Hrmm...Let's discuss Spark Plugs+Gaps+wires?
 

i did a search with the exact words "spark plug gaps"

and what i've found from searching through random threads is that people say it's good to run .35mm IF your car doesn't backfire....and .28 if it does

any insight on preferences on plugs/wires/gap setups? and it'd be great if someone could provide links as an explanation how plugs work and etc. :) i'm always willing to learn

(in case SOME of you were wondering.... dude who told me he'd show up kinda flaked on me *sigh* so i guess i'm stuck with the car for a while....the girlfriend is half happy and half dissapointed at hte same time....happy i wont be getting a bike and sad that i'm gonna be driving something that could kill me in the rain hahaha)

Are you turbo'd?

If so:
a smaller gap may be necessary to prevent the spark from blowing out in boost. depending on the strength of your coils you may have to run as small as a .025 gap. I am able to run a .034 gap on my squirted 94 at 12-14 lbs of boost without spark blowout. On my other squirted 94 with coil-on-plugs I am able to run a .040 gap at 14psi. See link in sig for COP how-to.

As far as spark plug wires. You really can't beat the factory NGK Blues. Depending on where you buy they are $35-50 and are great.

Factory gap is .040-.043.

The .35mm you speak of is more likely .035", first of all. ;)

Basically, increasing the gap improves driveability (sp?) and idle smoothness a negligible amount, but will probably "blow out" in boost. Narrow the gap until you stop getting blowout under your max boost. I ran .025" with the factory ignition at 14 psi, and run .040" with COPs.

edit: paul beat me!

COPs FTMFW!!!!!!!!!!!!!!

I ran the stock ignition on my 99 with the 100 shot nitrous. I had spark blowout like crazy above 5500. It was like hitting a wall. Power would rise to about 5500 and then fall like crazy. By 6000 it had lost like 100 HP. New wires and plugs didn't fix it. 2 step colder plugs didn't fix it. Hmm, new coil, wires, plugs, and it runs fine without nitrous. Pulls to 7800 (I increased the factory rev limit a bit) but hit a wall on the nitrous. So I dropped the gap from .040 to .030. Helped a lot, but was still not right above 7K. Nitrous motors don't loose top end like that. So I dropped gap to .020. Then it pulled like crazy to 7500 and never skipped a beat. Forever I ran .020 with NO NOTICEABLE DIFFERENCE in idle quality, driveablility, power, etc when not spraying. Seriously. Motor ran fine on .020 gap, plugs stayed clean, motor was as stong and smooth as it was on .040 but on spray the spark was no longer "blown out" as is said.

So after putting 30K on this nitrous motor my experience says plug gap doesn't make a god damn difference. I'd love to see some proof as to why one needs more gap. I mean, it sparks, a flame front propagates, combustion begins, and gases expand and push the pistons. So why does it matter if we use a .020 or .040 spark? I mean has ANYONE ever dyno'd a car at .020 and then some other gap greater than that and concluded more gap=more hp? If there are supposedly "gains", are these gains great enough to clearly show up on a dyno? I've never seen them. Has anyone?

Besides, if you have badass coils and run high gap but have ANY UNDETECTABLE MISS-FIRE in the upper RPMs it will quickly wipe out any gains you 'may' see running more gap. I mean seriously, is it worth it? Risk a lot of power to gain a fraction of a HP maybe?

Also, if you do have a slight undetectable miss-fire with your high gap at say 6800 and up, every miss dumps a cylinder full of oxygen into your exhaust system and your wide band picks that up. It thinks the motor's running lean from the miss. This makes tuning very difficult obviously.

As we all know, the power it takes to make a spark increases by the square of the distance. So when you guys run .040 vs. .020 your asking 4 times as much out of your coils. More heat and energy. And to think people burn up igniters....

That said I'm running EDIS4 now with .020 gap on stock NGK plugs and custom MSD wires. Made a pull today in second gear to 7500 today and it's strong as ever.

Don't get so wound up man, I said "negligible". Being the grammar nazi, you understand that negligible means not discernible. ;)

Furthermore, if anyone running COPs wants to do themselves a HUGE favor, they need to ditch the wasted spark setup for sequential ignition. This would help a ton in comparison to running more gap. Cut the number of sparks in half, you eliminate about half the heat induced into the coils. That's worth doing IMO. Doubles plug life too, though that's not as important to most performance enthusiast.

