Spark plug #4, For Art Options

[lagos]

ive been dealing with some odd lean issues on my car the past few weeks. having a wideband in the car, really opens up your eyes. so far, i found 2 things that were affecting my a/f ratio. 1st one was that i had a fuse tap running from the ignition fuse to power my gauges and other car electronics. i added the wide band to that, and out of nowhere i started getting detonation at almost any boost level above 10psi. turns out, that your ignition fuse is what powers your injectors, fuel pump, etc.. and this was causing some type of current draw, and not giving the power the injectors needed. moved the fuse tap over to the cig lighter fuse, and that problem went away.

the other thing i found, is that i had a TINY air leak in my intake piping. i didn't even know it untill i noticed it while boost leak testing through the intake. after fixing it my a/f ratio got more rich. so you might want to look into those 2 things.

here is a pic of my plugs. its kind of old. from 5.26.06. you can see too much heat on them. this is mostly from the advanced timing in the jdm ecu's. you can also see cylinder 3 looking a lot leaner then the rest of them .




now these next ones are from a few weeks ago, after fixing some things. you can tell they look a lot better then the 1st set. you can clearly see how plug 1 and 4 are more rich then 2 and 3. this is what im hoping to find out if the ats rail fixes. if it does, i would buy one.



This post has been edited by lagos: Oct 8, 2006 - 11:48 PM

[Bitter]

lagos, other than being lean and doing a bit of cold driving, your plugs look better than mine and i'm not boosted at all! i see a little detonation on mine, but theyre the same plugs i had at 20degrees.

there should be a thread all about plug reading with examples of each condition it really is a useful thing to know and can tell you soooo much about whats going on.

[x_itchy_b_x]

just pulled them when i got out of work. i also have a JDM ecu but i dont seem to have that problem.
the outer threaded ring shows its ruch at idle and the porcelain shows it fine under WOT, look good to me.
but I should really being running a colder plug for the higher boost, ill be going with NGK bkre7's or w/e... somthing like that. those are stock Denso plugs i picked up from the dealer.

This post has been edited by x_itchy_b_x: Oct 9, 2006 - 5:17 PM

[lagos]

those look really good.

[hurley97]

Nice pink blanket you got there Art

[Silver94CelicaOw...]

Those plugs do look very good, John.

I remember a magazine I read a while back had a great article on reading plugs, setting gap, and what temp plugs to use for what sort of applications. Pretty good article.


I know its not a FI motor, but after changing spark plugs on my 5SFE you could see the white on the old ones indicating either a hot/lean motor condition. I put fresh new plugs in, and the condition looks identical.
I'm quite confident that this is due to me driving 60+ miles on the highway every day last year at about 80 MPH....at those engine speeds (~4,000 RPMS) and not delivering much fuel due to a low throttle position, my best instincts told me that this causes a plug to appear relatively lean even though I'm sure the factory tune is A-OK on the motor.

Unless the injectors or fuel filter are pretty clogged or theres a vacuum leak that causes a lean off-throttle condition to the fuel system, I would think that my plugs aren't a great indicator of my engine condition, no?

Jeff, maybe your vacuum leak could be causing the "lean plug" appearance both at idle and at while cruising on the highway at high RPMS where fuel consumption depends more on the vacuum present at the fuel rail??

[lagos]

Nice pink blanket you got there Art

its a red shop rag

[Bitter]

it turns blue if it gets acid on it

[lagos]

Those plugs do look very good, John.

I remember a magazine I read a while back had a great article on reading plugs, setting gap, and what temp plugs to use for what sort of applications. Pretty good article.


I know its not a FI motor, but after changing spark plugs on my 5SFE you could see the white on the old ones indicating either a hot/lean motor condition. I put fresh new plugs in, and the condition looks identical.
I'm quite confident that this is due to me driving 60+ miles on the highway every day last year at about 80 MPH....at those engine speeds (~4,000 RPMS) and not delivering much fuel due to a low throttle position, my best instincts told me that this causes a plug to appear relatively lean even though I'm sure the factory tune is A-OK on the motor.

