gets the same fuel economy that it did when it was new, and that happens to be right in the zone that was on the window sticker as the EPA estimate. I’m well aware of the fact that the 2.7l M/T is going to get better fuel economy than the 4.0l A/T. That’s not the issue.

I occasionally need some degree of an A/T tire for work, and pretty much have to have one come hunting season. I’ve bounced that 2010 off of every rock in the two states I’ve hunted in, and I was rear ended in it. It has a lot of body damage and paint damage, but mechanicallybit’s in great shape. I only bought the ‘08 because I needed something with more seating. I will continue to use the 2010 to get almost anywhere and everywhere I want to go during hunting season.

 

Why the hell are you even on here if you know everything?

 

Thanks for the info. If an injector is having a problem that causes a plug to read rich, and a fuel treatment improves the injector function, will the plug change visibly, or will I need to use a new plug each time I attempt to diagnose it?

 

Cause I didn’t know much about reading plugs. Now I know more than I did about that.

 

No tire manufacturer is going to recommend any tire constantly ran at the maximum PSI rating of that tire. Granted those numbers are maximum cold PSI but that doesn’t leave a lot safe room for heat expansion. Assuming you actually fill the tires cold. I build tire for a living and I can tell you there are many factors that could come into play when running pressures that high, in terms of the tires being built. There are times when we stretch the plys. Obviously that isn’t ideal, but a little wont hurt. Inning at that kind of pressure you’re stretching everything more. If a component is already weak you’re just adding more stress to the tire. By doing that you’re creating a risk, or in your case more so a liability.

But hey what do I know? Continue doing what you wish. Don’t worry about the multiple deaths that have happened over the years because of tires blowing out.

 

I will always suggest changing the fluid . This means dropping the pan and cleaning the filter and magnets .
Our transmissions are incredibly sensative to debris / contamination in the bottom of the pan .
The worst thing you can do is flush the A750 series transmission without dropping the pan first .
Keep your trans fluid as clean as you possibly can . Why do i suggest this ? because Aisn Seiki valve bodies are 100 percent alluminum . Not only is the valve body alluminum , but the hundreds of valves that stroke 5000 times per day are also alluminum . Any contamination in the pan eventually goes through the valve body working like sand paper on your low mileage valve body .
Waste 45 minutes of your life watching the seminar . The proof is there
https://www.youtube.com/watch?v=eMMTlQPZmqs

 

Awesome! Thanks!

 

The 3 plugs on top appear to be burning richer than the bottom 3 which look correct. Of the top 3 plugs, the 2nd one looks the richest based on the black coloration of the insulator cone. This could indicate that fuel injector flowing more fuel than the other two, or it could indicate that one of the other injectors is flowing less fuel than the other 2 (find the one with the lightest coloration).

The fuel:air sensor for each bank adjusts the long term fuel trims based on the entire bank's exhaust output, so one injector flowing more or less than the other two skews all 3.

I'd use a scantool to read the long term fuel trims (LTFT) for both banks while idling and cruising. They should be in the +5% to -5% range, and both banks within ~2% of each other. Report your findings.

If one injector is flowing too much, you'll see the bank where the top 3 plugs were running skewed lower LTFTs than the other bank.

If one injector is underflowing, you'll see that bank skewed higher LTFTs.

 

The great debate right here. Copper vrs Iridium/Platinum.
BLUF: Difference is minimal, it's your money.


Platinum = worst performance / best longevity but we're not going to be talking about this one.

Copper = best performance / worst longevity
Lets break this one down. It's the stock plug for the 4.0 engine even though the factory installed 2 different brands in each of the banks. This is a big topic of debate amongst the TW crowd and nobody can quite say for certain as to why the factory does this. Copper plugs are recommended to be changed every 20k miles, though the manual recommends changing them every 30k. I follow the manual's recommendation of 30k changes. Copper tends to run at a cooler temperature range than the other plugs which can influence any potential pre-detenonation that might occur if you're planning on supercharging. Also, the cooler plugs help to reduce potential carbon fouling. The electrical resistance of copper plugs are 1.72, since we have 6 plugs, you're looking at a combined 10.32 Ohms across all 6 plugs. Greater resistance increases heat buildup, we'll come back to that one. Price, this is where copper plugs shine at around 2.50$ per plug which should be out the door for 15$ plus tax. The ignition coil packs are the same for both the 2.7 and 4.0 so one isn't any different than the other. PN# 90919A2006 if you're curious.

