Coil Dwell Settings with ProTuner & AccessPort
 

OK Brettus started a thread in Ignition Timing that spawned a crap fest on Dwell settings. I was actually starting to get into the whole discussion but it was distracting the original threads intention.

I thought I would start a thread to continue the dwell discussion.

So to start with,

And then

So now we believe/understand that the dwell table shows % of crank rotation time I am curious what people are running with what coil setups.

We have 3 common setups that I am aware of OEM, LS2 (BHR) and Bosch HEC 715 (MazSport). I am curious what people are runnning.

Kane posted some in the Timing thread:


https://www.rx8club.com/attachment.p...1&d=1240679475

https://www.rx8club.com/attachment.p...1&d=1240679475

EDIT: Updated this to a more recent map that is working much better
HEC715
https://www.rx8club.com/attachment.p...1&d=1251463576

I deleted the dwell thread I started because there was too much misleading info in it .
From that thread I learned a few little titbits but still do not understand how the mazda map relates to the actual dwell at the coils .
I did get this gem of info from someone though :

It is so unbelievably simple that a trained monkey could work it out . However no-one apart from MM ever did , so maybe you actually need to be one :dunno:

i love this community.

cool thread. lots of questions.

you're not that far from stock with the HEC. you have a shorter charge time towards the top, right?

what effect does charge time have on performance?

is a longer charge time in the later rpms better?

is a longer charge time tougher on coils?

the bhr coils have a long charge towards the top, right?

can dwell be tuned for performance without changing coils?

That just makes me sing the theme song for a TV show here called "Are you smarter than a 5th Grader" (replace 5th grader with trained monkey).

It has its moments!

yes. BUt that doesn't mean its what works best. In fact its one of the reasons I started this thread was to find out what people were doing with them.

I will start by saying I am the last person to be answering this but my first thoughts are that its like a camera flash, it needs to charge long enough to have sufficient power to light the bulb. If the charge time isn't long enough, the spark may not be strong enough to light the fuel. Not sure what happens if you charge to long.

This is one of the things I am trying to figure out...

Good question, not sure.

In comparison to the OEM ones in NA form yeah. Not sure how they would be configured in FI form. I am making the assumption here that the same coil should be different NA v FI.

No idea about performance but regardless of the coil on the car you can change the dwell settings.

Cheers

Andrew

No one got any feedback on the dwell of the Bosch/Mazsport Coils?

Ooooo good questions!

To establish a basis, my understanding is dwell is the overall charge time where the coil generates a magnetic field. When this field collapses it creates a discharge which is what lights the electrode on the spark plug. Someone stop me if I'm off base.

Different ignition coils have different dwell operational ranges. It mostly depends on the vehicle application. The longer the dwell the larger the charge. There are extremes on both sides.

If a coil isn't given enough dwell time it's not able to form a strong enough magnetic field which results in a weak spark. With this you're looking at incomplete or no combustion at all. On the flip side, there is a point where excessive charging doesn't result in a more powerful field and instead it's turned into heat energy.

Excessive charging will overheat the coils and shorten their life. Also you only have so much crank rotation time before you have to fire off the spark plug.

Longer dwell times only become an issue in the upper RPM band because as the motor spins faster you have less time to charge the coil.

Spark discharge needs to be its strongest at the torque peak because this is where combustion chamber pressures will be at their highest.

Dwell can be adjusted without changing the coils, however it will depend on the design of the coils in question as to what dwell settings are effective.

The coil properties should not be any different from NA to FI - they should be what the coil wants / needs to make maximum energy without burning out.

Having said that - I have confirmed the dwell test in the TSM - and OD got me this info... so it looks like I am right for wrong reasons maybe... but I really don't care about the why - only that it works.

And again BHR needs 5ms of dwell.

This jives with the Service Manual testing procedures. 3.3/5 or 3.7/5 = 135 to 150% increase in dwell..... I don't know why this is so mysterious.

Kane, when I did my dwell map i noticed that on yours you decresed the dwell at 1,000 rpms from the stock dwell time??

I don't think so.... I may have made a mistake.... Hmm.

Looked it up and you are right.... I wonder how that happened.

Can someone please show me how to adjust the BHR coils to 5ms of dwell using AP? I'm not much of a tuning guy.

/\ that my freind is what all the fuss is about ....

You guys are fuckin killing me....

It looks like this has been solved, then? Yes?


I take it there is no longer need to dwell on this issue? Wow, that never gets old.

Good one.

is there any concern on longevity with increasing dwell 135-150%?

in the first post, how come the bhr coil values are not 135-150% of the oem dwell?
Where are these values from?

On stock coils? I have been told, yes. You will burn them out and there is no reason to do it anyway.

On Yukons? Again, this is the core of the whole issue, but Yukons are fine out to 8ms, I think, where they have an internal quench or cutoff.

does not look solved to me but i've always been a "gotta know how stuff works" kinda guy .
Did MM threaten to burn down your house if you divulged anything ?

You guys crack me up.

Take a step back and look at what you are trying to do.

It is genuinely so simple, its sickening.

yup, so easy that I updated my dwell settings yesterday.

Interesting. what does 5ms mean? Sorry I just don't know even half the stuff about coils that other people do.

lol!

You cheated!

if you're not cheating, you're not trying hard enough.

lol. You give me too much credit. I know just about as much as you do. The only thing that I know more than you is that I know that all I know is no more than you know. :SHOCKED:

Like I said. Once I can confirm what I learned from MM, I will be happy to share. Stick it to the man, so to speak. Until then, all I could say would be hearsay.

Besides, the whole drama is entertaining. Like "Days of our Lives" 20 years later I fully expect Bo and Hope to be almost getting married. And Sammy or Stephano trying to kill everyone.