optimizing the ignition system w/ megasquirt
 

I am wondering what plugs, gaps, and dwell settings are everyone using on their 1.6 megasquirt setups? I personally run the NGK extended reach plugs from FM at whatever gap they set them to (I asked and they said they were pregapped). Also got NGK blue wires. My running dwell is 4.5 with a .5ms minimum discharge time. I use those settings because I know they work, but has anyone run anything different? I know the pnp settings are using 3.5 running dwell so i might be going a bit high.

The FM plugs fucking suck. Get rid of them for either stock plugs or one step colder. I lost response, power and mileage when I put them in. Got it back when I pulled them out. I'm running stock plugs right now at .035 or something.

I have NGK blues on the car now, but I usually run Magnecore reds. Dwell is 5.0 ms.

ok, and you are specifically referring to the NGK extended reach 1 step colder plugs? If so thats the first time I have ever heard of this ... so what brand plugs? .035 sounds like a good gap, i think the FM ones are .03

On the early MSPNP MM9093 maps we ran 3.5ms dwell, I've more recently done some testing with the scope and found that 5ms is more on target with what the stock ECU was commanding. I've been running 5ms on our car, and Ben has on his, for over a month now.



Bear in mind these variables...

If you've substituted different coils, dwell needs will change.

If you're not running an MSPNP, but you are running DIYAutoTune's mods to the letter, these settings should be fine. If you are running different hardware mods, `it would need to be tested.


My recommendation on plugs would be NGKs, 1 or 2 steps colder than stock (start with 2, if they foul go to 1 step colder than stock, but I bet 2 steps colder is just right) and gap them narrower than stock, I think .035 is stock right? I'd gap them at .026-.028. I've seen, firsthand, on the dyno, this cure spark blowout issues under boost. This was on Miatas.

Yes I am specifically referring to the NKG ER plugs that FM recommends. They SUCK.

They are assuredly uber safe to run, even on a track car. I'm sure that's why the recommend them (that and they're hard to find locally which makes you want to order from them for 3x retail).

With my last intercooler, I detonated after a few WOT runs and stock plugs. I replaced them with the FM plugs, and the detonation went away, but I had the problems listed earlier. When I put the new intercooler in, I put oem ngk's back in and it was night and day better.

If I were going to track I'd put in one step colder. For the street, the stock plugs are good for me.

I put the NKG ER plug in my lawnmower, and have 3 spares. :greddy2:

lol funny shit. After some reading up on msefi.com I have a better understanding of what is going on. The coil takes a certain ammount of time to charge (dwell) and if i set the ammount too high then i can overheat the ignitor/coil. Minimum discharge time is how long it takes for that energy to be dissipated in the form of a spark. I think im going to mess around with that setting now that I know it wont blow my shit up, or maybe it will

you don't want to mess with the spark settings. there's no reason to.

if you increase dwell time there's a fair chance of killing the ignitor. if you lower dwell time, you rob yourself of power.

just "cop" a feel. everyone's doing it!

well I ran around town with a .02 ms minimum discharge and 4ms dwell time and it seemed to be just fine, no real difference that I can tell. No spark blowout under boost.

same setup as you, only with regular NGKs one step colder. runs good.

awesome, im definitely going to be gettin some new spark plugs here soon. Now I wonder why the extended reach act differently? I suppose if it worked so much better OEMs would have figured it out long ago and use that. Im going to miata.net to see if theres any discussions about em.

1) 1000ms per second, 60 seconds per minute .... 1000 x 60 = 60,000 ms per minute
2) 60,000ms (1min) / 7000 (rpm) = 8.57ms per engine revolution
3) Since our engine is a four stroke with a wasted spark setup, each coil fires once each revolution
4) Therefore the coil has 8.57ms to get ready for each upcoming spark. If I run 5ms dwell time + .5ms discharge, I am only using 5.5ms of this time.

just threw my thoughts out there.

I dont use the MS but I run the NGK BKR7E plugs at .032. ATV stores have it since it fits the Polaris Sportsman quads. I couldn't find this plug at any of the auto parts stores so I hit up the motorcycles shops and found them for $2.39

:bigtu: