Very interesting and informative article, thanks!

 

Based on this and the OP, I went ahead and purchased a set of the E3 Diamond Fire Plugs.

Then I started reading the rest of this thread, including:
Am I going to regret my purchase of the Diamond Fire Plugs?

 

I've been looking into the e3 plugs, and the comment by josh is the only real criticism I've found so I'm going to go ahead and install them.

Does anyone routinely use a spark plug chaser just to ensure the engine block threads are clean?

Below is a link to the official e3 torque chart, which recommends 18-22 ft-lbs (or 1/2 - 3/4 turn) for 14mm threads in aluminum engine:
http://www.e3sparkplugs.com/torque-chart.php

18-22 is considerably more than the 13 ft-lbs cited as the official specs for the Fit. However, these plugs may -- or may not -- require 18-22 ft-lbs in the Fit.

My biggest concern with this job is over or under tightening, so I'm really not sure what to do. Also, I don't have a torque wrench and I'm reluctant to spend $$ on an accurate one that I'll use twice a decade at most.

 

3/8 torque wrench at Harbor Freight is $9.99 with motor trend/ car and driver coupon.

If you don't have the confidence stemming from experiencing installing plugs, I would highly suggest buying the torque wrench. The repair of damaged thread is so much more.

I would not use plugs other than OEM NGK or Denso... There are many reasons, and plug do vary significantly. The safest is to use the manufacturer recommended spark plug.

 

TSC also has a $10.00 torque wrench. Some 3/8" and 1/2" drive torque wrenches start at 10 ft-pounds. and are not very accurate in the first 10% of their range. You might want to get a lower scale inch-pound one and multiply the ft-pound number by 12. You also might have to get a lower range 1/4" drive one and use a 1/4" to 3/8" adapter for your 3/8" socket if necessary.

1/4" Torque Wrench - 20-200 in. lbs.

3/8 in. Drive Click Type Torque Wrench

I did not check their sale catalog but they usually have them on sale for $10.00 to $12.00.

If you can tell the difference between 13 ft-pounds and 25 ft-pounds without a torque wrench then you are much better than I am and I have been turning wrenches for more years than I want to admit to.

I do not torque everything I do, but anything in aluminum, like spark plugs, is very touchy because they are torqued so low. If you get them too loose they will eventually blow out of the cylinder. If they are too high you stand the chance of stripping them or galling the threads the next time you remove the plug. If you use anti-seize on the threads, add 10 to 15% to the torque spec. 13 Ft-pounds is not much. Compare that to a wheel nut which is normally 80 to 100 ft-pounds depending on the stud size and nut style.

You might be able to borrow a torque wrench for free at AutoZone, Advanced, etc.

Use a torque wrench on those plugs. Why risk it?

 

I installed the e3 plugs last weekend, without a torque wrench. I tightened about a half turn with the wrench after finger-tightening. I had a pretty good feel for compressing the washer up to the point where it felt appropriately crushed and resistance increased to more turning. I'm pretty certain I didn't strip any threads and fairly confident it's tight enough. So far, so good. The car is running much better with new plugs & coils.

 

The video below adds some more information to the excellent tutorial on the first page. I hope it helps!

 

I just did mine, it was easy as pie. The best thing to do is to unscrew the support for the ignition wires, the left side screw, and the 2 top one under the engine cover. That way you can push/pull the wire support out of the way. The no 3 and 4 cylinder are harder to do, but if you take your time and do it careful, it's not that hard. There's a lot of room behind the engine for your hands.
I did not take step by step Pic. ( those ons on this thread are good) But here some pic anyway.
As you can see, my car does not have a lot of KMs on it. ( yes it is dirty, It need a clean up badly, but my time and will are occupied on other thing lol )



You see those screw missing on top? that's the ignition support screws I talked about.



My Spark plug were not Denso, but NGK, I know they use both, probably depend on suppliers. They are IR ( laser iridium long life I thing) I don't know how long they last, but giving the Denso 120K miles lifespan, I guess it's the same for them. So mines have a little over 50% into their technical lifespan. but they did not look too bad.


I replace them with denso Iridium power IK20L. I bought those because I got a good price on them, and I thought at first the lifespan was similar. I was wrong, but now I have them, and I have my face in the engine bay, so I'll change them anyway. I don't think those Vs the long life will make any performance difference on my car beyond placebo effect. engine is stock after all. They will last only 20-30K miles, But it's was fun job to do and not hard at all, so I don't mind changing them every 3 years. ( I will own my car for another 4 years maybe)

So the heart of the why I was doing this was that, like a lot of FIT owners, I had a unsmooth engine, hiccup, some misfire. But, mines were not regular, did not spawned any Check engine light. so it was hard to know exactly what was happening ( I don't have any diagnosis tool beyond a code reader, and since I had no CEL, It was useless). This is my coil packs right out of the engine.


