Mods please dont move this to repairing, I wanted to post it here because the most knowledgable Z owners are always in here-as many of you know I am not FI yet....

I was tracking my car Friday night, when after my 2nd pass my car began to misfire. At first it was barely noticable, as I drove home it become worse. The misfire was coming from the passenger side of the motor cylinders 1/3/5. I pulled the code yesterday and it was a P300 mutiple engine misfire code-no surprise there. Today I pull the plugs, on that side of the motor. Cylinders 1 and 3 were fine. I pull #5 and I find the electrode had arched down eliminating the gap in the plug. Pics below, also notice how much richer cylinder #5 is compared to the others. Sorry for the really crappy pics guys.





What could have caused the plug to do this? Is it possible the piston would have touched the plug? I doubt this, I believe if this had happened I would be experiencing engine knock, or have some sort of rod bearing failure. I have a technosquare ecu with rev limit set to 7100, when I warmed up the tires on the second pass I bounced limiter hard a bunch of times. My car has been getting slower and slower over the past few months. I went from trapping 106/107 consistently to 104's last 3 X out at the track in different kinds of weather. Anybody have any suggestions for me? Should I just put stock plugs back in and call it a day? This situation kinda makes me not want to put on my T-netics kit, if this had happened with the kit boosting that would this have blown the motor due to a lean cylinder?

Sorry for the long post just looking for some future advice/reasons why this happened.

BTW HERE is a quick vid of the run where I bounced my rev limiter pretty bad-end result 13.3 @ 104 My car is getting slower and slower!

 

i would find it hard to believe you kissed the piston. usually this is done from a lean cylinder and overheats the electrode enough to almost melt it. i have melted them before, lol. once those touch the cylinder will no longer fire, or fire intermittantly which could contribute to the rich appearing plug. i would try putting in new plugs, drive easy for a couple hundred miles or so then pull out again and inspect, maybe less. you could have something as simple as a malfuntioning injector or clogged injector on that cylinder. good luck

 

I wish i could help, but like you said i think it is cause of excessive hardcore driving, bouncing of 7100 is really hard on the engine, also the ecu reflash could of thrown of timing. I have heard of cases before like that. Call technosquare and tell them about your problem. Also you can trying getting the greddy spark plugs with your turbonetics kit they will work great, they can stand the constant beating.

 

Nice video

 

you can try a compression test, no?

if everything is good there it's something simple most probably

 

I havent but I guess I could when I change the plugs. Anybody have any input on why my car seems to be running so sluggish lately? It just doesnt pull like it used to, I dont want to put the St kit on until I get it running 100%. Anybody know where the cheapest place to get plugs are? Thanks for the input guys, appreciate it.

 

i'd check the compression on that cylinder, thats not just rich(fuel) on the end of that plug. Bad rings? My guess.

 

My car "only" has 53K NA miles, how could the rings be bad? It has never burned more than 1/2 quart of oil in 3000 miles intervals, it has been a solid motor. Id hate to see that compression is low in that cylinder. Id probobly sell it I dont feel like dealing with something like that, ugghhh

 

Is just the plug bad, or did you burn a coil as well?

 

Isn't cylinder 5 the one that kept blowing the motors when fi 1st came out due to running lean? Also I wouldn't run a raised rev limiter with fi on stock bottom. Change the plugs and see what happens.

 

for plugs...talk to sharif..i just got some from him...

as for the pic there...is that oil on that electrode of the second plug?...any visible oil at all? the pics are blurry and difficult to make out 100%
do a compression test and a leakdown...then based on those findings...if negative for anything major... throw some new plugs in...what's your gap set at?

 

All 3 plugs looked like they had oil on the threads, but they didnt feel like they had oil on them nor did it smell like oil, just looked old and burned out. I never thought that the cylinder #5 could have a clogged injector causing the lean situation, obviously that plug couldnt fire so thats why the plug looked so rich when I pulled it. The gap is stock(im not sure what it is, but I can check them), like I said this is the first time I have taken the plugs out. Does Sharif sell Iridium plugs in stock heat ranges? Id rather buy some plugs that will work with the turbo kit that Ill hopefully be installing over the winter. Thanks for the input guys Ill perform a compression test hopefully tomorrow and Ill let you know. Oh and as far as the coil question I didnt have any other codes other than the one I listed above, if a coil was bad wouldnt it have thrown a code for that? Thanks again

 

I'm sure Sharif's ears are burning about now...I'm sure he'll reply soon to address the heat range question
i run 1 step colder and i'm running 16psi...
my gap is .035 (i believe stock is .045)

plugs should have a whitish color to the electrode and surrounding area...black, wet oil is always a bad sign..unfortunately i know from personal experience...do a compression/and leakdown test

good luck
TODD

 

It wouldn't neccesarily throw a code. When I burned my coil, it just gave me a CEL, didn't give me a code that said I burned a coil... my plug looked just like urs though.

 

Change the plugs, and I am 99% sure you will be fine. Detonation or extreme heat can bend the ground strap...I highly doubt the piston hit the plug, based on where the plug sits in the combustion chamber.

I have the NGK one step colder in stock, which are good for FI cars. If you want the standard heat range, I can order them for you. Iridiums are a lot tougher than the stock plugs. Here is the link: http://www.forgedinternals.com/store...cat=264&page=1

 

your engine was spitting oil out too from under the cap... now that is freakin' weird, to me at least... and you said you had some oil on your plugs too? definately check the compression as soon as you get the new plugs. I really hope your rings are fine, and its just a one time instance due to rev bouncing.

did you take all the plugs out, or just these three? how do the 2-4-6 plugs look?

 

Well....something has happened here to bend the electrode. Being N/A I would think detonation would be HIGHLY unlikely due to the safety features built into the ecu for things like bad gas, etc. And like Sharif said, piston contact is not probable due to piston design and the quench area around the plug. Looking at that electrode it looks like unburned fuel coking on the end of the plug. From the heat of the engine and intermittent spark, excess unburned fuel in that cylinder would give that apperance. Same as if the engine was running extremely rich. If it was oil it would be greasy in appearance and not like this dry black soot. Oil tends to stay on the plug while fuel tends to evaporate. Based on the mileage of the motor I would say it is possible that the initial electrode damage may have been from a thick carbon chunk that may have broken loose fron the top of the piston. I have seen some extremely thick deposits on piston tops before. Like others said earlier, I would change all the plugs and all should be fine.

 

Is that oil or gas where the threads stop on that plug on the left in the second pic?(brown looking)

 

The messed up plug is probably what is causing your car to be "sluggish". That cylinder is probably making nearly no power. Put some new plugs in and I bet it will run perfectly.

Besides...if something is wrong with your motor (which I highly doubt it is)...you're still inside the factory drivetrain warranty.

 

Thanks for the advice guys, Sharif Ill contact you today. Should I also try and run some fuel system cleaner in case an injector may have become clogged?