I hear you. I wasn't really directing that at you. I just don't understand why everyone thinks they need COPs. Kinda like the dual feed fuel rail thing. Everyone speculates, but nobody has real proof that it's better, or for that matter, that there's a problem in the first place. :) Hell, dual feed could be worse! Who knows?! No real conclusive data to say either way. Yet people stand in line to "upgrade" to dual feed. Monkey see, monkey do. (I know there's a term for this. I learned it in Speech but can't remember it)

I've seen Abe's thread so don't link me

Dual feed is another thread, but I do know I couldn't boost past 14 psi at a .025" gap without blowing out the spark. Now I can boost 14 psi with a .040" gap, if I want to turn the boost up, I can, and if I get blowout I can still close the gap. I did notice a little better throttle response after going to COPs, whether that's due to the gap or the hotter spark is probably debatable.

why go colder plugs? whats the effects of hotter plugs?

reason why i brought up this thread is because i'm baffled at what happened to me last week.... it's a symptom i'm not able to fix for some reason....before i've been able to run 20lbs no problem....then my friend touched the car(didn't do anything involving...but he checked my plugs to make sure i didn't detonate on load) he put the plugs+wires back in... i lost boost, the car would bounce and hesitate at aorund 12-14lbs of boost.... i've always kept a .028 gap on my plugs and he didn't mess with the gap at all.... only thing i could recall is that i tried pouring methanol to clean up one of the plugs.... i was told that my wires were probably going bad and i should replace'em... so i went out to discount auto and bought plugs from there...some cheap lifetime warranty plugs(which i will be returning soon since it's not the culprit at all) and i bought some regular NGK BKR6E i believe?... only difference between this setup and the old one i had was the old one was NGK wires...this one is some off brand from discount auto...like $26, and the plugs this time was the v-power NGK BKR6E-11 vs the old i believe iridium-IX'ed BKR6E's

All else being equal, a "colder" plug will be more prone to fouling, however a "hotter" plug will be more prone to causing autoignition during the compression cycle.

The recommended plug temperature varied over the years. The early cars ('90-'93) were spec'd for a 6-series NGK, whereas the later years were spec'd to run a 5-series, which is one step hotter.

There are three common schools of thought as to what heat range a turbo'd Miata should run. The first is to simply go one step colder than stock, which for a 1.6 would be a 7, and for a 1.8 would be a 6.

The second thought is to just run a 7 series regardless of year (speficially a BKR7E) and be done with it.

The third is that for optimal longevity, you should run the hottest plug you can which does not cause autoignition.

Personally, I decided to do an experiment a while back. I took out my 7 series plugs and installed a set of 8 series irridiums. I've been checking them periodically, and have not observed any problems with them. Being something of a paranoid individual, I decided the extra margin of safety was worth it.

Those discount auto wires are absolute garbage Goku, I'd get rid of those ASAP.

Advance sells Bosch Professional Series spark plug wires. When I bought my 99' it had the ORIGINAL spark plug wires on it. I quickly swapped them out for the Bosch wires. They're high quality and were like 40 bucks at Advance and they had em' in stock.

Funny story: Friend had a Jaguar XJS V12. Well it had a gas leak and the top of the motor caught fire one day. Well the fire damaged the old wires so they replaced them with "Omni Spark" brand wires. They were so cheap, I think they were Imported TO China. Anyways car ran like shit. We waited till dark, popped the hood, fired it up, and behold... They don't call em' Omni spark for nothing. The wires were sparking to ground everywhere.

thanks for the up koto....returning them first thing monday/tuesday hahahaha :giggle: i think i'll wait for my NGK blue wires then

quick question for future reference..... how can you tell your car is getting spark blow out? i'm not getting a backfire at all

it feels like the power cuts out under boost.

Missfires coupled with a loss of power.