Unless the injectors or fuel filter are pretty clogged or theres a vacuum leak that causes a lean off-throttle condition to the fuel system, I would think that my plugs aren't a great indicator of my engine condition, no?

Jeff, maybe your vacuum leak could be causing the "lean plug" appearance both at idle and at while cruising on the highway at high RPMS where fuel consumption depends more on the vacuum present at the fuel rail??

reading plugs IS very tricky because certain parts of the plug tell you different things. so maybe the white you saw, was just fine. it could also just be a problem with the brand of plug or heat range that you used.

when you are cruising on the highway, you are at 14.7 afr (aka stoich). when u lift off the throttle, the car goes VERY lean. this is totally normal, and shouldn't show up on the plugs.

here are some good sites for plug reading

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

http://www.maxracesoftware.com/spark_plugs.htm

This post has been edited by lagos: Oct 9, 2006 - 10:29 PM

[x_itchy_b_x]

i guess "reading" plugs is just old technology, i think ill trust a wideband
also those plugs i showed have seen 20+ psi... so im not sure what that might do to them lol.

This post has been edited by x_itchy_b_x: Oct 9, 2006 - 10:37 PM

[Bitter]

wideband is useful, but theres alot to be gleened from reading the plugs.

[Defgeph]

My fuel rail o ring was torn on # 4. This might be causing that light color.

[x_itchy_b_x]

what brand gas do you use? maybe thats just how it burns?
I use shell the cleaning one, forgot the name.

[Defgeph]

what brand gas do you use? maybe thats just how it burns?
I use shell the cleaning one, forgot the name.

I have been using race gas. Sonoco 100 & 110 octanes.

[x_itchy_b_x]

hmm. i mean plugs normally dont lie, but in your case if u run 100 and 110 octane there is no way you are knocking or detenating, esp on 15-17psi. hows your timing? did your distro turn? i dont see how you have that white, hot look to them. i think all a bad o ring would do is seat poorly and risk leaking other than that it shouldnt affect any of this since its outside the combustion chamber. is that fuel leaded or somthing?

[Bitter]

a bad oring could have been leaking air and leaning that one cylinder enough to knock. the leaner the mix the more prone to detonation it is, even if its high octane. octane is knock resistant to compression, not knock resistant to heat or a lean mixture. its a different situation. you dont run race gas any leaner than you do 87 octane, its still all gasoline and its stoicheometry is the same regardless of octane. too much air and it will burn too hot and do bad things.

[x_itchy_b_x]

a bad oring could have been leaking air and leaning that one cylinder enough to knock. the leaner the mix the more prone to detonation it is, even if its high octane. octane is knock resistant to compression, not knock resistant to heat or a lean mixture. its a different situation. you dont run race gas any leaner than you do 87 octane, its still all gasoline and its stoicheometry is the same regardless of octane. too much air and it will burn too hot and do bad things.

i highly doubt air will leak in a cyclinder when its forced induction if anything it will blow air out.
i guess we need a pic of all 4 to see if that o ring is whats doing it.

This post has been edited by x_itchy_b_x: Oct 10, 2006 - 12:25 PM

[Bitter]

what about when you're off boost and timing is advanced more?

[lagos]

his plug looks just like mine used to. the grounding strap shows a little too much heat (but not as bad as mine are in my 1st pic). the a/f ratio looks ok, but you do see sings of detonation. after dealing with detonation on my car, ill tell you that the 3s is very picky about how things are done, once you go past the stock 10psi. you cant just blindly turn up the boost to 15psi, just because mr2oc says so.

i think jeff has had these plugs in there for a while, and has often run 15 and even 17psi. since they are stock heat range, thats the first thing i would change.

after that, i would highly recommend everyone install the tvsv led's to monitor their knock response, if they plan to run anymore then stock boost. its a great way to know, if a random spike of boost, caused knock or not or of your car is happy with you while you are doing that 1/4 mile run.

[x_itchy_b_x]

but then my plugs should look the same since they are stock denso's and have never seen anything lower than 15psi. and upwards to 20+ a few times.
its all about good intercooling, wich jeff def has with hi W/a and the RC tune.

This post has been edited by x_itchy_b_x: Oct 10, 2006 - 1:44 PM