Iridium = good performance / good longevity
Time to move to the iridiums, as we all know they are the stock plugs for the 2.7. Iridium plugs are recommended to be changed every 90k miles per the service manual. These plugs tend to run hotter due to the electrical resistance. Since we're on the topic of electrical resistance, iridium runs at 11 per plug so with 6, you're looking at 66 Ohms across all plugs. Going back to the copper plugs combined electrical resistance of 10.32 vrs iridum combined of 66, you can see why they are running potentially running hotter. The 2.7 engines electrical system is designed to handle 4 idiriums whereas the 4.0 is designed to run coppers. Some supercharger fanboys will swear by the iridiums if you supercharge, but from what I've researched getting the proper rated coppers are more efficient if you are on the blower train. The spark delivery (vitality? vigorousness? gumption?) tends to fall off over the life span of the plug so if you happen to get all 90k miles out of your plugs, you might find that the gap is extremely out of tolerance. It might be in your best interest to periodically check the gap of your iridiums every 30k and check how your engine is performing. There's potential risk in breaking the grounding strap of the plug if it has become brittle over the course of its life. I dont buy Iridiums from the dealer, so I cant say what they run there but Amazon seems to be running a 6 pack for 57.59$ PN# SK16HR11 so ill base my math on that number below.

Lets run those numbers:
If I buy coppers and change them at the recommended time of 30k on the dot, I'd be looking at 3 changes to get me to 90k including the first time change. That will run me a total of 45$ for 90k (tax not included).
The Iridiums will sit me at 57.59$ every 90k (tax not included), so you'll save yourself about 12.60 (again, tax n stuff).
Now though they dont tell you to check your iridiums over the life of the plug, but if you do pull your plugs every 30k and verify the gap/health of the cylinder, why not just plop in a new set of coppers gapped appropriately? You're already there for petes sake! #smh #yeet .. is that what the cool kids are saying these days?

So to wrap this up, checking your plugs every 30k is good. Copper is cheap. Iridiums run hot. 4.0 ign system is designed for copper. Gap them bitches with your gapper flapper. Iridium service life falls off towards the end of its service life if not babied. Why not have the peice of mind of new plugs every 30k since you "should" be there anyway? #fin

-J

 

Awesome! Thanks! I’ve been meaning to get a scan tool of some sort. Now that I have two Taco’s and a 4-Runner of similar years(‘06-‘10) it really makes sense.

 

Finally someone with a better answer for which plug than “because the manual says”!

In this particular case, the iridium plugs are already in the engine. I put them in the 4.0l when I pulled the ones in the picture. I honestly didn’t check plugs on my 2010 2.7l because fuel economy has pretty much never changed since I bought it in 2010. Around 150k miles I decided they probably needed to be changed so I ordered plugs for it and a Camry. When I got them out, they gap had opened, I don’t remember how much, but I remember being VERY surprised at their condition. Brand new plugs seemed to change nothing. They may need to be checked more often in the 4.0l, but in my 2.7l I see no reason to check them more often that 90k miles unless engine performance or fuel economy points toward a potential problem. I’ll make it a point to check the iridiums that just got put into the 4.0l.

When you say that the electrical system in the 4.0l isn’t designed for iridium, could you tell me which component would be causing the problem? If the coil packs are the same what would the difference be? Is there definitely a different input to the coil?

 

Save from actually getting out there and putting a multimeter on the coil connectors on both the 4.0 and 2.7, I'm going to fly from the logical seat of my pants on this one. As a precaution, this is merely speculation on my behalf without getting my hands on the engineering documents. My thinking regarding is actual number of wire runs from the battery's positive to the coil packs and how it gets there. How many times is that wire connection broken via plugs and wire harnesses? If we break it down to the simplest run of a positive wire straight from the battery to the positive terminal of the pack, then a second wire straight from the pack to the ground gives us 12 wires for the 4.0 and 8 wires for the 2.7. The battery will run to a fuse before it heads to the coil packs logically. If both fuses match from the 4.0 to the 2.7 then there shouldn't be much difference other than the physical number of wires running in the wire harness themselves. The internet is running archaically slow so looking up fuse block diagrams is taking forever so bear with me. Physically chasing the wire would tell us how many connections it makes. Each connection has a potential for static loss of amps through measures outside of our control, like corrosion for example. Additionally, the amount of wires within the wire bundle also adds to potential heat gain through resistance which is why it is recommended to keep that in mind when determining wire runs on top of length of said run. For example, if you have 10 16 gage wires tightly wrapped will generate more heat through resistance than say only 4 16 gage wires through the same bundle. There is a formula for this which I'm trying to pull up but you can thank our slow internet speed for not bringing up that super exciting formula so you'll have to take my word on it or look it up yourself. It's the same reasoning behind limiting the number of wires through conduit in the housing/building code.

Based on this information, I can rightly assume that the way the wiring harness is built and routed in the 2.7 is different by either the amount of wires in the bundle or the length of the run. While the wire might be able to physically handle the current draw of the iridium plugs, you'll still run a risk of burning something up no matter how negligible the draw. This is why I personally make an effort to use the recommended components. With this choice, you're changing the point of failure from the spark plug or ignition pack themselves to some other component that might not be correctly rated to handle the increased current or heat from resistance. Electricity isn't something to take lightly if you aren't exactly certain on what is going on, its a good way to bbq your baby.

Bottom line, I cannot speak with certainty without more information directly pertaining to the differences so unfortunately you only have my word to take. Perhaps others might be able to chime in with additional information.

-J