Were the 7s standard copper? Wondering if the iridium is the difference...

under boost load u mean? because the car gets up to 10-12lbs and then i feel power cuts out really badly..... but no physically heard noises..... the rpm just bounces and when i let off the throttle and the boost gets down to 8-10lbs it runs fine :vash: it's getting irritating because i swapped wires from discount auto(even though i know they're crap...already returned, a waste of 25$ hahaha) and same symptoms, swapped in my NGK blue's back...same symptoms.... i'm gonna order new NGK blue's but i'm unsure if this will help or not...dont want to buy plug wires for no reason

misfire? or backfire? can you elaborate on the events that happen? because mine's silent....no popping noise or anything but i lose power

Gap new plugs to .020. Fixed. Then tell us how it didn't affect idle, cruise, mpg, or anything else.

lol... i guess i'll try the .020?...i hope you were joking about idle cruise mpg and everything else.... hahaha

i had the same problem after i moved from GA to CA every time i would pull hard to 7k i would start to lose power and sputter around 6k till 7k so i checked my #7ngk plug and the cap was at 35 i changed it to 29 and that fixed the problem car runs great all the time. i thought about the COP option but the most i ever boost now is 15psi i think ill get a oil cooler first.

I'm curious to hear back from the guy patsmx5 suggested to regap to .020..

I'm THINKING I;m experiencing blowout. Also no backfire, dont think I'm seeing misfire (at least cant notice) either.

What I AM experiencing is when I pull the car hard, I sometimes get a sudden loss of power/RPM. It doesn't happen everytime, and only when really getting on it.
Perfect example, get on the car up to 6k rpm, then all of a sudden RPM's drop to 5kRPM, and then car comes back to life.
Been wanting to check the gaps, just haven't gotten around to it...

So you're seeing the tach drop suddenly from 6k to 5k and then come back, yes? Do you believe this to be reflective of reality? Seems to me it'd be difficult for the engine to actually do that in the period of time that I envision you describing.

When I was having trigger problems with my MS, I observed this behavior frequently while under heavy load- the tach would drop down suddenly, accompanied by a momentary loss of power, and then come right back. In my case, this was a pickup problem however, which was causing the ECU to not generate spark signals in the first place- misfire due to spark blowout should not actually produce the sort of tach dropout that I think you are describing.

Yes I believe it to be happening, as I dont know anything else that could show my tach drop 1k rpm, even if my foot stays on the throttle...

Another thing is I can't duplicate the condition on command. Sometimes it happens, sometimes it doesn't. It's not WOT, but def 3/4 throttle...usually in 2nd or 3rd gear...right around 6k rpm.

I dont think I'm hitting any kind of fuel cut, and as I said a fuel cut would be very easy to duplicate.

I have to try and catch one of these in a DL

Tony try to log the event. It's most likely spark blowout- I used to see the same before i went to cops with a .035" gap. Its also possible it's acceleration enrichments, under accel wizard your setup for TPSdot right?

I don't see how spark blowout could cause a tach drop. Assuming he's using the stock tach driver of an early '95, the tach output of the igniter is not a closed-loop thing- it gets pulsed whenever the primary operates, regardless of what's happening on the secondary. If he's driving the tach directly from MS, or by diode-OR'ing the SparkA and SparkB triggers, then it's doubly impossible for a secondary-side fault to cause this problem. He's talking about an observable drop of 1k RPM on the tach that happens almost instantaneously, and the engine simply can't change speed that fast.

This really sounds like a CAS trigger problem to me. If you can log an event, I've got $0.01 that says it'll show as a very massive and rapid spike in RPM.

Try new plugs gapped to .020 and see if it fixes it.

I'm gonna try logging it, just keep the laptop in the car till I finally catch it I guess. Also obviously it won't hurt to check the gaps on the plugs.

I haven't messed with any enrichment stuff, not that far along yet, lol.
Just getting the hang of tuning, DLing, etc.

AND I really need to get on my EzTherm...my CLT temp values (and prob Intake Temps) are way off... On a good run my CLT shows CS140's-HIGH170's...

Regapped plugs, I guess I had them on NA gaps? (.035-.040)

Bought them down to .020-.025

Also gonna do some logging and see if I can repeat the event, though hopefully it was the gaps...I just dont know if they'd be blowing out at only 5-6lbs of boost, even with stock gapping