Judging by that dwell curve for the '00 i should be running more like 5.2-5.3 on my '99. That is a pretty long dwell and I was under the impression that the NB coils weren't very robust for that kind of current.
So that would be great if I could safely run a dwell of 5.2 and not fry my coils.

Hmm... I must have missed where the 1.6L and 1.8L NA coils are posted. Tried a search, but couldn't find it. I just wanted to be sure as I have conflicting information. The AEM tells me dwell times are in the 1.7ms range, other post have said they are running 5ms for the 1.6L.

I'm suspecting that AEM probably didn't test the coils to come up with optimal values. They may have just taken the stock mazda ecu and put it on the bench to measure what the dwell outputs are. If I can maximize the dwell settings and get a better spark, I might not need to change anything on my car to cure the misfire.

I am running 5ms @ 12v on my MS/1.6. That is the value Jerry @ DIY Autotune scoped out from the stock computer.

With these much shorter dwell times--2.5ms for the toyo coils vs 5.0ms for the mazda coils--does this mean that under higher load it is possible for a hotter spark, as the coil had enough time to completely charge. Let me put it another way, with a dwell of 5.0ms and wasted spark, is it possible that spark events could be called upon before the mazda coil had the required 5.0ms to charge fully?

Wow, if the stock ECU actually has a dwell period of 5ms, with these toyota coils, wouldn't they be overheating? Your charging them twice as long.

You didn't say NA 1.8 :)

I would think there would be a good chance of overheat. Luckily most of us run MS, AEM, or Hydra so not a problem.

Ive put 300 miles on mine on the stock ecu so far. longest trip has been 150miles, I've had 0 problems.

More data. I will type it here for posterity. If I keep it in a notebook I will more likely lose it.

Toyota coils
------------
primary L: 4.7mH below 5.2A, 1.6 mH above
current limit: 10A
delay from signal to beginning of output voltage rise: 6 uS
rise time to 20 kV: 12 uS
peak voltage: 37kV
rise time to 37kV: 48uS


2001 coils:
-----------
primary L: 7mH
current limit: 6.5A
delay: 6uS
rise time to 20 kV: 25 uS
peak V: 25kV
rise time to 25 kV: 65 uS

'00 coils:
--------
primary L: 10 mH
current limit: 6A
delay: 8 uS
rise time to 20 kV: 13 uS
peak V: 36kV
rise time to 36kV: 38 uS

TEC3 coils:
----------
primary L: 3mH
current limit: 5A engine idling with the TEC running
rise time to 20 kV: 9uS
rise time to peak of output: 30 uS
peak output at 4A of current is 35kV
peak output at 5A of current is 40 kV (limit of the high voltage probe)


The TEC coils appear to have a very high output voltage indeed. It seems to have a high turns ratio, and low capacitance. This would also translate to a lower current spark but long duration (with a high peak voltage capability of igniting hard-to-ignite mixtures)

TThe '00 coils are good.

The Toyota coils are good but don't have the same energy storage as the '00 coils.

The '01 seems lousy in comparison, in terms of peak voltage capability and delay. At 7200 RPM, there are 23 uS per degree of timing. If this translates to any real-world performance loss, I don't know.

What is the deal with 97 coils?

Lazzer408,

FYI, I just logged the dwell time on my AEM for the 1.6L default settings. The dwell time is 3.5ms, but it starts to go down at about 4400 rpm. I believe this is because the max dwell is set at 0.5 teeth. So it progressively decreases with the RPM. I'm not so sure why AEM set it like this. Actually I'm not so sure why they would have a max dwell time dependent on the crank angle. It might be the reason why I was getting misfires on the higher rpm boost ranges.

Just to make sure that i've got this all right before i change my settings.
Would a dwell of 4.25ms for 12v be ok to use for my dwell with my '99 coils or is it going to cooke them?

If I understand correctly, these Toyo coils have a smart dwell function that will force a discharge if dwell time is too long, preventing them from cooking due to too long dwell.

If that is the case, should I still use a fixed dwell setting, or should I allow the COP to set its own dwell?

Thats a good question. I originally had 4 COPs that were slightly longer than the ones everyone was using that were running on the stock ecu for about 2 weeks before I started building the ms2 a while back. Well I somehow burn one out testing that out so I ordered another set. These ended up being the shorter ones everyone is using right now.

Here is were the story gets interesting. I only replaced the one COP that burnt out with one of the new ones I had gotten. The stock ecu ran everything great. By this time I had decided on MSI instead of II and had already built what should be a working version. The problem was that I couldn't get it firing on a cylinders. Well I had had enough after messing with it for 2 weeks and just threw the stocker back on. That weekend I went home and hung out with brad and scott while they "installed" his torsen while I messed with MS some more in the driveway. I eventually found out that the old COP fired on inverted and the new ones on normal. Very strange indeed that I was able to run the car perfectly on the stock ecu with that mix without ever killing a single one.

So, I'm not really sure how I was able to kill one with the msII but I was able to run them mixed with 3 of the originals surely charging the entire time they should be off.

No, it doesn't "force a discharge", it current limits, and will still fire normally.
HOWEVER, during current limiting, the ignitor will get hot, and will burn out if you do it all the time.

If it "forced a discharge" it would cause the spark to occur way too early with a possible bent rod.

Thanks Jason. That's very good information, and exactly what I need to know. I've set my MS for 2.5ms@12V. Unfortunately, I can't control the rate of dwell change with voltage change, so it is some what of a WAG as to what's happening at running voltage of 14V

Ben, MS assumes 12v and make corrections: at higher voltages the time is reduced; lower, increased.

of course. but how much correction? we know it changes, but we don't know the rate of change.

look it up in the code? I'll take a gander myself.

Good lord, jason, you rock. Sweet curve. If I were still using stock coils, I would totally care. You don't have those for the toyota COPs, do you? :-)

edit: Sorry, totally missed the FIRST post. Abe McDouche, reporting for duty.