Sparkplug blowout.....almost
 

My son took his 2009 Fit Sport to Walmart this morning to have the tires rotated/balanced. The guy there mentioned to him that as he pulled it into the garage that he thought he smelled gas. On the way back home (three miles return trip) the check engine light came. My son called me and told me what was going on...since the car was running ok and no gas smell he continued home. Minutes later, when he arrived I checked under the hood and smelled "exhaust", but no gas. However, I could not detect any kind of exhaust leakage, just the smell. Using my code reader there was a trouble code 0303 (I think) which said "number 3 misfire". Since his car has 92K and the plugs are original...and since I recalled some people reporting "blown plugs", we decided to pull them and change them out. Number one plug was tight, number two was tight, number three was half-way out of the plug hole and the coil had significant soot all over it. Number 4 plug was at the point of almost being loose.

I've never had this experience before...there is no excuse for this to happen. We were lucky that we found this before any real damage. We also did a valve clearance check and found that almost all the exhaust valves were slightly on the tight side. Intakes were ok. Hope this helps...don't ignore trouble codes. My son reminded me that a few weeks ago he thought he could smell something under the hood. Fortunately over the last few weeks his driving has been minimal.

Good post; disaster averted!

I checked mine several months ago and found all were tight at 60K Miles. Our Fit was bought used. I didn't remove the plugs, but someone had tightened them all to something in excess of 18 LB/FT. I am pleased, but I hope I can an remove them without damage when the time comes. All-in-all, I'd rather have them too tight then loose.

Spacecoast: There have been more than a few that have had loose #2 & #3 plugs that gives them a sooty or melted coil pack / gasoline smell / eventually the Check-Engine-Light (CEL). Not sure why those plugs come loose (mine is a '11 Sport) but have to believe it is either the metallurgy (expand / contract that loosens them) or the way the threads were cut into the head since each spark plug's threads and other dimensions are identical but just #2, #3, and your #4 come loose in some but not all FITs of that vintage.

I guess the worse-case is that the spark plug is leaking while it is still firing well enough not to trigger the CEL. There are several threads on here with pictures of heavily damaged / heat-melted coil packs. The OEM unit is approx $150 and you already know how working on the backside of the engine is a PITA.

As soon as I saw the #3 coil pack and the soot all over it, I tried to determine how far out the spark plug was. I would estimate that it was 40 to 50% out of the hole. All in all we did a plug change, valve adjustment, throttle body clean, new air filter, air box and intake body clean, new belt, new valve cover gasket, and had to replace two clips on the cowl.

Fukushima on the wheels...
ON the plugs that were loose how did the sealing (crush) washer look compared to the plugs that were tight?

Excellent question and I wish I could tell you. In pulling things apart I did look at them but at the time I was concerned with the threads, possible coil damage, and looking at the color of the plugs. I do recall looking at the washers, but not really doing a decent plug to plug comparison. Thought about this the next morning...but too late for the trash pick-up was that morning and they were gone.

My properly torqued (took apart wipers / air management cowling / etc to exposed back of engine) new spark plugs loosened up in less than 500 miles. I wasn't going to take everything apart again, so I used a dab of Permatex blue threadlocker on each plug. Gas mileage returned to normal, no Check-Engine-Light, etc for last 24,000 miles (problem finally resolved ~40,000 and now have 64,000+ on it).

I'm new to the fits ( getting mine Monday) but if they have aluminum heads that can be the issue as the sparkplugs are steel and the 2 metals heat at a different rate so both expand and contract at different rates which can cause them to loosen due to the vibrations from the running motor.

If you look at the plug position its right between the exhaust valves lot of heat there, this isn't a problem unique to the fit, Toyota's 16V do it, 4 cyl BMW's,, Miata's, pretty much a lot of the small high revving 4 cylinders.. Clean threads and a a degree torque will almost eliminate it... I check mine regularly it only takes 15 minutes on my GD or my BMW..

Well good luck trying to check any of the plugs in only 15 minutes on a Honda Fit, much less all of them.

I'm new to the fits ( getting mine Monday) but if they have aluminum heads that can be the issue as the sparkplugs are steel and the 2 metals heat at a different rate
Funny how in the last 45 years with different machinery with aluminum heads I've never had a spark plug come loose...rather they become more difficult to remove.

True to some, due to over tightening, or just plain lucky. Ive had wheel lugs come loose, spark plugs come lose ( even on V6 and v8 ) when I first got my vehicles... but I usually over tighten a bit just to make sure and yes removal is sometimes a little more effort.

*** Just be careful with aluminum heads not to strip out the threads by over tightening too much.***

Our GD developed a barely audible knock or 'putt' sound only when cold...yep, #3 plug was loose. I guess when everything warmed up, it stopped leaking and so, it was quiet.

I installed those plugs (and tightened them to spec) about a year ago myself.

Loose spark plug #2 and #3, exhaust leak
 

https://cimg7.ibsrv.net/gimg/www.fit...9f5b650a12.jpg
https://cimg7.ibsrv.net/gimg/www.fit...1a3c8d9811.jpg
Hello all, just wanted to share my findings on my 2013 Fit sport with 52k miles. I had been getting a slight exhaust smell in the cabin and suspected a leaking exhaust. Upon further inspection the exhaust was in perfect condition, so it of course took me to the internet. I run my own shop so typically I do not have to take my car to a dealer.
A lot of forums say you need to remove the entire front cowl to get to the spark plugs but I was easily able to reach around to change them out 1 by 1. My # 2 plug was not tight but was not leaking to bad, mildly deformed a seal. However #3 was about 1 turn from being out and the boot and plug were very full of soot and completely black.
I changed all the plugs to the Bosch laser cut iridiums as the NGK plugs were double the price. Re installed the plugs 1 by 1 and it runs perfect. These were original and has never been touched by anyone as I am the original owner. I think the only thing keeping the plug in at the end was the plug boot/coil pack. Thank you for the insight.

Glad you caught it! Hope that it doesn't happen again.

Just finished fixing a friends GE Fit that ejected a plug with the threads. About $350 in machine shop labor to add steel inserts into all four plug holes, valve job, new seals, and resurface. $100 Felpro head gasket kit. Plus a whole lot of our time to remove and reinstall the head. Not a fun job!

A few months after I posted this thread my son and his Fit were involved in an accident. Some kid made a U-turn in front of him on a 45mph four lane road with a middle dedicated turn lane. His Fit impacted the kid's right front fender. The kids car suffered little damage, but the Fit's front left corner fender/hood was crushed. The impact pushed his Fit onto its right side, then, as it was sliding down the road, it rolled onto the top as the right side wheels impacted the street curb. Totaled. Honestly, so glad that car is gone. No injuries. Mechanically the Fit was good, but paint issues and just overall flimsiness (and spark plug issues).

What are you guys using for a spark plug torque value. I have found various numbers starting at 11 up to 18 ft/lb.

The manual for the GD calls for 13 ft/lb for whatever that's worth. Not sure I'd go by the factory specs though since that torque value seems to result in blown plugs.

I went with 18 FT/LB so as to match recommendations from spark plug manufacturers for this size in an aluminum head and 18 FT/LB is also Nissan's spec for the same size plug in my other vehicle.

When I checked my Fit with my torque wrench set at 18, I found that they were tightened to something in excess of that. I just let 'em be, figuring that the previous owner cranked them down good. I guess I'd rather face difficulty getting them out later than having them come out on their own.

Thank You .

I have had this issue with my '09 Fit- Had the exhaust odor coming in the vents and took it to my independent mechanic ( I stay away from the dealers). Turned out I had a crack in one of the welds in the exhaust manifold/pre-cat. After that the odor came back again- this time it was loose spark plugs (#2 & 3). The plugs were replaced at 100K , the manifold at 120K and the plugs tightened at 124K