The exterior is dirty, but otherwise, the connectors looked ok. But I used a electric connection cleaner on the coils anyway. You just slowly ( require some force and twisting) pull on the elongated part, and it will come off. There's a coil in there with something that look like a fuse ( no PIC), I cleaned that and the connection inside the black box part as well.


I put a little dielectric grease on the Plug ceramic part ( not on the coil red rubber, because It could get on the connector, you don't want that) and I did not used anti-seize. There was no trace on any on the stock screws and plug and they unscrewed easily anyway.
I re-torqued them with 22-23 N.m ( the spark plug box/ honda and Denso site said 20-30 so that in just in between) it's around 15lb-pi. around 7 for the coil screw ( although I could not use my torque wrench for 2 of them because of his size). That's was a fun job, I listen the podcast ( the Skeptic's guide) while doing it. Now I'm ready to do my wife's Corolla too! The Corolla SP are right in your face, on top of the engine, it's going to be a piece of cake compare to the fit, and fit was not really hard.

Anyway after a 30 min test drive, the engine was smoother and no misfire, or hiccups. Lately when I was releasing the clutch smoothly at low RPm, after a stop or traffic light, I would feel like my engine lack power, it's gone now. Of course, I would need more test and time to be sure, and maybe the problem will come back, but for now the difference was significant. So maybe it was the SP.

I Bought myself a really good true RMS multimeter ( Amprobe Am-530, Fluke are to expensive for home use, I do electronic, so I needed it), but I have not received it yet, So I could not test the resistance Like I wanted to do at first. But if the problem come back, I test that.

P.S I apologize for any spelling/grammar error, I proof read it, but English is secondary to me ( French Québecois)

 

Thank you very much for the photos.

Do not worry about your English. It is a lot better than my French and I lived in France for a period of time. I never learned the language. I relied on others to translate for me.

 

Small update. I did my spark plug despite the low mileage on them because I had some issue thinking it was the Coil pack Or the Plugs. But I was doubtful it was the plug. They did not look bad when I changed them. but my issue are gone. So or it is the plug or the cleaning of to electrical connection on my Coil that did the trick. So I don't need coil pack. I'm happy, a lot cheaper this way.

 

Thank you sooo much for this DIY/walkthrough! I just replaced my 2008 Sport MT with the NGK plugs (#6774) and the Beck Arnley coils (#178-8374). I was a little unsure of how to do the dielectric grease, so I just did as in your pics Sid. I also paid carefult attention to how tight I did the plugs. Cranked her right up and drove around the block a few times. The car no longer STALLS out when cold, and no more sputtering or hesitation that I can tell! RockAuto had the best deal. I got the coils and plugs for $233.00 shipped. THANKS AGAIN!!!!

 

So I followed this thread while changing my spark plugs (for the first time, regular maintenance). When I pulled off the last boot it came apart exposing the spring. I put it back together, not thinking much of it. I started to get a misfire every once and a while after that. The boot end was black so l changed that boot and spark plug (just in case) and took it for a drive. It went downhill fast and I got a code for a 1 cylinder, 2 cylinder, and random misfire. One of my other boots was black too. I used autolite iridium spark plugs. Any thoughts?

 

Per the Honda Fit / Jazz GE8 2008-2014 shop manual.
Replace Spark Plugs every 100,000 km (62,500 miles)

Spark Plug Inspection
Remove the spark plugs and inspect the electrodes and ceramic insulator.
Burned or worn electrodes may be caused by these conditions:
- Advanced ignition timing
- Loose spark plug
- Plug heat range too hot
- Insufficient cooling
Fouled plugs may be caused by these conditions:
- Retarded ignition timing
- Oil in combustion chamber
- Incorrect spark plug gap
- Plug heat range too cold
- Excessive idling/low speed running
- Clogged air cleaner element
- Deteriorated ignition coils

If the spark plug electrode is dirty or contaminated, clean the electrode with a plug cleaner.
NOTE:
Do not use a wire brush or scrape the iridium electrode since this will damage the electrode.
When using a sand blaster spark plug cleaner, do not clean for more than 20 seconds to avoid damaging the electrode.

Do not adjust the gap of iridium tip plugs; replace the spark plug if the gap is out of specification.
Electrode Gap
Standard (New): 1.2−1.3 mm (0.047−0.051 in.)

Replace the plug at the specified interval or when the center electrode is rounded. Use only the listed spark plugs.
Spark Plugs
NGK: IZFR6K13
DENSO: SKJ20DR-M13

Apply a small amount of anti-seize compound to the plug threads, and screw the plugs into the cylinder head, finger-tight. Then torque them to 18 N·m (1.8 kgf·m, 13 lbf·ft).

 

The plug holes for # 2 and 3 cylinders may have "shallow" threads from the factory! Note that deposits on the spark plug threaded portion are covering entire length of it.

 

I just notice you responded to me ( I did not came back to this post for a while, I know it,s been nearly 2 years now). Yeah now that you say that, there's a difference (I'll take a look closer, I still have those plug in my stuff, since there were not completely burn off, I kept them as backup just in case). So, does this mean that my engine might have so damage from the factory?